Index: head/UPDATING =================================================================== --- head/UPDATING (revision 294494) +++ head/UPDATING (revision 294495) @@ -1,1489 +1,1485 @@ Updating Information for FreeBSD current users. This file is maintained and copyrighted by M. Warner Losh . See end of file for further details. For commonly done items, please see the COMMON ITEMS: section later in the file. These instructions assume that you basically know what you are doing. If not, then please consult the FreeBSD handbook: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html Items affecting the ports and packages system can be found in /usr/ports/UPDATING. Please read that file before running portupgrade. NOTE: FreeBSD has switched from gcc to clang. If you have trouble bootstrapping from older versions of FreeBSD, try WITHOUT_CLANG and WITH_GCC to bootstrap to the tip of head, and then rebuild without this option. The bootstrap process from older version of current across the gcc/clang cutover is a bit fragile. NOTE TO PEOPLE WHO THINK THAT FreeBSD 11.x IS SLOW: FreeBSD 11.x has many debugging features turned on, in both the kernel and userland. These features attempt to detect incorrect use of system primitives, and encourage loud failure through extra sanity checking and fail stop semantics. They also substantially impact system performance. If you want to do performance measurement, benchmarking, and optimization, you'll want to turn them off. This includes various WITNESS- related kernel options, INVARIANTS, malloc debugging flags in userland, and various verbose features in the kernel. Many developers choose to disable these features on build machines to maximize performance. (To completely disable malloc debugging, define MALLOC_PRODUCTION in /etc/make.conf, or to merely disable the most expensive debugging functionality run "ln -s 'abort:false,junk:false' /etc/malloc.conf".) 20160119: - The default configuration of ssh(1) no longer allows to use ssh-dss - keys. To enable using them, add 'ssh-dss' to PubkeyAcceptedKeyTypes - option in the /etc/ssh/ssh_config. Refer to ssh_config(5) for more - information. The NONE and HPN patches has been removed from OpenSSH. They are still available in the security/openssh-portable port. 20160113: With the addition of ypldap(8), a new _ypldap user is now required during installworld. "mergemaster -p" can be used to add the user prior to installworld, as documented in the handbook. 20151216: The tftp loader (pxeboot) now uses the option root-path directive. As a consequence it no longer looks for a pxeboot.4th file on the tftp server. Instead it uses the regular /boot infrastructure as with the other loaders. 20151211: The code to start recording plug and play data into the modules has been committed. While the old tools will properly build a new kernel, a number of warnings about "unknown metadata record 4" will be produced for an older kldxref. To avoid such warnings, make sure to rebuild the kernel toolchain (or world). Make sure that you have r292078 or later when trying to build 292077 or later before rebuilding. 20151207: Debug data files are now built by default with 'make buildworld' and installed with 'make installworld'. This facilitates debugging but requires more disk space both during the build and for the installed world. Debug files may be disabled by setting WITHOUT_DEBUG_FILES=yes in src.conf(5). 20151130: r291527 changed the internal interface between the nfsd.ko and nfscommon.ko modules. As such, they must both be upgraded to-gether. __FreeBSD_version has been bumped because of this. 20151108: Add support for unicode collation strings leads to a change of order of files listed by ls(1) for example. To get back to the old behaviour, set LC_COLLATE environment variable to "C". Databases administrators will need to reindex their databases given collation results will be different. Due to a bug in install(1) it is recommended to remove the ancient locales before running make installworld. rm -rf /usr/share/locale/* 20151030: The OpenSSL has been upgraded to 1.0.2d. Any binaries requiring libcrypto.so.7 or libssl.so.7 must be recompiled. 20151020: Qlogic 24xx/25xx firmware images were updated from 5.5.0 to 7.3.0. Kernel modules isp_2400_multi and isp_2500_multi were removed and should be replaced with isp_2400 and isp_2500 modules respectively. 20151017: The build previously allowed using 'make -n' to not recurse into sub-directories while showing what commands would be executed, and 'make -n -n' to recursively show commands. Now 'make -n' will recurse and 'make -N' will not. 20151012: If you specify SENDMAIL_MC or SENDMAIL_CF in make.conf, mergemaster and etcupdate will now use this file. A custom sendmail.cf is now updated via this mechanism rather than via installworld. If you had excluded sendmail.cf in mergemaster.rc or etcupdate.conf, you may want to remove the exclusion or change it to "always install". /etc/mail/sendmail.cf is now managed the same way regardless of whether SENDMAIL_MC/SENDMAIL_CF is used. If you are not using SENDMAIL_MC/SENDMAIL_CF there should be no change in behavior. 20151011: Compatibility shims for legacy ATA device names have been removed. It includes ATA_STATIC_ID kernel option, kern.cam.ada.legacy_aliases and kern.geom.raid.legacy_aliases loader tunables, kern.devalias.* environment variables, /dev/ad* and /dev/ar* symbolic links. 20151006: Clang, llvm, lldb, compiler-rt and libc++ have been upgraded to 3.7.0. Please see the 20141231 entry below for information about prerequisites and upgrading, if you are not already using clang 3.5.0 or higher. 20150924: Kernel debug files have been moved to /usr/lib/debug/boot/kernel/, and renamed from .symbols to .debug. This reduces the size requirements on the boot partition or file system and provides consistency with userland debug files. When using the supported kernel installation method the /usr/lib/debug/boot/kernel directory will be renamed (to kernel.old) as is done with /boot/kernel. Developers wishing to maintain the historical behavior of installing debug files in /boot/kernel/ can set KERN_DEBUGDIR="" in src.conf(5). 20150827: The wireless drivers had undergone changes that remove the 'parent interface' from the ifconfig -l output. The rc.d network scripts used to check presence of a parent interface in the list, so old scripts would fail to start wireless networking. Thus, etcupdate(3) or mergemaster(8) run is required after kernel update, to update your rc.d scripts in /etc. 20150827: pf no longer supports 'scrub fragment crop' or 'scrub fragment drop-ovl' These configurations are now automatically interpreted as 'scrub fragment reassemble'. 20150817: Kernel-loadable modules for the random(4) device are back. To use them, the kernel must have device random options RANDOM_LOADABLE kldload(8) can then be used to load random_fortuna.ko or random_yarrow.ko. Please note that due to the indirect function calls that the loadable modules need to provide, the build-in variants will be slightly more efficient. The random(4) kernel option RANDOM_DUMMY has been retired due to unpopularity. It was not all that useful anyway. 20150813: The WITHOUT_ELFTOOLCHAIN_TOOLS src.conf(5) knob has been retired. Control over building the ELF Tool Chain tools is now provided by the WITHOUT_TOOLCHAIN knob. 20150810: The polarity of Pulse Per Second (PPS) capture events with the uart(4) driver has been corrected. Prior to this change the PPS "assert" event corresponded to the trailing edge of a positive PPS pulse and the "clear" event was the leading edge of the next pulse. As the width of a PPS pulse in a typical GPS receiver is on the order of 1 millisecond, most users will not notice any significant difference with this change. Anyone who has compensated for the historical polarity reversal by configuring a negative offset equal to the pulse width will need to remove that workaround. 20150809: The default group assigned to /dev/dri entries has been changed from 'wheel' to 'video' with the id of '44'. If you want to have access to the dri devices please add yourself to the video group with: # pw groupmod video -m $USER 20150806: The menu.rc and loader.rc files will now be replaced during upgrades. Please migrate local changes to menu.rc.local and loader.rc.local instead. 20150805: GNU Binutils versions of addr2line, c++filt, nm, readelf, size, strings and strip have been removed. The src.conf(5) knob WITHOUT_ELFTOOLCHAIN_TOOLS no longer provides the binutils tools. 20150728: As ZFS requires more kernel stack pages than is the default on some architectures e.g. i386, it now warns if KSTACK_PAGES is less than ZFS_MIN_KSTACK_PAGES (which is 4 at the time of writing). Please consider using 'options KSTACK_PAGES=X' where X is greater than or equal to ZFS_MIN_KSTACK_PAGES i.e. 4 in such configurations. 20150706: sendmail has been updated to 8.15.2. Starting with FreeBSD 11.0 and sendmail 8.15, sendmail uses uncompressed IPv6 addresses by default, i.e., they will not contain "::". For example, instead of ::1, it will be 0:0:0:0:0:0:0:1. This permits a zero subnet to have a more specific match, such as different map entries for IPv6:0:0 vs IPv6:0. This change requires that configuration data (including maps, files, classes, custom ruleset, etc.) must use the same format, so make certain such configuration data is upgrading. As a very simple check search for patterns like 'IPv6:[0-9a-fA-F:]*::' and 'IPv6::'. To return to the old behavior, set the m4 option confUSE_COMPRESSED_IPV6_ADDRESSES or the cf option UseCompressedIPv6Addresses. 20150630: The default kernel entropy-processing algorithm is now Fortuna, replacing Yarrow. Assuming you have 'device random' in your kernel config file, the configurations allow a kernel option to override this default. You may choose *ONE* of: options RANDOM_YARROW # Legacy /dev/random algorithm. options RANDOM_DUMMY # Blocking-only driver. If you have neither, you get Fortuna. For most people, read no further, Fortuna will give a /dev/random that works like it always used to, and the difference will be irrelevant. If you remove 'device random', you get *NO* kernel-processed entropy at all. This may be acceptable to folks building embedded systems, but has complications. Carry on reading, and it is assumed you know what you need. *PLEASE* read random(4) and random(9) if you are in the habit of tweaking kernel configs, and/or if you are a member of the embedded community, wanting specific and not-usual behaviour from your security subsystems. NOTE!! If you use RANDOM_DUMMY and/or have no 'device random', you will NOT have a functioning /dev/random, and many cryptographic features will not work, including SSH. You may also find strange behaviour from the random(3) set of library functions, in particular sranddev(3), srandomdev(3) and arc4random(3). The reason for this is that the KERN_ARND sysctl only returns entropy if it thinks it has some to share, and with RANDOM_DUMMY or no 'device random' this will never happen. 20150623: An additional fix for the issue described in the 20150614 sendmail entry below has been been committed in revision 284717. 20150616: FreeBSD's old make (fmake) has been removed from the system. It is available as the devel/fmake port or via pkg install fmake. 20150615: The fix for the issue described in the 20150614 sendmail entry below has been been committed in revision 284436. The work around described in that entry is no longer needed unless the default setting is overridden by a confDH_PARAMETERS configuration setting of '5' or pointing to a 512 bit DH parameter file. 20150614: ALLOW_DEPRECATED_ATF_TOOLS/ATFFILE support has been removed from atf.test.mk (included from bsd.test.mk). Please upgrade devel/atf and devel/kyua to version 0.20+ and adjust any calling code to work with Kyuafile and kyua. 20150614: The import of openssl to address the FreeBSD-SA-15:10.openssl security advisory includes a change which rejects handshakes with DH parameters below 768 bits. sendmail releases prior to 8.15.2 (not yet released), defaulted to a 512 bit DH parameter setting for client connections. To work around this interoperability, sendmail can be configured to use a 2048 bit DH parameter by: 1. Edit /etc/mail/`hostname`.mc 2. If a setting for confDH_PARAMETERS does not exist or exists and is set to a string beginning with '5', replace it with '2'. 3. If a setting for confDH_PARAMETERS exists and is set to a file path, create a new file with: openssl dhparam -out /path/to/file 2048 4. Rebuild the .cf file: cd /etc/mail/; make; make install 5. Restart sendmail: cd /etc/mail/; make restart A sendmail patch is coming, at which time this file will be updated. 20150604: Generation of legacy formatted entries have been disabled by default in pwd_mkdb(8), as all base system consumers of the legacy formatted entries were converted to use the new format by default when the new, machine independent format have been added and supported since FreeBSD 5.x. Please see the pwd_mkdb(8) manual page for further details. 20150525: Clang and llvm have been upgraded to 3.6.1 release. Please see the 20141231 entry below for information about prerequisites and upgrading, if you are not already using 3.5.0 or higher. 20150521: TI platform code switched to using vendor DTS files and this update may break existing systems running on Beaglebone, Beaglebone Black, and Pandaboard: - dtb files should be regenerated/reinstalled. Filenames are the same but content is different now - GPIO addressing was changed, now each GPIO bank (32 pins per bank) has its own /dev/gpiocX device, e.g. pin 121 on /dev/gpioc0 in old addressing scheme is now pin 25 on /dev/gpioc3. - Pandaboard: /etc/ttys should be updated, serial console device is now /dev/ttyu2, not /dev/ttyu0 20150501: soelim(1) from gnu/usr.bin/groff has been replaced by usr.bin/soelim. If you need the GNU extension from groff soelim(1), install groff from package: pkg install groff, or via ports: textproc/groff. 20150423: chmod, chflags, chown and chgrp now affect symlinks in -R mode as defined in symlink(7); previously symlinks were silently ignored. 20150415: The const qualifier has been removed from iconv(3) to comply with POSIX. The ports tree is aware of this from r384038 onwards. 20150416: Libraries specified by LIBADD in Makefiles must have a corresponding DPADD_ variable to ensure correct dependencies. This is now enforced in src.libnames.mk. 20150324: From legacy ata(4) driver was removed support for SATA controllers supported by more functional drivers ahci(4), siis(4) and mvs(4). Kernel modules ataahci and ataadaptec were removed completely, replaced by ahci and mvs modules respectively. 20150315: Clang, llvm and lldb have been upgraded to 3.6.0 release. Please see the 20141231 entry below for information about prerequisites and upgrading, if you are not already using 3.5.0 or higher. 20150307: The 32-bit PowerPC kernel has been changed to a position-independent executable. This can only be booted with a version of loader(8) newer than January 31, 2015, so make sure to update both world and kernel before rebooting. 20150217: If you are running a -CURRENT kernel since r273872 (Oct 30th, 2014), but before r278950, the RNG was not seeded properly. Immediately upgrade the kernel to r278950 or later and regenerate any keys (e.g. ssh keys or openssl keys) that were generated w/ a kernel from that range. This does not affect programs that directly used /dev/random or /dev/urandom. All userland uses of arc4random(3) are affected. 20150210: The autofs(4) ABI was changed in order to restore binary compatibility with 10.1-RELEASE. The automountd(8) daemon needs to be rebuilt to work with the new kernel. 20150131: The powerpc64 kernel has been changed to a position-independent executable. This can only be booted with a new version of loader(8), so make sure to update both world and kernel before rebooting. 20150118: Clang and llvm have been upgraded to 3.5.1 release. This is a bugfix only release, no new features have been added. Please see the 20141231 entry below for information about prerequisites and upgrading, if you are not already using 3.5.0. 20150107: ELF tools addr2line, elfcopy (strip), nm, size, and strings are now taken from the ELF Tool Chain project rather than GNU binutils. They should be drop-in replacements, with the addition of arm64 support. The WITHOUT_ELFTOOLCHAIN_TOOLS= knob may be used to obtain the binutils tools, if necessary. See 20150805 for updated information. 20150105: The default Unbound configuration now enables remote control using a local socket. Users who have already enabled the local_unbound service should regenerate their configuration by running "service local_unbound setup" as root. 20150102: The GNU texinfo and GNU info pages have been removed. To be able to view GNU info pages please install texinfo from ports. 20141231: Clang, llvm and lldb have been upgraded to 3.5.0 release. As of this release, a prerequisite for building clang, llvm and lldb is a C++11 capable compiler and C++11 standard library. This means that to be able to successfully build the cross-tools stage of buildworld, with clang as the bootstrap compiler, your system compiler or cross compiler should either be clang 3.3 or later, or gcc 4.8 or later, and your system C++ library should be libc++, or libdstdc++ from gcc 4.8 or later. On any standard FreeBSD 10.x or 11.x installation, where clang and libc++ are on by default (that is, on x86 or arm), this should work out of the box. On 9.x installations where clang is enabled by default, e.g. on x86 and powerpc, libc++ will not be enabled by default, so libc++ should be built (with clang) and installed first. If both clang and libc++ are missing, build clang first, then use it to build libc++. On 8.x and earlier installations, upgrade to 9.x first, and then follow the instructions for 9.x above. Sparc64 and mips users are unaffected, as they still use gcc 4.2.1 by default, and do not build clang. Many embedded systems are resource constrained, and will not be able to build clang in a reasonable time, or in some cases at all. In those cases, cross building bootable systems on amd64 is a workaround. This new version of clang introduces a number of new warnings, of which the following are most likely to appear: -Wabsolute-value This warns in two cases, for both C and C++: * When the code is trying to take the absolute value of an unsigned quantity, which is effectively a no-op, and almost never what was intended. The code should be fixed, if at all possible. If you are sure that the unsigned quantity can be safely cast to signed, without loss of information or undefined behavior, you can add an explicit cast, or disable the warning. * When the code is trying to take an absolute value, but the called abs() variant is for the wrong type, which can lead to truncation. If you want to disable the warning instead of fixing the code, please make sure that truncation will not occur, or it might lead to unwanted side-effects. -Wtautological-undefined-compare and -Wundefined-bool-conversion These warn when C++ code is trying to compare 'this' against NULL, while 'this' should never be NULL in well-defined C++ code. However, there is some legacy (pre C++11) code out there, which actively abuses this feature, which was less strictly defined in previous C++ versions. Squid and openjdk do this, for example. The warning can be turned off for C++98 and earlier, but compiling the code in C++11 mode might result in unexpected behavior; for example, the parts of the program that are unreachable could be optimized away. 20141222: The old NFS client and server (kernel options NFSCLIENT, NFSSERVER) kernel sources have been removed. The .h files remain, since some utilities include them. This will need to be fixed later. If "mount -t oldnfs ..." is attempted, it will fail. If the "-o" option on mountd(8), nfsd(8) or nfsstat(1) is used, the utilities will report errors. 20141121: The handling of LOCAL_LIB_DIRS has been altered to skip addition of directories to top level SUBDIR variable when their parent directory is included in LOCAL_DIRS. Users with build systems with such hierarchies and without SUBDIR entries in the parent directory Makefiles should add them or add the directories to LOCAL_DIRS. 20141109: faith(4) and faithd(8) have been removed from the base system. Faith has been obsolete for a very long time. 20141104: vt(4), the new console driver, is enabled by default. It brings support for Unicode and double-width characters, as well as support for UEFI and integration with the KMS kernel video drivers. You may need to update your console settings in /etc/rc.conf, most probably the keymap. During boot, /etc/rc.d/syscons will indicate what you need to do. vt(4) still has issues and lacks some features compared to syscons(4). See the wiki for up-to-date information: https://wiki.freebsd.org/Newcons If you want to keep using syscons(4), you can do so by adding the following line to /boot/loader.conf: kern.vty=sc 20141102: pjdfstest has been integrated into kyua as an opt-in test suite. Please see share/doc/pjdfstest/README for more details on how to execute it. 20141009: gperf has been removed from the base system for architectures that use clang. Ports that require gperf will obtain it from the devel/gperf port. 20140923: pjdfstest has been moved from tools/regression/pjdfstest to contrib/pjdfstest . 20140922: At svn r271982, The default linux compat kernel ABI has been adjusted to 2.6.18 in support of the linux-c6 compat ports infrastructure update. If you wish to continue using the linux-f10 compat ports, add compat.linux.osrelease=2.6.16 to your local sysctl.conf. Users are encouraged to update their linux-compat packages to linux-c6 during their next update cycle. 20140729: The ofwfb driver, used to provide a graphics console on PowerPC when using vt(4), no longer allows mmap() of all physical memory. This will prevent Xorg on PowerPC with some ATI graphics cards from initializing properly unless x11-servers/xorg-server is updated to 1.12.4_8 or newer. 20140723: The xdev targets have been converted to using TARGET and TARGET_ARCH instead of XDEV and XDEV_ARCH. 20140719: The default unbound configuration has been modified to address issues with reverse lookups on networks that use private address ranges. If you use the local_unbound service, run "service local_unbound setup" as root to regenerate your configuration, then "service local_unbound reload" to load the new configuration. 20140709: The GNU texinfo and GNU info pages are not built and installed anymore, WITH_INFO knob has been added to allow to built and install them again. UPDATE: see 20150102 entry on texinfo's removal 20140708: The GNU readline library is now an INTERNALLIB - that is, it is statically linked into consumers (GDB and variants) in the base system, and the shared library is no longer installed. The devel/readline port is available for third party software that requires readline. 20140702: The Itanium architecture (ia64) has been removed from the list of known architectures. This is the first step in the removal of the architecture. 20140701: Commit r268115 has added NFSv4.1 server support, merged from projects/nfsv4.1-server. Since this includes changes to the internal interfaces between the NFS related modules, a full build of the kernel and modules will be necessary. __FreeBSD_version has been bumped. 20140629: The WITHOUT_VT_SUPPORT kernel config knob has been renamed WITHOUT_VT. (The other _SUPPORT knobs have a consistent meaning which differs from the behaviour controlled by this knob.) 20140619: Maximal length of the serial number in CTL was increased from 16 to 64 chars, that breaks ABI. All CTL-related tools, such as ctladm and ctld, need to be rebuilt to work with a new kernel. 20140606: The libatf-c and libatf-c++ major versions were downgraded to 0 and 1 respectively to match the upstream numbers. They were out of sync because, when they were originally added to FreeBSD, the upstream versions were not respected. These libraries are private and not yet built by default, so renumbering them should be a non-issue. However, unclean source trees will yield broken test programs once the operator executes "make delete-old-libs" after a "make installworld". Additionally, the atf-sh binary was made private by moving it into /usr/libexec/. Already-built shell test programs will keep the path to the old binary so they will break after "make delete-old" is run. If you are using WITH_TESTS=yes (not the default), wipe the object tree and rebuild from scratch to prevent spurious test failures. This is only needed once: the misnumbered libraries and misplaced binaries have been added to OptionalObsoleteFiles.inc so they will be removed during a clean upgrade. 20140512: Clang and llvm have been upgraded to 3.4.1 release. 20140508: We bogusly installed src.opts.mk in /usr/share/mk. This file should be removed to avoid issues in the future (and has been added to ObsoleteFiles.inc). 20140505: /etc/src.conf now affects only builds of the FreeBSD src tree. In the past, it affected all builds that used the bsd.*.mk files. The old behavior was a bug, but people may have relied upon it. To get this behavior back, you can .include /etc/src.conf from /etc/make.conf (which is still global and isn't changed). This also changes the behavior of incremental builds inside the tree of individual directories. Set MAKESYSPATH to ".../share/mk" to do that. Although this has survived make universe and some upgrade scenarios, other upgrade scenarios may have broken. At least one form of temporary breakage was fixed with MAKESYSPATH settings for buildworld as well... In cases where MAKESYSPATH isn't working with this setting, you'll need to set it to the full path to your tree. One side effect of all this cleaning up is that bsd.compiler.mk is no longer implicitly included by bsd.own.mk. If you wish to use COMPILER_TYPE, you must now explicitly include bsd.compiler.mk as well. 20140430: The lindev device has been removed since /dev/full has been made a standard device. __FreeBSD_version has been bumped. 20140424: The knob WITHOUT_VI was added to the base system, which controls building ex(1), vi(1), etc. Older releases of FreeBSD required ex(1) in order to reorder files share/termcap and didn't build ex(1) as a build tool, so building/installing with WITH_VI is highly advised for build hosts for older releases. This issue has been fixed in stable/9 and stable/10 in r277022 and r276991, respectively. 20140418: The YES_HESIOD knob has been removed. It has been obsolete for a decade. Please move to using WITH_HESIOD instead or your builds will silently lack HESIOD. 20140405: The uart(4) driver has been changed with respect to its handling of the low-level console. Previously the uart(4) driver prevented any process from changing the baudrate or the CLOCAL and HUPCL control flags. By removing the restrictions, operators can make changes to the serial console port without having to reboot. However, when getty(8) is started on the serial device that is associated with the low-level console, a misconfigured terminal line in /etc/ttys will now have a real impact. Before upgrading the kernel, make sure that /etc/ttys has the serial console device configured as 3wire without baudrate to preserve the previous behaviour. E.g: ttyu0 "/usr/libexec/getty 3wire" vt100 on secure 20140306: Support for libwrap (TCP wrappers) in rpcbind was disabled by default to improve performance. To re-enable it, if needed, run rpcbind with command line option -W. 20140226: Switched back to the GPL dtc compiler due to updates in the upstream dts files not being supported by the BSDL dtc compiler. You will need to rebuild your kernel toolchain to pick up the new compiler. Core dumps may result while building dtb files during a kernel build if you fail to do so. Set WITHOUT_GPL_DTC if you require the BSDL compiler. 20140216: Clang and llvm have been upgraded to 3.4 release. 20140216: The nve(4) driver has been removed. Please use the nfe(4) driver for NVIDIA nForce MCP Ethernet adapters instead. 20140212: An ABI incompatibility crept into the libc++ 3.4 import in r261283. This could cause certain C++ applications using shared libraries built against the previous version of libc++ to crash. The incompatibility has now been fixed, but any C++ applications or shared libraries built between r261283 and r261801 should be recompiled. 20140204: OpenSSH will now ignore errors caused by kernel lacking of Capsicum capability mode support. Please note that enabling the feature in kernel is still highly recommended. 20140131: OpenSSH is now built with sandbox support, and will use sandbox as the default privilege separation method. This requires Capsicum capability mode support in kernel. 20140128: The libelf and libdwarf libraries have been updated to newer versions from upstream. Shared library version numbers for these two libraries were bumped. Any ports or binaries requiring these two libraries should be recompiled. __FreeBSD_version is bumped to 1100006. 20140110: If a Makefile in a tests/ directory was auto-generating a Kyuafile instead of providing an explicit one, this would prevent such Makefile from providing its own Kyuafile in the future during NO_CLEAN builds. This has been fixed in the Makefiles but manual intervention is needed to clean an objdir if you use NO_CLEAN: # find /usr/obj -name Kyuafile | xargs rm -f 20131213: The behavior of gss_pseudo_random() for the krb5 mechanism has changed, for applications requesting a longer random string than produced by the underlying enctype's pseudo-random() function. In particular, the random string produced from a session key of enctype aes256-cts-hmac-sha1-96 or aes256-cts-hmac-sha1-96 will be different at the 17th octet and later, after this change. The counter used in the PRF+ construction is now encoded as a big-endian integer in accordance with RFC 4402. __FreeBSD_version is bumped to 1100004. 20131108: The WITHOUT_ATF build knob has been removed and its functionality has been subsumed into the more generic WITHOUT_TESTS. If you were using the former to disable the build of the ATF libraries, you should change your settings to use the latter. 20131025: The default version of mtree is nmtree which is obtained from NetBSD. The output is generally the same, but may vary slightly. If you found you need identical output adding "-F freebsd9" to the command line should do the trick. For the time being, the old mtree is available as fmtree. 20131014: libbsdyml has been renamed to libyaml and moved to /usr/lib/private. This will break ports-mgmt/pkg. Rebuild the port, or upgrade to pkg 1.1.4_8 and verify bsdyml not linked in, before running "make delete-old-libs": # make -C /usr/ports/ports-mgmt/pkg build deinstall install clean or # pkg install pkg; ldd /usr/local/sbin/pkg | grep bsdyml 20131010: The stable/10 branch has been created in subversion from head revision r256279. 20131010: The rc.d/jail script has been updated to support jail(8) configuration file. The "jail__*" rc.conf(5) variables for per-jail configuration are automatically converted to /var/run/jail..conf before the jail(8) utility is invoked. This is transparently backward compatible. See below about some incompatibilities and rc.conf(5) manual page for more details. These variables are now deprecated in favor of jail(8) configuration file. One can use "rc.d/jail config " command to generate a jail(8) configuration file in /var/run/jail..conf without running the jail(8) utility. The default pathname of the configuration file is /etc/jail.conf and can be specified by using $jail_conf or $jail__conf variables. Please note that jail_devfs_ruleset accepts an integer at this moment. Please consider to rewrite the ruleset name with an integer. 20130930: BIND has been removed from the base system. If all you need is a local resolver, simply enable and start the local_unbound service instead. Otherwise, several versions of BIND are available in the ports tree. The dns/bind99 port is one example. With this change, nslookup(1) and dig(1) are no longer in the base system. Users should instead use host(1) and drill(1) which are in the base system. Alternatively, nslookup and dig can be obtained by installing the dns/bind-tools port. 20130916: With the addition of unbound(8), a new unbound user is now required during installworld. "mergemaster -p" can be used to add the user prior to installworld, as documented in the handbook. 20130911: OpenSSH is now built with DNSSEC support, and will by default silently trust signed SSHFP records. This can be controlled with the VerifyHostKeyDNS client configuration setting. DNSSEC support can be disabled entirely with the WITHOUT_LDNS option in src.conf. 20130906: The GNU Compiler Collection and C++ standard library (libstdc++) are no longer built by default on platforms where clang is the system compiler. You can enable them with the WITH_GCC and WITH_GNUCXX options in src.conf. 20130905: The PROCDESC kernel option is now part of the GENERIC kernel configuration and is required for the rwhod(8) to work. If you are using custom kernel configuration, you should include 'options PROCDESC'. 20130905: The API and ABI related to the Capsicum framework was modified in backward incompatible way. The userland libraries and programs have to be recompiled to work with the new kernel. This includes the following libraries and programs, but the whole buildworld is advised: libc, libprocstat, dhclient, tcpdump, hastd, hastctl, kdump, procstat, rwho, rwhod, uniq. 20130903: AES-NI intrinsic support has been added to gcc. The AES-NI module has been updated to use this support. A new gcc is required to build the aesni module on both i386 and amd64. 20130821: The PADLOCK_RNG and RDRAND_RNG kernel options are now devices. Thus "device padlock_rng" and "device rdrand_rng" should be used instead of "options PADLOCK_RNG" & "options RDRAND_RNG". 20130813: WITH_ICONV has been split into two feature sets. WITH_ICONV now enables just the iconv* functionality and is now on by default. WITH_LIBICONV_COMPAT enables the libiconv api and link time compatability. Set WITHOUT_ICONV to build the old way. If you have been using WITH_ICONV before, you will very likely need to turn on WITH_LIBICONV_COMPAT. 20130806: INVARIANTS option now enables DEBUG for code with OpenSolaris and Illumos origin, including ZFS. If you have INVARIANTS in your kernel configuration, then there is no need to set DEBUG or ZFS_DEBUG explicitly. DEBUG used to enable witness(9) tracking of OpenSolaris (mostly ZFS) locks if WITNESS option was set. Because that generated a lot of witness(9) reports and all of them were believed to be false positives, this is no longer done. New option OPENSOLARIS_WITNESS can be used to achieve the previous behavior. 20130806: Timer values in IPv6 data structures now use time_uptime instead of time_second. Although this is not a user-visible functional change, userland utilities which directly use them---ndp(8), rtadvd(8), and rtsold(8) in the base system---need to be updated to r253970 or later. 20130802: find -delete can now delete the pathnames given as arguments, instead of only files found below them or if the pathname did not contain any slashes. Formerly, the following error message would result: find: -delete: : relative path potentially not safe Deleting the pathnames given as arguments can be prevented without error messages using -mindepth 1 or by changing directory and passing "." as argument to find. This works in the old as well as the new version of find. 20130726: Behavior of devfs rules path matching has been changed. Pattern is now always matched against fully qualified devfs path and slash characters must be explicitly matched by slashes in pattern (FNM_PATHNAME). Rulesets involving devfs subdirectories must be reviewed. 20130716: The default ARM ABI has changed to the ARM EABI. The old ABI is incompatible with the ARM EABI and all programs and modules will need to be rebuilt to work with a new kernel. To keep using the old ABI ensure the WITHOUT_ARM_EABI knob is set. NOTE: Support for the old ABI will be removed in the future and users are advised to upgrade. 20130709: pkg_install has been disconnected from the build if you really need it you should add WITH_PKGTOOLS in your src.conf(5). 20130709: Most of network statistics structures were changed to be able keep 64-bits counters. Thus all tools, that work with networking statistics, must be rebuilt (netstat(1), bsnmpd(1), etc.) 20130618: Fix a bug that allowed a tracing process (e.g. gdb) to write to a memory-mapped file in the traced process's address space even if neither the traced process nor the tracing process had write access to that file. 20130615: CVS has been removed from the base system. An exact copy of the code is available from the devel/cvs port. 20130613: Some people report the following error after the switch to bmake: make: illegal option -- J usage: make [-BPSXeiknpqrstv] [-C directory] [-D variable] ... *** [buildworld] Error code 2 this likely due to an old instance of make in ${MAKEPATH} (${MAKEOBJDIRPREFIX}${.CURDIR}/make.${MACHINE}) which src/Makefile will use that blindly, if it exists, so if you see the above error: rm -rf `make -V MAKEPATH` should resolve it. 20130516: Use bmake by default. Whereas before one could choose to build with bmake via -DWITH_BMAKE one must now use -DWITHOUT_BMAKE to use the old make. The goal is to remove these knobs for 10-RELEASE. It is worth noting that bmake (like gmake) treats the command line as the unit of failure, rather than statements within the command line. Thus '(cd some/where && dosomething)' is safer than 'cd some/where; dosomething'. The '()' allows consistent behavior in parallel build. 20130429: Fix a bug that allows NFS clients to issue READDIR on files. 20130426: The WITHOUT_IDEA option has been removed because the IDEA patent expired. 20130426: The sysctl which controls TRIM support under ZFS has been renamed from vfs.zfs.trim_disable -> vfs.zfs.trim.enabled and has been enabled by default. 20130425: The mergemaster command now uses the default MAKEOBJDIRPREFIX rather than creating it's own in the temporary directory in order allow access to bootstrapped versions of tools such as install and mtree. When upgrading from version of FreeBSD where the install command does not support -l, you will need to install a new mergemaster command if mergemaster -p is required. This can be accomplished with the command (cd src/usr.sbin/mergemaster && make install). 20130404: Legacy ATA stack, disabled and replaced by new CAM-based one since FreeBSD 9.0, completely removed from the sources. Kernel modules atadisk and atapi*, user-level tools atacontrol and burncd are removed. Kernel option `options ATA_CAM` is now permanently enabled and removed. 20130319: SOCK_CLOEXEC and SOCK_NONBLOCK flags have been added to socket(2) and socketpair(2). Software, in particular Kerberos, may automatically detect and use these during building. The resulting binaries will not work on older kernels. 20130308: CTL_DISABLE has also been added to the sparc64 GENERIC (for further information, see the respective 20130304 entry). 20130304: Recent commits to callout(9) changed the size of struct callout, so the KBI is probably heavily disturbed. Also, some functions in callout(9)/sleep(9)/sleepqueue(9)/condvar(9) KPIs were replaced by macros. Every kernel module using it won't load, so rebuild is requested. The ctl device has been re-enabled in GENERIC for i386 and amd64, but does not initialize by default (because of the new CTL_DISABLE option) to save memory. To re-enable it, remove the CTL_DISABLE option from the kernel config file or set kern.cam.ctl.disable=0 in /boot/loader.conf. 20130301: The ctl device has been disabled in GENERIC for i386 and amd64. This was done due to the extra memory being allocated at system initialisation time by the ctl driver which was only used if a CAM target device was created. This makes a FreeBSD system unusable on 128MB or less of RAM. 20130208: A new compression method (lz4) has been merged to -HEAD. Please refer to zpool-features(7) for more information. Please refer to the "ZFS notes" section of this file for information on upgrading boot ZFS pools. 20130129: A BSD-licensed patch(1) variant has been added and is installed as bsdpatch, being the GNU version the default patch. To inverse the logic and use the BSD-licensed one as default, while having the GNU version installed as gnupatch, rebuild and install world with the WITH_BSD_PATCH knob set. 20130121: Due to the use of the new -l option to install(1) during build and install, you must take care not to directly set the INSTALL make variable in your /etc/make.conf, /etc/src.conf, or on the command line. If you wish to use the -C flag for all installs you may be able to add INSTALL+=-C to /etc/make.conf or /etc/src.conf. 20130118: The install(1) option -M has changed meaning and now takes an argument that is a file or path to append logs to. In the unlikely event that -M was the last option on the command line and the command line contained at least two files and a target directory the first file will have logs appended to it. The -M option served little practical purpose in the last decade so its use is expected to be extremely rare. 20121223: After switching to Clang as the default compiler some users of ZFS on i386 systems started to experience stack overflow kernel panics. Please consider using 'options KSTACK_PAGES=4' in such configurations. 20121222: GEOM_LABEL now mangles label names read from file system metadata. Mangling affect labels containing spaces, non-printable characters, '%' or '"'. Device names in /etc/fstab and other places may need to be updated. 20121217: By default, only the 10 most recent kernel dumps will be saved. To restore the previous behaviour (no limit on the number of kernel dumps stored in the dump directory) add the following line to /etc/rc.conf: savecore_flags="" 20121201: With the addition of auditdistd(8), a new auditdistd user is now required during installworld. "mergemaster -p" can be used to add the user prior to installworld, as documented in the handbook. 20121117: The sin6_scope_id member variable in struct sockaddr_in6 is now filled by the kernel before passing the structure to the userland via sysctl or routing socket. This means the KAME-specific embedded scope id in sin6_addr.s6_addr[2] is always cleared in userland application. This behavior can be controlled by net.inet6.ip6.deembed_scopeid. __FreeBSD_version is bumped to 1000025. 20121105: On i386 and amd64 systems WITH_CLANG_IS_CC is now the default. This means that the world and kernel will be compiled with clang and that clang will be installed as /usr/bin/cc, /usr/bin/c++, and /usr/bin/cpp. To disable this behavior and revert to building with gcc, compile with WITHOUT_CLANG_IS_CC. Really old versions of current may need to bootstrap WITHOUT_CLANG first if the clang build fails (its compatibility window doesn't extend to the 9 stable branch point). 20121102: The IPFIREWALL_FORWARD kernel option has been removed. Its functionality now turned on by default. 20121023: The ZERO_COPY_SOCKET kernel option has been removed and split into SOCKET_SEND_COW and SOCKET_RECV_PFLIP. NB: SOCKET_SEND_COW uses the VM page based copy-on-write mechanism which is not safe and may result in kernel crashes. NB: The SOCKET_RECV_PFLIP mechanism is useless as no current driver supports disposeable external page sized mbuf storage. Proper replacements for both zero-copy mechanisms are under consideration and will eventually lead to complete removal of the two kernel options. 20121023: The IPv4 network stack has been converted to network byte order. The following modules need to be recompiled together with kernel: carp(4), divert(4), gif(4), siftr(4), gre(4), pf(4), ipfw(4), ng_ipfw(4), stf(4). 20121022: Support for non-MPSAFE filesystems was removed from VFS. The VFS_VERSION was bumped, all filesystem modules shall be recompiled. 20121018: All the non-MPSAFE filesystems have been disconnected from the build. The full list includes: codafs, hpfs, ntfs, nwfs, portalfs, smbfs, xfs. 20121016: The interface cloning API and ABI has changed. The following modules need to be recompiled together with kernel: ipfw(4), pfsync(4), pflog(4), usb(4), wlan(4), stf(4), vlan(4), disc(4), edsc(4), if_bridge(4), gif(4), tap(4), faith(4), epair(4), enc(4), tun(4), if_lagg(4), gre(4). 20121015: The sdhci driver was split in two parts: sdhci (generic SD Host Controller logic) and sdhci_pci (actual hardware driver). No kernel config modifications are required, but if you load sdhc as a module you must switch to sdhci_pci instead. 20121014: Import the FUSE kernel and userland support into base system. 20121013: The GNU sort(1) program has been removed since the BSD-licensed sort(1) has been the default for quite some time and no serious problems have been reported. The corresponding WITH_GNU_SORT knob has also gone. 20121006: The pfil(9) API/ABI for AF_INET family has been changed. Packet filtering modules: pf(4), ipfw(4), ipfilter(4) need to be recompiled with new kernel. 20121001: The net80211(4) ABI has been changed to allow for improved driver PS-POLL and power-save support. All wireless drivers need to be recompiled to work with the new kernel. 20120913: The random(4) support for the VIA hardware random number generator (`PADLOCK') is no longer enabled unconditionally. Add the padlock_rng device in the custom kernel config if needed. The GENERIC kernels on i386 and amd64 do include the device, so the change only affects the custom kernel configurations. 20120908: The pf(4) packet filter ABI has been changed. pfctl(8) and snmp_pf module need to be recompiled to work with new kernel. 20120828: A new ZFS feature flag "com.delphix:empty_bpobj" has been merged to -HEAD. Pools that have empty_bpobj in active state can not be imported read-write with ZFS implementations that do not support this feature. For more information read the zpool-features(5) manual page. 20120727: The sparc64 ZFS loader has been changed to no longer try to auto- detect ZFS providers based on diskN aliases but now requires these to be explicitly listed in the OFW boot-device environment variable. 20120712: The OpenSSL has been upgraded to 1.0.1c. Any binaries requiring libcrypto.so.6 or libssl.so.6 must be recompiled. Also, there are configuration changes. Make sure to merge /etc/ssl/openssl.cnf. 20120712: The following sysctls and tunables have been renamed for consistency with other variables: kern.cam.da.da_send_ordered -> kern.cam.da.send_ordered kern.cam.ada.ada_send_ordered -> kern.cam.ada.send_ordered 20120628: The sort utility has been replaced with BSD sort. For now, GNU sort is also available as "gnusort" or the default can be set back to GNU sort by setting WITH_GNU_SORT. In this case, BSD sort will be installed as "bsdsort". 20120611: A new version of ZFS (pool version 5000) has been merged to -HEAD. Starting with this version the old system of ZFS pool versioning is superseded by "feature flags". This concept enables forward compatibility against certain future changes in functionality of ZFS pools. The first read-only compatible "feature flag" for ZFS pools is named "com.delphix:async_destroy". For more information read the new zpool-features(5) manual page. Please refer to the "ZFS notes" section of this file for information on upgrading boot ZFS pools. 20120417: The malloc(3) implementation embedded in libc now uses sources imported as contrib/jemalloc. The most disruptive API change is to /etc/malloc.conf. If your system has an old-style /etc/malloc.conf, delete it prior to installworld, and optionally re-create it using the new format after rebooting. See malloc.conf(5) for details (specifically the TUNING section and the "opt.*" entries in the MALLCTL NAMESPACE section). 20120328: Big-endian MIPS TARGET_ARCH values no longer end in "eb". mips64eb is now spelled mips64. mipsn32eb is now spelled mipsn32. mipseb is now spelled mips. This is to aid compatibility with third-party software that expects this naming scheme in uname(3). Little-endian settings are unchanged. If you are updating a big-endian mips64 machine from before this change, you may need to set MACHINE_ARCH=mips64 in your environment before the new build system will recognize your machine. 20120306: Disable by default the option VFS_ALLOW_NONMPSAFE for all supported platforms. 20120229: Now unix domain sockets behave "as expected" on nullfs(5). Previously nullfs(5) did not pass through all behaviours to the underlying layer, as a result if we bound to a socket on the lower layer we could connect only to the lower path; if we bound to the upper layer we could connect only to the upper path. The new behavior is one can connect to both the lower and the upper paths regardless what layer path one binds to. 20120211: The getifaddrs upgrade path broken with 20111215 has been restored. If you have upgraded in between 20111215 and 20120209 you need to recompile libc again with your kernel. You still need to recompile world to be able to configure CARP but this restriction already comes from 20111215. 20120114: The set_rcvar() function has been removed from /etc/rc.subr. All base and ports rc.d scripts have been updated, so if you have a port installed with a script in /usr/local/etc/rc.d you can either hand-edit the rcvar= line, or reinstall the port. An easy way to handle the mass-update of /etc/rc.d: rm /etc/rc.d/* && mergemaster -i 20120109: panic(9) now stops other CPUs in the SMP systems, disables interrupts on the current CPU and prevents other threads from running. This behavior can be reverted using the kern.stop_scheduler_on_panic tunable/sysctl. The new behavior can be incompatible with kern.sync_on_panic. 20111215: The carp(4) facility has been changed significantly. Configuration of the CARP protocol via ifconfig(8) has changed, as well as format of CARP events submitted to devd(8) has changed. See manual pages for more information. The arpbalance feature of carp(4) is currently not supported anymore. Size of struct in_aliasreq, struct in6_aliasreq has changed. User utilities using SIOCAIFADDR, SIOCAIFADDR_IN6, e.g. ifconfig(8), need to be recompiled. 20111122: The acpi_wmi(4) status device /dev/wmistat has been renamed to /dev/wmistat0. 20111108: The option VFS_ALLOW_NONMPSAFE option has been added in order to explicitely support non-MPSAFE filesystems. It is on by default for all supported platform at this present time. 20111101: The broken amd(4) driver has been replaced with esp(4) in the amd64, i386 and pc98 GENERIC kernel configuration files. 20110930: sysinstall has been removed 20110923: The stable/9 branch created in subversion. This corresponds to the RELENG_9 branch in CVS. COMMON ITEMS: General Notes ------------- Avoid using make -j when upgrading. While generally safe, there are sometimes problems using -j to upgrade. If your upgrade fails with -j, please try again without -j. From time to time in the past there have been problems using -j with buildworld and/or installworld. This is especially true when upgrading between "distant" versions (eg one that cross a major release boundary or several minor releases, or when several months have passed on the -current branch). Sometimes, obscure build problems are the result of environment poisoning. This can happen because the make utility reads its environment when searching for values for global variables. To run your build attempts in an "environmental clean room", prefix all make commands with 'env -i '. See the env(1) manual page for more details. When upgrading from one major version to another it is generally best to upgrade to the latest code in the currently installed branch first, then do an upgrade to the new branch. This is the best-tested upgrade path, and has the highest probability of being successful. Please try this approach before reporting problems with a major version upgrade. When upgrading a live system, having a root shell around before installing anything can help undo problems. Not having a root shell around can lead to problems if pam has changed too much from your starting point to allow continued authentication after the upgrade. This file should be read as a log of events. When a later event changes information of a prior event, the prior event should not be deleted. Instead, a pointer to the entry with the new information should be placed in the old entry. Readers of this file should also sanity check older entries before relying on them blindly. Authors of new entries should write them with this in mind. ZFS notes --------- When upgrading the boot ZFS pool to a new version, always follow these two steps: 1.) recompile and reinstall the ZFS boot loader and boot block (this is part of "make buildworld" and "make installworld") 2.) update the ZFS boot block on your boot drive The following example updates the ZFS boot block on the first partition (freebsd-boot) of a GPT partitioned drive ada0: "gpart bootcode -p /boot/gptzfsboot -i 1 ada0" Non-boot pools do not need these updates. To build a kernel ----------------- If you are updating from a prior version of FreeBSD (even one just a few days old), you should follow this procedure. It is the most failsafe as it uses a /usr/obj tree with a fresh mini-buildworld, make kernel-toolchain make -DALWAYS_CHECK_MAKE buildkernel KERNCONF=YOUR_KERNEL_HERE make -DALWAYS_CHECK_MAKE installkernel KERNCONF=YOUR_KERNEL_HERE To test a kernel once --------------------- If you just want to boot a kernel once (because you are not sure if it works, or if you want to boot a known bad kernel to provide debugging information) run make installkernel KERNCONF=YOUR_KERNEL_HERE KODIR=/boot/testkernel nextboot -k testkernel To just build a kernel when you know that it won't mess you up -------------------------------------------------------------- This assumes you are already running a CURRENT system. Replace ${arch} with the architecture of your machine (e.g. "i386", "arm", "amd64", "ia64", "pc98", "sparc64", "powerpc", "mips", etc). cd src/sys/${arch}/conf config KERNEL_NAME_HERE cd ../compile/KERNEL_NAME_HERE make depend make make install If this fails, go to the "To build a kernel" section. To rebuild everything and install it on the current system. ----------------------------------------------------------- # Note: sometimes if you are running current you gotta do more than # is listed here if you are upgrading from a really old current. make buildworld make kernel KERNCONF=YOUR_KERNEL_HERE [1] [3] mergemaster -Fp [5] make installworld mergemaster -Fi [4] make delete-old [6] To cross-install current onto a separate partition -------------------------------------------------- # In this approach we use a separate partition to hold # current's root, 'usr', and 'var' directories. A partition # holding "/", "/usr" and "/var" should be about 2GB in # size. make buildworld make buildkernel KERNCONF=YOUR_KERNEL_HERE make installworld DESTDIR=${CURRENT_ROOT} -DDB_FROM_SRC make distribution DESTDIR=${CURRENT_ROOT} # if newfs'd make installkernel KERNCONF=YOUR_KERNEL_HERE DESTDIR=${CURRENT_ROOT} cp /etc/fstab ${CURRENT_ROOT}/etc/fstab # if newfs'd To upgrade in-place from stable to current ---------------------------------------------- make buildworld [9] make kernel KERNCONF=YOUR_KERNEL_HERE [8] [1] [3] mergemaster -Fp [5] make installworld mergemaster -Fi [4] make delete-old [6] Make sure that you've read the UPDATING file to understand the tweaks to various things you need. At this point in the life cycle of current, things change often and you are on your own to cope. The defaults can also change, so please read ALL of the UPDATING entries. Also, if you are tracking -current, you must be subscribed to freebsd-current@freebsd.org. Make sure that before you update your sources that you have read and understood all the recent messages there. If in doubt, please track -stable which has much fewer pitfalls. [1] If you have third party modules, such as vmware, you should disable them at this point so they don't crash your system on reboot. [3] From the bootblocks, boot -s, and then do fsck -p mount -u / mount -a cd src adjkerntz -i # if CMOS is wall time Also, when doing a major release upgrade, it is required that you boot into single user mode to do the installworld. [4] Note: This step is non-optional. Failure to do this step can result in a significant reduction in the functionality of the system. Attempting to do it by hand is not recommended and those that pursue this avenue should read this file carefully, as well as the archives of freebsd-current and freebsd-hackers mailing lists for potential gotchas. The -U option is also useful to consider. See mergemaster(8) for more information. [5] Usually this step is a noop. However, from time to time you may need to do this if you get unknown user in the following step. It never hurts to do it all the time. You may need to install a new mergemaster (cd src/usr.sbin/mergemaster && make install) after the buildworld before this step if you last updated from current before 20130425 or from -stable before 20130430. [6] This only deletes old files and directories. Old libraries can be deleted by "make delete-old-libs", but you have to make sure that no program is using those libraries anymore. [8] In order to have a kernel that can run the 4.x binaries needed to do an installworld, you must include the COMPAT_FREEBSD4 option in your kernel. Failure to do so may leave you with a system that is hard to boot to recover. A similar kernel option COMPAT_FREEBSD5 is required to run the 5.x binaries on more recent kernels. And so on for COMPAT_FREEBSD6 and COMPAT_FREEBSD7. Make sure that you merge any new devices from GENERIC since the last time you updated your kernel config file. [9] When checking out sources, you must include the -P flag to have cvs prune empty directories. If CPUTYPE is defined in your /etc/make.conf, make sure to use the "?=" instead of the "=" assignment operator, so that buildworld can override the CPUTYPE if it needs to. MAKEOBJDIRPREFIX must be defined in an environment variable, and not on the command line, or in /etc/make.conf. buildworld will warn if it is improperly defined. FORMAT: This file contains a list, in reverse chronological order, of major breakages in tracking -current. It is not guaranteed to be a complete list of such breakages, and only contains entries since September 23, 2011. If you need to see UPDATING entries from before that date, you will need to fetch an UPDATING file from an older FreeBSD release. Copyright information: Copyright 1998-2009 M. Warner Losh. All Rights Reserved. Redistribution, publication, translation and use, with or without modification, in full or in part, in any form or format of this document are permitted without further permission from the author. THIS DOCUMENT IS PROVIDED BY WARNER LOSH ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WARNER LOSH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Contact Warner Losh if you have any questions about your use of this document. $FreeBSD$ Index: head/crypto/openssh/myproposal.h =================================================================== --- head/crypto/openssh/myproposal.h (revision 294494) +++ head/crypto/openssh/myproposal.h (revision 294495) @@ -1,195 +1,198 @@ /* $OpenBSD: myproposal.h,v 1.47 2015/07/10 06:21:53 markus Exp $ */ +/* $FreeBSD$ */ /* * Copyright (c) 2000 Markus Friedl. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include /* conditional algorithm support */ #ifdef OPENSSL_HAS_ECC #ifdef OPENSSL_HAS_NISTP521 # define KEX_ECDH_METHODS \ "ecdh-sha2-nistp256," \ "ecdh-sha2-nistp384," \ "ecdh-sha2-nistp521," # define HOSTKEY_ECDSA_CERT_METHODS \ "ecdsa-sha2-nistp256-cert-v01@openssh.com," \ "ecdsa-sha2-nistp384-cert-v01@openssh.com," \ "ecdsa-sha2-nistp521-cert-v01@openssh.com," # define HOSTKEY_ECDSA_METHODS \ "ecdsa-sha2-nistp256," \ "ecdsa-sha2-nistp384," \ "ecdsa-sha2-nistp521," #else # define KEX_ECDH_METHODS \ "ecdh-sha2-nistp256," \ "ecdh-sha2-nistp384," # define HOSTKEY_ECDSA_CERT_METHODS \ "ecdsa-sha2-nistp256-cert-v01@openssh.com," \ "ecdsa-sha2-nistp384-cert-v01@openssh.com," # define HOSTKEY_ECDSA_METHODS \ "ecdsa-sha2-nistp256," \ "ecdsa-sha2-nistp384," #endif #else # define KEX_ECDH_METHODS # define HOSTKEY_ECDSA_CERT_METHODS # define HOSTKEY_ECDSA_METHODS #endif #ifdef OPENSSL_HAVE_EVPGCM # define AESGCM_CIPHER_MODES \ ",aes128-gcm@openssh.com,aes256-gcm@openssh.com" #else # define AESGCM_CIPHER_MODES #endif #ifdef HAVE_EVP_SHA256 # define KEX_SHA256_METHODS \ "diffie-hellman-group-exchange-sha256," #define SHA2_HMAC_MODES \ "hmac-sha2-256," \ "hmac-sha2-512," #else # define KEX_SHA256_METHODS # define SHA2_HMAC_MODES #endif #ifdef WITH_OPENSSL # ifdef HAVE_EVP_SHA256 # define KEX_CURVE25519_METHODS "curve25519-sha256@libssh.org," # else # define KEX_CURVE25519_METHODS "" # endif #define KEX_COMMON_KEX \ KEX_CURVE25519_METHODS \ KEX_ECDH_METHODS \ KEX_SHA256_METHODS #define KEX_SERVER_KEX KEX_COMMON_KEX \ "diffie-hellman-group14-sha1" \ #define KEX_CLIENT_KEX KEX_COMMON_KEX \ "diffie-hellman-group-exchange-sha1," \ "diffie-hellman-group14-sha1" #define KEX_DEFAULT_PK_ALG \ HOSTKEY_ECDSA_CERT_METHODS \ "ssh-ed25519-cert-v01@openssh.com," \ "ssh-rsa-cert-v01@openssh.com," \ + "ssh-dss-cert-v01@openssh.com," \ HOSTKEY_ECDSA_METHODS \ "ssh-ed25519," \ - "ssh-rsa" \ + "ssh-rsa," \ + "ssh-dss" /* the actual algorithms */ #define KEX_SERVER_ENCRYPT \ "chacha20-poly1305@openssh.com," \ "aes128-ctr,aes192-ctr,aes256-ctr" \ AESGCM_CIPHER_MODES #define KEX_CLIENT_ENCRYPT KEX_SERVER_ENCRYPT "," \ "arcfour256,arcfour128," \ "aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc," \ "aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se" #define KEX_SERVER_MAC \ "umac-64-etm@openssh.com," \ "umac-128-etm@openssh.com," \ "hmac-sha2-256-etm@openssh.com," \ "hmac-sha2-512-etm@openssh.com," \ "hmac-sha1-etm@openssh.com," \ "umac-64@openssh.com," \ "umac-128@openssh.com," \ "hmac-sha2-256," \ "hmac-sha2-512," \ "hmac-sha1" #define KEX_CLIENT_MAC KEX_SERVER_MAC "," \ "hmac-md5-etm@openssh.com," \ "hmac-ripemd160-etm@openssh.com," \ "hmac-sha1-96-etm@openssh.com," \ "hmac-md5-96-etm@openssh.com," \ "hmac-md5," \ "hmac-ripemd160," \ "hmac-ripemd160@openssh.com," \ "hmac-sha1-96," \ "hmac-md5-96" #else #define KEX_SERVER_KEX \ "curve25519-sha256@libssh.org" #define KEX_DEFAULT_PK_ALG \ "ssh-ed25519-cert-v01@openssh.com," \ "ssh-ed25519" #define KEX_SERVER_ENCRYPT \ "chacha20-poly1305@openssh.com," \ "aes128-ctr,aes192-ctr,aes256-ctr" #define KEX_SERVER_MAC \ "umac-64-etm@openssh.com," \ "umac-128-etm@openssh.com," \ "hmac-sha2-256-etm@openssh.com," \ "hmac-sha2-512-etm@openssh.com," \ "hmac-sha1-etm@openssh.com," \ "umac-64@openssh.com," \ "umac-128@openssh.com," \ "hmac-sha2-256," \ "hmac-sha2-512," \ "hmac-sha1" #define KEX_CLIENT_KEX KEX_SERVER_KEX #define KEX_CLIENT_ENCRYPT KEX_SERVER_ENCRYPT #define KEX_CLIENT_MAC KEX_SERVER_MAC #endif /* WITH_OPENSSL */ #define KEX_DEFAULT_COMP "none,zlib@openssh.com,zlib" #define KEX_DEFAULT_LANG "" #define KEX_CLIENT \ KEX_CLIENT_KEX, \ KEX_DEFAULT_PK_ALG, \ KEX_CLIENT_ENCRYPT, \ KEX_CLIENT_ENCRYPT, \ KEX_CLIENT_MAC, \ KEX_CLIENT_MAC, \ KEX_DEFAULT_COMP, \ KEX_DEFAULT_COMP, \ KEX_DEFAULT_LANG, \ KEX_DEFAULT_LANG #define KEX_SERVER \ KEX_SERVER_KEX, \ KEX_DEFAULT_PK_ALG, \ KEX_SERVER_ENCRYPT, \ KEX_SERVER_ENCRYPT, \ KEX_SERVER_MAC, \ KEX_SERVER_MAC, \ KEX_DEFAULT_COMP, \ KEX_DEFAULT_COMP, \ KEX_DEFAULT_LANG, \ KEX_DEFAULT_LANG Property changes on: head/crypto/openssh/myproposal.h ___________________________________________________________________ Added: svn:keywords ## -0,0 +1 ## +FreeBSD=%H \ No newline at end of property Index: head/crypto/openssh/ssh_config.5 =================================================================== --- head/crypto/openssh/ssh_config.5 (revision 294494) +++ head/crypto/openssh/ssh_config.5 (revision 294495) @@ -1,1738 +1,1744 @@ .\" .\" Author: Tatu Ylonen .\" Copyright (c) 1995 Tatu Ylonen , Espoo, Finland .\" All rights reserved .\" .\" As far as I am concerned, the code I have written for this software .\" can be used freely for any purpose. Any derived versions of this .\" software must be clearly marked as such, and if the derived work is .\" incompatible with the protocol description in the RFC file, it must be .\" called by a name other than "ssh" or "Secure Shell". .\" .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved. .\" Copyright (c) 1999 Aaron Campbell. All rights reserved. .\" Copyright (c) 1999 Theo de Raadt. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" .\" $OpenBSD: ssh_config.5,v 1.214 2015/07/30 00:01:34 djm Exp $ .\" $FreeBSD$ .Dd $Mdocdate: July 30 2015 $ .Dt SSH_CONFIG 5 .Os .Sh NAME .Nm ssh_config .Nd OpenSSH SSH client configuration files .Sh SYNOPSIS .Nm ~/.ssh/config .Nm /etc/ssh/ssh_config .Sh DESCRIPTION .Xr ssh 1 obtains configuration data from the following sources in the following order: .Pp .Bl -enum -offset indent -compact .It command-line options .It user's configuration file .Pq Pa ~/.ssh/config .It system-wide configuration file .Pq Pa /etc/ssh/ssh_config .El .Pp For each parameter, the first obtained value will be used. The configuration files contain sections separated by .Dq Host specifications, and that section is only applied for hosts that match one of the patterns given in the specification. The matched host name is usually the one given on the command line (see the .Cm CanonicalizeHostname option for exceptions.) .Pp Since the first obtained value for each parameter is used, more host-specific declarations should be given near the beginning of the file, and general defaults at the end. .Pp The configuration file has the following format: .Pp Empty lines and lines starting with .Ql # are comments. Otherwise a line is of the format .Dq keyword arguments . Configuration options may be separated by whitespace or optional whitespace and exactly one .Ql = ; the latter format is useful to avoid the need to quote whitespace when specifying configuration options using the .Nm ssh , .Nm scp , and .Nm sftp .Fl o option. Arguments may optionally be enclosed in double quotes .Pq \&" in order to represent arguments containing spaces. .Pp The possible keywords and their meanings are as follows (note that keywords are case-insensitive and arguments are case-sensitive): .Bl -tag -width Ds .It Cm Host Restricts the following declarations (up to the next .Cm Host or .Cm Match keyword) to be only for those hosts that match one of the patterns given after the keyword. If more than one pattern is provided, they should be separated by whitespace. A single .Ql * as a pattern can be used to provide global defaults for all hosts. The host is usually the .Ar hostname argument given on the command line (see the .Cm CanonicalizeHostname option for exceptions.) .Pp A pattern entry may be negated by prefixing it with an exclamation mark .Pq Sq !\& . If a negated entry is matched, then the .Cm Host entry is ignored, regardless of whether any other patterns on the line match. Negated matches are therefore useful to provide exceptions for wildcard matches. .Pp See .Sx PATTERNS for more information on patterns. .It Cm Match Restricts the following declarations (up to the next .Cm Host or .Cm Match keyword) to be used only when the conditions following the .Cm Match keyword are satisfied. Match conditions are specified using one or more critera or the single token .Cm all which always matches. The available criteria keywords are: .Cm canonical , .Cm exec , .Cm host , .Cm originalhost , .Cm user , and .Cm localuser . The .Cm all criteria must appear alone or immediately after .Cm canonical . Other criteria may be combined arbitrarily. All criteria but .Cm all and .Cm canonical require an argument. Criteria may be negated by prepending an exclamation mark .Pq Sq !\& . .Pp The .Cm canonical keyword matches only when the configuration file is being re-parsed after hostname canonicalization (see the .Cm CanonicalizeHostname option.) This may be useful to specify conditions that work with canonical host names only. The .Cm exec keyword executes the specified command under the user's shell. If the command returns a zero exit status then the condition is considered true. Commands containing whitespace characters must be quoted. The following character sequences in the command will be expanded prior to execution: .Ql %L will be substituted by the first component of the local host name, .Ql %l will be substituted by the local host name (including any domain name), .Ql %h will be substituted by the target host name, .Ql %n will be substituted by the original target host name specified on the command-line, .Ql %p the destination port, .Ql %r by the remote login username, and .Ql %u by the username of the user running .Xr ssh 1 . .Pp The other keywords' criteria must be single entries or comma-separated lists and may use the wildcard and negation operators described in the .Sx PATTERNS section. The criteria for the .Cm host keyword are matched against the target hostname, after any substitution by the .Cm Hostname or .Cm CanonicalizeHostname options. The .Cm originalhost keyword matches against the hostname as it was specified on the command-line. The .Cm user keyword matches against the target username on the remote host. The .Cm localuser keyword matches against the name of the local user running .Xr ssh 1 (this keyword may be useful in system-wide .Nm files). .It Cm AddressFamily Specifies which address family to use when connecting. Valid arguments are .Dq any , .Dq inet (use IPv4 only), or .Dq inet6 (use IPv6 only). .It Cm BatchMode If set to .Dq yes , passphrase/password querying will be disabled. This option is useful in scripts and other batch jobs where no user is present to supply the password. The argument must be .Dq yes or .Dq no . The default is .Dq no . .It Cm BindAddress Use the specified address on the local machine as the source address of the connection. Only useful on systems with more than one address. Note that this option does not work if .Cm UsePrivilegedPort is set to .Dq yes . .It Cm CanonicalDomains When .Cm CanonicalizeHostname is enabled, this option specifies the list of domain suffixes in which to search for the specified destination host. .It Cm CanonicalizeFallbackLocal Specifies whether to fail with an error when hostname canonicalization fails. The default, .Dq yes , will attempt to look up the unqualified hostname using the system resolver's search rules. A value of .Dq no will cause .Xr ssh 1 to fail instantly if .Cm CanonicalizeHostname is enabled and the target hostname cannot be found in any of the domains specified by .Cm CanonicalDomains . .It Cm CanonicalizeHostname Controls whether explicit hostname canonicalization is performed. The default, .Dq no , is not to perform any name rewriting and let the system resolver handle all hostname lookups. If set to .Dq yes then, for connections that do not use a .Cm ProxyCommand , .Xr ssh 1 will attempt to canonicalize the hostname specified on the command line using the .Cm CanonicalDomains suffixes and .Cm CanonicalizePermittedCNAMEs rules. If .Cm CanonicalizeHostname is set to .Dq always , then canonicalization is applied to proxied connections too. .Pp If this option is enabled, then the configuration files are processed again using the new target name to pick up any new configuration in matching .Cm Host and .Cm Match stanzas. .It Cm CanonicalizeMaxDots Specifies the maximum number of dot characters in a hostname before canonicalization is disabled. The default, .Dq 1 , allows a single dot (i.e. hostname.subdomain). .It Cm CanonicalizePermittedCNAMEs Specifies rules to determine whether CNAMEs should be followed when canonicalizing hostnames. The rules consist of one or more arguments of .Ar source_domain_list : Ns Ar target_domain_list , where .Ar source_domain_list is a pattern-list of domains that may follow CNAMEs in canonicalization, and .Ar target_domain_list is a pattern-list of domains that they may resolve to. .Pp For example, .Dq *.a.example.com:*.b.example.com,*.c.example.com will allow hostnames matching .Dq *.a.example.com to be canonicalized to names in the .Dq *.b.example.com or .Dq *.c.example.com domains. .It Cm ChallengeResponseAuthentication Specifies whether to use challenge-response authentication. The argument to this keyword must be .Dq yes or .Dq no . The default is .Dq yes . .It Cm CheckHostIP If this flag is set to .Dq yes , .Xr ssh 1 will additionally check the host IP address in the .Pa known_hosts file. This allows ssh to detect if a host key changed due to DNS spoofing and will add addresses of destination hosts to .Pa ~/.ssh/known_hosts in the process, regardless of the setting of .Cm StrictHostKeyChecking . If the option is set to .Dq no , the check will not be executed. The default is .Dq no . .It Cm Cipher Specifies the cipher to use for encrypting the session in protocol version 1. Currently, .Dq blowfish , .Dq 3des , and .Dq des are supported. .Ar des is only supported in the .Xr ssh 1 client for interoperability with legacy protocol 1 implementations that do not support the .Ar 3des cipher. Its use is strongly discouraged due to cryptographic weaknesses. The default is .Dq 3des . .It Cm Ciphers Specifies the ciphers allowed for protocol version 2 in order of preference. Multiple ciphers must be comma-separated. If the specified value begins with a .Sq + character, then the specified ciphers will be appended to the default set instead of replacing them. .Pp The supported ciphers are: .Pp .Bl -item -compact -offset indent .It 3des-cbc .It aes128-cbc .It aes192-cbc .It aes256-cbc .It aes128-ctr .It aes192-ctr .It aes256-ctr .It aes128-gcm@openssh.com .It aes256-gcm@openssh.com .It arcfour .It arcfour128 .It arcfour256 .It blowfish-cbc .It cast128-cbc .It chacha20-poly1305@openssh.com .El .Pp The default is: .Bd -literal -offset indent aes128-ctr,aes192-ctr,aes256-ctr, aes128-gcm@openssh.com,aes256-gcm@openssh.com, chacha20-poly1305@openssh.com, arcfour256,arcfour128, aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc, aes192-cbc,aes256-cbc,arcfour .Ed .Pp The list of available ciphers may also be obtained using the .Fl Q option of .Xr ssh 1 with an argument of .Dq cipher . .It Cm ClearAllForwardings Specifies that all local, remote, and dynamic port forwardings specified in the configuration files or on the command line be cleared. This option is primarily useful when used from the .Xr ssh 1 command line to clear port forwardings set in configuration files, and is automatically set by .Xr scp 1 and .Xr sftp 1 . The argument must be .Dq yes or .Dq no . The default is .Dq no . .It Cm Compression Specifies whether to use compression. The argument must be .Dq yes or .Dq no . The default is .Dq no . .It Cm CompressionLevel Specifies the compression level to use if compression is enabled. The argument must be an integer from 1 (fast) to 9 (slow, best). The default level is 6, which is good for most applications. The meaning of the values is the same as in .Xr gzip 1 . Note that this option applies to protocol version 1 only. .It Cm ConnectionAttempts Specifies the number of tries (one per second) to make before exiting. The argument must be an integer. This may be useful in scripts if the connection sometimes fails. The default is 1. .It Cm ConnectTimeout Specifies the timeout (in seconds) used when connecting to the SSH server, instead of using the default system TCP timeout. This value is used only when the target is down or really unreachable, not when it refuses the connection. .It Cm ControlMaster Enables the sharing of multiple sessions over a single network connection. When set to .Dq yes , .Xr ssh 1 will listen for connections on a control socket specified using the .Cm ControlPath argument. Additional sessions can connect to this socket using the same .Cm ControlPath with .Cm ControlMaster set to .Dq no (the default). These sessions will try to reuse the master instance's network connection rather than initiating new ones, but will fall back to connecting normally if the control socket does not exist, or is not listening. .Pp Setting this to .Dq ask will cause ssh to listen for control connections, but require confirmation using .Xr ssh-askpass 1 . If the .Cm ControlPath cannot be opened, ssh will continue without connecting to a master instance. .Pp X11 and .Xr ssh-agent 1 forwarding is supported over these multiplexed connections, however the display and agent forwarded will be the one belonging to the master connection i.e. it is not possible to forward multiple displays or agents. .Pp Two additional options allow for opportunistic multiplexing: try to use a master connection but fall back to creating a new one if one does not already exist. These options are: .Dq auto and .Dq autoask . The latter requires confirmation like the .Dq ask option. .It Cm ControlPath Specify the path to the control socket used for connection sharing as described in the .Cm ControlMaster section above or the string .Dq none to disable connection sharing. In the path, .Ql %L will be substituted by the first component of the local host name, .Ql %l will be substituted by the local host name (including any domain name), .Ql %h will be substituted by the target host name, .Ql %n will be substituted by the original target host name specified on the command line, .Ql %p the destination port, .Ql %r by the remote login username, .Ql %u by the username of the user running .Xr ssh 1 , and .Ql \&%C by a hash of the concatenation: %l%h%p%r. It is recommended that any .Cm ControlPath used for opportunistic connection sharing include at least %h, %p, and %r (or alternatively %C) and be placed in a directory that is not writable by other users. This ensures that shared connections are uniquely identified. .It Cm ControlPersist When used in conjunction with .Cm ControlMaster , specifies that the master connection should remain open in the background (waiting for future client connections) after the initial client connection has been closed. If set to .Dq no , then the master connection will not be placed into the background, and will close as soon as the initial client connection is closed. If set to .Dq yes or .Dq 0 , then the master connection will remain in the background indefinitely (until killed or closed via a mechanism such as the .Xr ssh 1 .Dq Fl O No exit option). If set to a time in seconds, or a time in any of the formats documented in .Xr sshd_config 5 , then the backgrounded master connection will automatically terminate after it has remained idle (with no client connections) for the specified time. .It Cm DynamicForward Specifies that a TCP port on the local machine be forwarded over the secure channel, and the application protocol is then used to determine where to connect to from the remote machine. .Pp The argument must be .Sm off .Oo Ar bind_address : Oc Ar port . .Sm on IPv6 addresses can be specified by enclosing addresses in square brackets. By default, the local port is bound in accordance with the .Cm GatewayPorts setting. However, an explicit .Ar bind_address may be used to bind the connection to a specific address. The .Ar bind_address of .Dq localhost indicates that the listening port be bound for local use only, while an empty address or .Sq * indicates that the port should be available from all interfaces. .Pp Currently the SOCKS4 and SOCKS5 protocols are supported, and .Xr ssh 1 will act as a SOCKS server. Multiple forwardings may be specified, and additional forwardings can be given on the command line. Only the superuser can forward privileged ports. .It Cm EnableSSHKeysign Setting this option to .Dq yes in the global client configuration file .Pa /etc/ssh/ssh_config enables the use of the helper program .Xr ssh-keysign 8 during .Cm HostbasedAuthentication . The argument must be .Dq yes or .Dq no . The default is .Dq no . This option should be placed in the non-hostspecific section. See .Xr ssh-keysign 8 for more information. .It Cm EscapeChar Sets the escape character (default: .Ql ~ ) . The escape character can also be set on the command line. The argument should be a single character, .Ql ^ followed by a letter, or .Dq none to disable the escape character entirely (making the connection transparent for binary data). .It Cm ExitOnForwardFailure Specifies whether .Xr ssh 1 should terminate the connection if it cannot set up all requested dynamic, tunnel, local, and remote port forwardings. The argument must be .Dq yes or .Dq no . The default is .Dq no . .It Cm FingerprintHash Specifies the hash algorithm used when displaying key fingerprints. Valid options are: .Dq md5 and .Dq sha256 . The default is .Dq sha256 . .It Cm ForwardAgent Specifies whether the connection to the authentication agent (if any) will be forwarded to the remote machine. The argument must be .Dq yes or .Dq no . The default is .Dq no . .Pp Agent forwarding should be enabled with caution. Users with the ability to bypass file permissions on the remote host (for the agent's Unix-domain socket) can access the local agent through the forwarded connection. An attacker cannot obtain key material from the agent, however they can perform operations on the keys that enable them to authenticate using the identities loaded into the agent. .It Cm ForwardX11 Specifies whether X11 connections will be automatically redirected over the secure channel and .Ev DISPLAY set. The argument must be .Dq yes or .Dq no . The default is .Dq no . .Pp X11 forwarding should be enabled with caution. Users with the ability to bypass file permissions on the remote host (for the user's X11 authorization database) can access the local X11 display through the forwarded connection. An attacker may then be able to perform activities such as keystroke monitoring if the .Cm ForwardX11Trusted option is also enabled. .It Cm ForwardX11Timeout Specify a timeout for untrusted X11 forwarding using the format described in the TIME FORMATS section of .Xr sshd_config 5 . X11 connections received by .Xr ssh 1 after this time will be refused. The default is to disable untrusted X11 forwarding after twenty minutes has elapsed. .It Cm ForwardX11Trusted If this option is set to .Dq yes , remote X11 clients will have full access to the original X11 display. .Pp If this option is set to .Dq no , remote X11 clients will be considered untrusted and prevented from stealing or tampering with data belonging to trusted X11 clients. Furthermore, the .Xr xauth 1 token used for the session will be set to expire after 20 minutes. Remote clients will be refused access after this time. .Pp The default is .Dq no . .Pp See the X11 SECURITY extension specification for full details on the restrictions imposed on untrusted clients. .It Cm GatewayPorts Specifies whether remote hosts are allowed to connect to local forwarded ports. By default, .Xr ssh 1 binds local port forwardings to the loopback address. This prevents other remote hosts from connecting to forwarded ports. .Cm GatewayPorts can be used to specify that ssh should bind local port forwardings to the wildcard address, thus allowing remote hosts to connect to forwarded ports. The argument must be .Dq yes or .Dq no . The default is .Dq no . .It Cm GlobalKnownHostsFile Specifies one or more files to use for the global host key database, separated by whitespace. The default is .Pa /etc/ssh/ssh_known_hosts , .Pa /etc/ssh/ssh_known_hosts2 . .It Cm GSSAPIAuthentication Specifies whether user authentication based on GSSAPI is allowed. The default is .Dq no . Note that this option applies to protocol version 2 only. .It Cm GSSAPIDelegateCredentials Forward (delegate) credentials to the server. The default is .Dq no . Note that this option applies to protocol version 2 only. .It Cm HashKnownHosts Indicates that .Xr ssh 1 should hash host names and addresses when they are added to .Pa ~/.ssh/known_hosts . These hashed names may be used normally by .Xr ssh 1 and .Xr sshd 8 , but they do not reveal identifying information should the file's contents be disclosed. The default is .Dq no . Note that existing names and addresses in known hosts files will not be converted automatically, but may be manually hashed using .Xr ssh-keygen 1 . .It Cm HostbasedAuthentication Specifies whether to try rhosts based authentication with public key authentication. The argument must be .Dq yes or .Dq no . The default is .Dq no . This option applies to protocol version 2 only and is similar to .Cm RhostsRSAAuthentication . .It Cm HostbasedKeyTypes Specifies the key types that will be used for hostbased authentication as a comma-separated pattern list. Alternately if the specified value begins with a .Sq + character, then the specified key types will be appended to the default set instead of replacing them. The default for this option is: .Bd -literal -offset 3n ecdsa-sha2-nistp256-cert-v01@openssh.com, ecdsa-sha2-nistp384-cert-v01@openssh.com, ecdsa-sha2-nistp521-cert-v01@openssh.com, ssh-ed25519-cert-v01@openssh.com, ssh-rsa-cert-v01@openssh.com, -ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, -ssh-ed25519,ssh-rsa +ssh-dss-cert-v01@openssh.com, +ecdsa-sha2-nistp256,ecdsa-sha2-nistp384, +ecdsa-sha2-nistp521,ssh-ed25519, +ssh-rsa,ssh-dss .Ed .Pp The .Fl Q option of .Xr ssh 1 may be used to list supported key types. .It Cm HostKeyAlgorithms Specifies the protocol version 2 host key algorithms that the client wants to use in order of preference. Alternately if the specified value begins with a .Sq + character, then the specified key types will be appended to the default set instead of replacing them. The default for this option is: .Bd -literal -offset 3n ecdsa-sha2-nistp256-cert-v01@openssh.com, ecdsa-sha2-nistp384-cert-v01@openssh.com, ecdsa-sha2-nistp521-cert-v01@openssh.com, ssh-ed25519-cert-v01@openssh.com, ssh-rsa-cert-v01@openssh.com, -ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, -ssh-ed25519,ssh-rsa +ssh-dss-cert-v01@openssh.com, +ecdsa-sha2-nistp256,ecdsa-sha2-nistp384, +ecdsa-sha2-nistp521,ssh-ed25519, +ssh-rsa,ssh-dss .Ed .Pp If hostkeys are known for the destination host then this default is modified to prefer their algorithms. .Pp The list of available key types may also be obtained using the .Fl Q option of .Xr ssh 1 with an argument of .Dq key . .It Cm HostKeyAlias Specifies an alias that should be used instead of the real host name when looking up or saving the host key in the host key database files. This option is useful for tunneling SSH connections or for multiple servers running on a single host. .It Cm HostName Specifies the real host name to log into. This can be used to specify nicknames or abbreviations for hosts. If the hostname contains the character sequence .Ql %h , then this will be replaced with the host name specified on the command line (this is useful for manipulating unqualified names). The character sequence .Ql %% will be replaced by a single .Ql % character, which may be used when specifying IPv6 link-local addresses. .Pp The default is the name given on the command line. Numeric IP addresses are also permitted (both on the command line and in .Cm HostName specifications). .It Cm IdentitiesOnly Specifies that .Xr ssh 1 should only use the authentication identity files configured in the .Nm files, even if .Xr ssh-agent 1 or a .Cm PKCS11Provider offers more identities. The argument to this keyword must be .Dq yes or .Dq no . This option is intended for situations where ssh-agent offers many different identities. The default is .Dq no . .It Cm IdentityFile Specifies a file from which the user's DSA, ECDSA, Ed25519 or RSA authentication identity is read. The default is .Pa ~/.ssh/identity for protocol version 1, and .Pa ~/.ssh/id_dsa , .Pa ~/.ssh/id_ecdsa , .Pa ~/.ssh/id_ed25519 and .Pa ~/.ssh/id_rsa for protocol version 2. Additionally, any identities represented by the authentication agent will be used for authentication unless .Cm IdentitiesOnly is set. .Xr ssh 1 will try to load certificate information from the filename obtained by appending .Pa -cert.pub to the path of a specified .Cm IdentityFile . .Pp The file name may use the tilde syntax to refer to a user's home directory or one of the following escape characters: .Ql %d (local user's home directory), .Ql %u (local user name), .Ql %l (local host name), .Ql %h (remote host name) or .Ql %r (remote user name). .Pp It is possible to have multiple identity files specified in configuration files; all these identities will be tried in sequence. Multiple .Cm IdentityFile directives will add to the list of identities tried (this behaviour differs from that of other configuration directives). .Pp .Cm IdentityFile may be used in conjunction with .Cm IdentitiesOnly to select which identities in an agent are offered during authentication. .It Cm IgnoreUnknown Specifies a pattern-list of unknown options to be ignored if they are encountered in configuration parsing. This may be used to suppress errors if .Nm contains options that are unrecognised by .Xr ssh 1 . It is recommended that .Cm IgnoreUnknown be listed early in the configuration file as it will not be applied to unknown options that appear before it. .It Cm IPQoS Specifies the IPv4 type-of-service or DSCP class for connections. Accepted values are .Dq af11 , .Dq af12 , .Dq af13 , .Dq af21 , .Dq af22 , .Dq af23 , .Dq af31 , .Dq af32 , .Dq af33 , .Dq af41 , .Dq af42 , .Dq af43 , .Dq cs0 , .Dq cs1 , .Dq cs2 , .Dq cs3 , .Dq cs4 , .Dq cs5 , .Dq cs6 , .Dq cs7 , .Dq ef , .Dq lowdelay , .Dq throughput , .Dq reliability , or a numeric value. This option may take one or two arguments, separated by whitespace. If one argument is specified, it is used as the packet class unconditionally. If two values are specified, the first is automatically selected for interactive sessions and the second for non-interactive sessions. The default is .Dq lowdelay for interactive sessions and .Dq throughput for non-interactive sessions. .It Cm KbdInteractiveAuthentication Specifies whether to use keyboard-interactive authentication. The argument to this keyword must be .Dq yes or .Dq no . The default is .Dq yes . .It Cm KbdInteractiveDevices Specifies the list of methods to use in keyboard-interactive authentication. Multiple method names must be comma-separated. The default is to use the server specified list. The methods available vary depending on what the server supports. For an OpenSSH server, it may be zero or more of: .Dq bsdauth , .Dq pam , and .Dq skey . .It Cm KexAlgorithms Specifies the available KEX (Key Exchange) algorithms. Multiple algorithms must be comma-separated. Alternately if the specified value begins with a .Sq + character, then the specified methods will be appended to the default set instead of replacing them. The default is: .Bd -literal -offset indent curve25519-sha256@libssh.org, ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521, diffie-hellman-group-exchange-sha256, diffie-hellman-group-exchange-sha1, diffie-hellman-group14-sha1 .Ed .Pp The list of available key exchange algorithms may also be obtained using the .Fl Q option of .Xr ssh 1 with an argument of .Dq kex . .It Cm LocalCommand Specifies a command to execute on the local machine after successfully connecting to the server. The command string extends to the end of the line, and is executed with the user's shell. The following escape character substitutions will be performed: .Ql %d (local user's home directory), .Ql %h (remote host name), .Ql %l (local host name), .Ql %n (host name as provided on the command line), .Ql %p (remote port), .Ql %r (remote user name) or .Ql %u (local user name) or .Ql \&%C by a hash of the concatenation: %l%h%p%r. .Pp The command is run synchronously and does not have access to the session of the .Xr ssh 1 that spawned it. It should not be used for interactive commands. .Pp This directive is ignored unless .Cm PermitLocalCommand has been enabled. .It Cm LocalForward Specifies that a TCP port on the local machine be forwarded over the secure channel to the specified host and port from the remote machine. The first argument must be .Sm off .Oo Ar bind_address : Oc Ar port .Sm on and the second argument must be .Ar host : Ns Ar hostport . IPv6 addresses can be specified by enclosing addresses in square brackets. Multiple forwardings may be specified, and additional forwardings can be given on the command line. Only the superuser can forward privileged ports. By default, the local port is bound in accordance with the .Cm GatewayPorts setting. However, an explicit .Ar bind_address may be used to bind the connection to a specific address. The .Ar bind_address of .Dq localhost indicates that the listening port be bound for local use only, while an empty address or .Sq * indicates that the port should be available from all interfaces. .It Cm LogLevel Gives the verbosity level that is used when logging messages from .Xr ssh 1 . The possible values are: QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. The default is INFO. DEBUG and DEBUG1 are equivalent. DEBUG2 and DEBUG3 each specify higher levels of verbose output. .It Cm MACs Specifies the MAC (message authentication code) algorithms in order of preference. The MAC algorithm is used in protocol version 2 for data integrity protection. Multiple algorithms must be comma-separated. If the specified value begins with a .Sq + character, then the specified algorithms will be appended to the default set instead of replacing them. .Pp The algorithms that contain .Dq -etm calculate the MAC after encryption (encrypt-then-mac). These are considered safer and their use recommended. .Pp The default is: .Bd -literal -offset indent umac-64-etm@openssh.com,umac-128-etm@openssh.com, hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com, umac-64@openssh.com,umac-128@openssh.com, hmac-sha2-256,hmac-sha2-512, hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com, hmac-ripemd160-etm@openssh.com, hmac-sha1-96-etm@openssh.com,hmac-md5-96-etm@openssh.com, hmac-md5,hmac-sha1,hmac-ripemd160, hmac-sha1-96,hmac-md5-96 .Ed .Pp The list of available MAC algorithms may also be obtained using the .Fl Q option of .Xr ssh 1 with an argument of .Dq mac . .It Cm NoHostAuthenticationForLocalhost This option can be used if the home directory is shared across machines. In this case localhost will refer to a different machine on each of the machines and the user will get many warnings about changed host keys. However, this option disables host authentication for localhost. The argument to this keyword must be .Dq yes or .Dq no . The default is to check the host key for localhost. .It Cm NumberOfPasswordPrompts Specifies the number of password prompts before giving up. The argument to this keyword must be an integer. The default is 3. .It Cm PasswordAuthentication Specifies whether to use password authentication. The argument to this keyword must be .Dq yes or .Dq no . The default is .Dq yes . .It Cm PermitLocalCommand Allow local command execution via the .Ic LocalCommand option or using the .Ic !\& Ns Ar command escape sequence in .Xr ssh 1 . The argument must be .Dq yes or .Dq no . The default is .Dq no . .It Cm PKCS11Provider Specifies which PKCS#11 provider to use. The argument to this keyword is the PKCS#11 shared library .Xr ssh 1 should use to communicate with a PKCS#11 token providing the user's private RSA key. .It Cm Port Specifies the port number to connect on the remote host. The default is 22. .It Cm PreferredAuthentications Specifies the order in which the client should try protocol 2 authentication methods. This allows a client to prefer one method (e.g.\& .Cm keyboard-interactive ) over another method (e.g.\& .Cm password ) . The default is: .Bd -literal -offset indent gssapi-with-mic,hostbased,publickey, keyboard-interactive,password .Ed .It Cm Protocol Specifies the protocol versions .Xr ssh 1 should support in order of preference. The possible values are .Sq 1 and .Sq 2 . Multiple versions must be comma-separated. When this option is set to .Dq 2,1 .Nm ssh will try version 2 and fall back to version 1 if version 2 is not available. The default is .Sq 2 . .It Cm ProxyCommand Specifies the command to use to connect to the server. The command string extends to the end of the line, and is executed using the user's shell .Ql exec directive to avoid a lingering shell process. .Pp In the command string, any occurrence of .Ql %h will be substituted by the host name to connect, .Ql %p by the port, and .Ql %r by the remote user name. The command can be basically anything, and should read from its standard input and write to its standard output. It should eventually connect an .Xr sshd 8 server running on some machine, or execute .Ic sshd -i somewhere. Host key management will be done using the HostName of the host being connected (defaulting to the name typed by the user). Setting the command to .Dq none disables this option entirely. Note that .Cm CheckHostIP is not available for connects with a proxy command. .Pp This directive is useful in conjunction with .Xr nc 1 and its proxy support. For example, the following directive would connect via an HTTP proxy at 192.0.2.0: .Bd -literal -offset 3n ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p .Ed .It Cm ProxyUseFdpass Specifies that .Cm ProxyCommand will pass a connected file descriptor back to .Xr ssh 1 instead of continuing to execute and pass data. The default is .Dq no . .It Cm PubkeyAcceptedKeyTypes Specifies the key types that will be used for public key authentication as a comma-separated pattern list. Alternately if the specified value begins with a .Sq + character, then the key types after it will be appended to the default instead of replacing it. The default for this option is: .Bd -literal -offset 3n ecdsa-sha2-nistp256-cert-v01@openssh.com, ecdsa-sha2-nistp384-cert-v01@openssh.com, ecdsa-sha2-nistp521-cert-v01@openssh.com, ssh-ed25519-cert-v01@openssh.com, ssh-rsa-cert-v01@openssh.com, -ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, -ssh-ed25519,ssh-rsa +ssh-dss-cert-v01@openssh.com, +ecdsa-sha2-nistp256,ecdsa-sha2-nistp384, +ecdsa-sha2-nistp521,ssh-ed25519, +ssh-rsa,ssh-dss .Ed .Pp The .Fl Q option of .Xr ssh 1 may be used to list supported key types. .It Cm PubkeyAuthentication Specifies whether to try public key authentication. The argument to this keyword must be .Dq yes or .Dq no . The default is .Dq yes . This option applies to protocol version 2 only. .It Cm RekeyLimit Specifies the maximum amount of data that may be transmitted before the session key is renegotiated, optionally followed a maximum amount of time that may pass before the session key is renegotiated. The first argument is specified in bytes and may have a suffix of .Sq K , .Sq M , or .Sq G to indicate Kilobytes, Megabytes, or Gigabytes, respectively. The default is between .Sq 1G and .Sq 4G , depending on the cipher. The optional second value is specified in seconds and may use any of the units documented in the TIME FORMATS section of .Xr sshd_config 5 . The default value for .Cm RekeyLimit is .Dq default none , which means that rekeying is performed after the cipher's default amount of data has been sent or received and no time based rekeying is done. This option applies to protocol version 2 only. .It Cm RemoteForward Specifies that a TCP port on the remote machine be forwarded over the secure channel to the specified host and port from the local machine. The first argument must be .Sm off .Oo Ar bind_address : Oc Ar port .Sm on and the second argument must be .Ar host : Ns Ar hostport . IPv6 addresses can be specified by enclosing addresses in square brackets. Multiple forwardings may be specified, and additional forwardings can be given on the command line. Privileged ports can be forwarded only when logging in as root on the remote machine. .Pp If the .Ar port argument is .Ql 0 , the listen port will be dynamically allocated on the server and reported to the client at run time. .Pp If the .Ar bind_address is not specified, the default is to only bind to loopback addresses. If the .Ar bind_address is .Ql * or an empty string, then the forwarding is requested to listen on all interfaces. Specifying a remote .Ar bind_address will only succeed if the server's .Cm GatewayPorts option is enabled (see .Xr sshd_config 5 ) . .It Cm RequestTTY Specifies whether to request a pseudo-tty for the session. The argument may be one of: .Dq no (never request a TTY), .Dq yes (always request a TTY when standard input is a TTY), .Dq force (always request a TTY) or .Dq auto (request a TTY when opening a login session). This option mirrors the .Fl t and .Fl T flags for .Xr ssh 1 . .It Cm RevokedHostKeys Specifies revoked host public keys. Keys listed in this file will be refused for host authentication. Note that if this file does not exist or is not readable, then host authentication will be refused for all hosts. Keys may be specified as a text file, listing one public key per line, or as an OpenSSH Key Revocation List (KRL) as generated by .Xr ssh-keygen 1 . For more information on KRLs, see the KEY REVOCATION LISTS section in .Xr ssh-keygen 1 . .It Cm RhostsRSAAuthentication Specifies whether to try rhosts based authentication with RSA host authentication. The argument must be .Dq yes or .Dq no . The default is .Dq no . This option applies to protocol version 1 only and requires .Xr ssh 1 to be setuid root. .It Cm RSAAuthentication Specifies whether to try RSA authentication. The argument to this keyword must be .Dq yes or .Dq no . RSA authentication will only be attempted if the identity file exists, or an authentication agent is running. The default is .Dq yes . Note that this option applies to protocol version 1 only. .It Cm SendEnv Specifies what variables from the local .Xr environ 7 should be sent to the server. Note that environment passing is only supported for protocol 2. The server must also support it, and the server must be configured to accept these environment variables. Note that the .Ev TERM environment variable is always sent whenever a pseudo-terminal is requested as it is required by the protocol. Refer to .Cm AcceptEnv in .Xr sshd_config 5 for how to configure the server. Variables are specified by name, which may contain wildcard characters. Multiple environment variables may be separated by whitespace or spread across multiple .Cm SendEnv directives. The default is not to send any environment variables. .Pp See .Sx PATTERNS for more information on patterns. .It Cm ServerAliveCountMax Sets the number of server alive messages (see below) which may be sent without .Xr ssh 1 receiving any messages back from the server. If this threshold is reached while server alive messages are being sent, ssh will disconnect from the server, terminating the session. It is important to note that the use of server alive messages is very different from .Cm TCPKeepAlive (below). The server alive messages are sent through the encrypted channel and therefore will not be spoofable. The TCP keepalive option enabled by .Cm TCPKeepAlive is spoofable. The server alive mechanism is valuable when the client or server depend on knowing when a connection has become inactive. .Pp The default value is 3. If, for example, .Cm ServerAliveInterval (see below) is set to 15 and .Cm ServerAliveCountMax is left at the default, if the server becomes unresponsive, ssh will disconnect after approximately 45 seconds. This option applies to protocol version 2 only. .It Cm ServerAliveInterval Sets a timeout interval in seconds after which if no data has been received from the server, .Xr ssh 1 will send a message through the encrypted channel to request a response from the server. The default is 0, indicating that these messages will not be sent to the server. This option applies to protocol version 2 only. .It Cm StreamLocalBindMask Sets the octal file creation mode mask .Pq umask used when creating a Unix-domain socket file for local or remote port forwarding. This option is only used for port forwarding to a Unix-domain socket file. .Pp The default value is 0177, which creates a Unix-domain socket file that is readable and writable only by the owner. Note that not all operating systems honor the file mode on Unix-domain socket files. .It Cm StreamLocalBindUnlink Specifies whether to remove an existing Unix-domain socket file for local or remote port forwarding before creating a new one. If the socket file already exists and .Cm StreamLocalBindUnlink is not enabled, .Nm ssh will be unable to forward the port to the Unix-domain socket file. This option is only used for port forwarding to a Unix-domain socket file. .Pp The argument must be .Dq yes or .Dq no . The default is .Dq no . .It Cm StrictHostKeyChecking If this flag is set to .Dq yes , .Xr ssh 1 will never automatically add host keys to the .Pa ~/.ssh/known_hosts file, and refuses to connect to hosts whose host key has changed. This provides maximum protection against trojan horse attacks, though it can be annoying when the .Pa /etc/ssh/ssh_known_hosts file is poorly maintained or when connections to new hosts are frequently made. This option forces the user to manually add all new hosts. If this flag is set to .Dq no , ssh will automatically add new host keys to the user known hosts files. If this flag is set to .Dq ask , new host keys will be added to the user known host files only after the user has confirmed that is what they really want to do, and ssh will refuse to connect to hosts whose host key has changed. The host keys of known hosts will be verified automatically in all cases. The argument must be .Dq yes , .Dq no , or .Dq ask . The default is .Dq ask . .It Cm TCPKeepAlive Specifies whether the system should send TCP keepalive messages to the other side. If they are sent, death of the connection or crash of one of the machines will be properly noticed. However, this means that connections will die if the route is down temporarily, and some people find it annoying. .Pp The default is .Dq yes (to send TCP keepalive messages), and the client will notice if the network goes down or the remote host dies. This is important in scripts, and many users want it too. .Pp To disable TCP keepalive messages, the value should be set to .Dq no . .It Cm Tunnel Request .Xr tun 4 device forwarding between the client and the server. The argument must be .Dq yes , .Dq point-to-point (layer 3), .Dq ethernet (layer 2), or .Dq no . Specifying .Dq yes requests the default tunnel mode, which is .Dq point-to-point . The default is .Dq no . .It Cm TunnelDevice Specifies the .Xr tun 4 devices to open on the client .Pq Ar local_tun and the server .Pq Ar remote_tun . .Pp The argument must be .Sm off .Ar local_tun Op : Ar remote_tun . .Sm on The devices may be specified by numerical ID or the keyword .Dq any , which uses the next available tunnel device. If .Ar remote_tun is not specified, it defaults to .Dq any . The default is .Dq any:any . .It Cm UpdateHostKeys Specifies whether .Xr ssh 1 should accept notifications of additional hostkeys from the server sent after authentication has completed and add them to .Cm UserKnownHostsFile . The argument must be .Dq yes , .Dq no (the default) or .Dq ask . Enabling this option allows learning alternate hostkeys for a server and supports graceful key rotation by allowing a server to send replacement public keys before old ones are removed. Additional hostkeys are only accepted if the key used to authenticate the host was already trusted or explicity accepted by the user. If .Cm UpdateHostKeys is set to .Dq ask , then the user is asked to confirm the modifications to the known_hosts file. Confirmation is currently incompatible with .Cm ControlPersist , and will be disabled if it is enabled. .Pp Presently, only .Xr sshd 8 from OpenSSH 6.8 and greater support the .Dq hostkeys@openssh.com protocol extension used to inform the client of all the server's hostkeys. .It Cm UsePrivilegedPort Specifies whether to use a privileged port for outgoing connections. The argument must be .Dq yes or .Dq no . The default is .Dq no . If set to .Dq yes , .Xr ssh 1 must be setuid root. Note that this option must be set to .Dq yes for .Cm RhostsRSAAuthentication with older servers. .It Cm User Specifies the user to log in as. This can be useful when a different user name is used on different machines. This saves the trouble of having to remember to give the user name on the command line. .It Cm UserKnownHostsFile Specifies one or more files to use for the user host key database, separated by whitespace. The default is .Pa ~/.ssh/known_hosts , .Pa ~/.ssh/known_hosts2 . .It Cm VerifyHostKeyDNS Specifies whether to verify the remote key using DNS and SSHFP resource records. If this option is set to .Dq yes , the client will implicitly trust keys that match a secure fingerprint from DNS. Insecure fingerprints will be handled as if this option was set to .Dq ask . If this option is set to .Dq ask , information on fingerprint match will be displayed, but the user will still need to confirm new host keys according to the .Cm StrictHostKeyChecking option. The argument must be .Dq yes , .Dq no , or .Dq ask . The default is .Dq yes if compiled with LDNS and .Dq no otherwise. Note that this option applies to protocol version 2 only. .Pp See also VERIFYING HOST KEYS in .Xr ssh 1 . .It Cm VersionAddendum Specifies a string to append to the regular version string to identify OS- or site-specific modifications. The default is .Dq FreeBSD-20160119 . The value .Dq none may be used to disable this. .It Cm VisualHostKey If this flag is set to .Dq yes , an ASCII art representation of the remote host key fingerprint is printed in addition to the fingerprint string at login and for unknown host keys. If this flag is set to .Dq no , no fingerprint strings are printed at login and only the fingerprint string will be printed for unknown host keys. The default is .Dq no . .It Cm XAuthLocation Specifies the full pathname of the .Xr xauth 1 program. The default is .Pa /usr/local/bin/xauth . .El .Sh PATTERNS A .Em pattern consists of zero or more non-whitespace characters, .Sq * (a wildcard that matches zero or more characters), or .Sq ?\& (a wildcard that matches exactly one character). For example, to specify a set of declarations for any host in the .Dq .co.uk set of domains, the following pattern could be used: .Pp .Dl Host *.co.uk .Pp The following pattern would match any host in the 192.168.0.[0-9] network range: .Pp .Dl Host 192.168.0.? .Pp A .Em pattern-list is a comma-separated list of patterns. Patterns within pattern-lists may be negated by preceding them with an exclamation mark .Pq Sq !\& . For example, to allow a key to be used from anywhere within an organization except from the .Dq dialup pool, the following entry (in authorized_keys) could be used: .Pp .Dl from=\&"!*.dialup.example.com,*.example.com\&" .Sh FILES .Bl -tag -width Ds .It Pa ~/.ssh/config This is the per-user configuration file. The format of this file is described above. This file is used by the SSH client. Because of the potential for abuse, this file must have strict permissions: read/write for the user, and not accessible by others. .It Pa /etc/ssh/ssh_config Systemwide configuration file. This file provides defaults for those values that are not specified in the user's configuration file, and for those users who do not have a configuration file. This file must be world-readable. .El .Sh SEE ALSO .Xr ssh 1 .Sh AUTHORS OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re-added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. Index: head/crypto/openssh/sshd_config.5 =================================================================== --- head/crypto/openssh/sshd_config.5 (revision 294494) +++ head/crypto/openssh/sshd_config.5 (revision 294495) @@ -1,1750 +1,1756 @@ .\" .\" Author: Tatu Ylonen .\" Copyright (c) 1995 Tatu Ylonen , Espoo, Finland .\" All rights reserved .\" .\" As far as I am concerned, the code I have written for this software .\" can be used freely for any purpose. Any derived versions of this .\" software must be clearly marked as such, and if the derived work is .\" incompatible with the protocol description in the RFC file, it must be .\" called by a name other than "ssh" or "Secure Shell". .\" .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved. .\" Copyright (c) 1999 Aaron Campbell. All rights reserved. .\" Copyright (c) 1999 Theo de Raadt. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" .\" $OpenBSD: sshd_config.5,v 1.210 2015/08/06 14:53:21 deraadt Exp $ .\" $FreeBSD$ .Dd $Mdocdate: August 6 2015 $ .Dt SSHD_CONFIG 5 .Os .Sh NAME .Nm sshd_config .Nd OpenSSH SSH daemon configuration file .Sh SYNOPSIS .Nm /etc/ssh/sshd_config .Sh DESCRIPTION .Xr sshd 8 reads configuration data from .Pa /etc/ssh/sshd_config (or the file specified with .Fl f on the command line). The file contains keyword-argument pairs, one per line. Lines starting with .Ql # and empty lines are interpreted as comments. Arguments may optionally be enclosed in double quotes .Pq \&" in order to represent arguments containing spaces. .Pp The possible keywords and their meanings are as follows (note that keywords are case-insensitive and arguments are case-sensitive): .Bl -tag -width Ds .It Cm AcceptEnv Specifies what environment variables sent by the client will be copied into the session's .Xr environ 7 . See .Cm SendEnv in .Xr ssh_config 5 for how to configure the client. Note that environment passing is only supported for protocol 2, and that the .Ev TERM environment variable is always sent whenever the client requests a pseudo-terminal as it is required by the protocol. Variables are specified by name, which may contain the wildcard characters .Ql * and .Ql \&? . Multiple environment variables may be separated by whitespace or spread across multiple .Cm AcceptEnv directives. Be warned that some environment variables could be used to bypass restricted user environments. For this reason, care should be taken in the use of this directive. The default is not to accept any environment variables. .It Cm AddressFamily Specifies which address family should be used by .Xr sshd 8 . Valid arguments are .Dq any , .Dq inet (use IPv4 only), or .Dq inet6 (use IPv6 only). The default is .Dq any . .It Cm AllowAgentForwarding Specifies whether .Xr ssh-agent 1 forwarding is permitted. The default is .Dq yes . Note that disabling agent forwarding does not improve security unless users are also denied shell access, as they can always install their own forwarders. .It Cm AllowGroups This keyword can be followed by a list of group name patterns, separated by spaces. If specified, login is allowed only for users whose primary group or supplementary group list matches one of the patterns. Only group names are valid; a numerical group ID is not recognized. By default, login is allowed for all groups. The allow/deny directives are processed in the following order: .Cm DenyUsers , .Cm AllowUsers , .Cm DenyGroups , and finally .Cm AllowGroups . .Pp See PATTERNS in .Xr ssh_config 5 for more information on patterns. .It Cm AllowTcpForwarding Specifies whether TCP forwarding is permitted. The available options are .Dq yes or .Dq all to allow TCP forwarding, .Dq no to prevent all TCP forwarding, .Dq local to allow local (from the perspective of .Xr ssh 1 ) forwarding only or .Dq remote to allow remote forwarding only. The default is .Dq yes . Note that disabling TCP forwarding does not improve security unless users are also denied shell access, as they can always install their own forwarders. .It Cm AllowStreamLocalForwarding Specifies whether StreamLocal (Unix-domain socket) forwarding is permitted. The available options are .Dq yes or .Dq all to allow StreamLocal forwarding, .Dq no to prevent all StreamLocal forwarding, .Dq local to allow local (from the perspective of .Xr ssh 1 ) forwarding only or .Dq remote to allow remote forwarding only. The default is .Dq yes . Note that disabling StreamLocal forwarding does not improve security unless users are also denied shell access, as they can always install their own forwarders. .It Cm AllowUsers This keyword can be followed by a list of user name patterns, separated by spaces. If specified, login is allowed only for user names that match one of the patterns. Only user names are valid; a numerical user ID is not recognized. By default, login is allowed for all users. If the pattern takes the form USER@HOST then USER and HOST are separately checked, restricting logins to particular users from particular hosts. The allow/deny directives are processed in the following order: .Cm DenyUsers , .Cm AllowUsers , .Cm DenyGroups , and finally .Cm AllowGroups . .Pp See PATTERNS in .Xr ssh_config 5 for more information on patterns. .It Cm AuthenticationMethods Specifies the authentication methods that must be successfully completed for a user to be granted access. This option must be followed by one or more comma-separated lists of authentication method names. Successful authentication requires completion of every method in at least one of these lists. .Pp For example, an argument of .Dq publickey,password publickey,keyboard-interactive would require the user to complete public key authentication, followed by either password or keyboard interactive authentication. Only methods that are next in one or more lists are offered at each stage, so for this example, it would not be possible to attempt password or keyboard-interactive authentication before public key. .Pp For keyboard interactive authentication it is also possible to restrict authentication to a specific device by appending a colon followed by the device identifier .Dq bsdauth , .Dq pam , or .Dq skey , depending on the server configuration. For example, .Dq keyboard-interactive:bsdauth would restrict keyboard interactive authentication to the .Dq bsdauth device. .Pp If the .Dq publickey method is listed more than once, .Xr sshd 8 verifies that keys that have been used successfully are not reused for subsequent authentications. For example, an .Cm AuthenticationMethods of .Dq publickey,publickey will require successful authentication using two different public keys. .Pp This option is only available for SSH protocol 2 and will yield a fatal error if enabled if protocol 1 is also enabled. Note that each authentication method listed should also be explicitly enabled in the configuration. The default is not to require multiple authentication; successful completion of a single authentication method is sufficient. .It Cm AuthorizedKeysCommand Specifies a program to be used to look up the user's public keys. The program must be owned by root, not writable by group or others and specified by an absolute path. .Pp Arguments to .Cm AuthorizedKeysCommand may be provided using the following tokens, which will be expanded at runtime: %% is replaced by a literal '%', %u is replaced by the username being authenticated, %h is replaced by the home directory of the user being authenticated, %t is replaced with the key type offered for authentication, %f is replaced with the fingerprint of the key, and %k is replaced with the key being offered for authentication. If no arguments are specified then the username of the target user will be supplied. .Pp The program should produce on standard output zero or more lines of authorized_keys output (see AUTHORIZED_KEYS in .Xr sshd 8 ) . If a key supplied by AuthorizedKeysCommand does not successfully authenticate and authorize the user then public key authentication continues using the usual .Cm AuthorizedKeysFile files. By default, no AuthorizedKeysCommand is run. .It Cm AuthorizedKeysCommandUser Specifies the user under whose account the AuthorizedKeysCommand is run. It is recommended to use a dedicated user that has no other role on the host than running authorized keys commands. If .Cm AuthorizedKeysCommand is specified but .Cm AuthorizedKeysCommandUser is not, then .Xr sshd 8 will refuse to start. .It Cm AuthorizedKeysFile Specifies the file that contains the public keys that can be used for user authentication. The format is described in the AUTHORIZED_KEYS FILE FORMAT section of .Xr sshd 8 . .Cm AuthorizedKeysFile may contain tokens of the form %T which are substituted during connection setup. The following tokens are defined: %% is replaced by a literal '%', %h is replaced by the home directory of the user being authenticated, and %u is replaced by the username of that user. After expansion, .Cm AuthorizedKeysFile is taken to be an absolute path or one relative to the user's home directory. Multiple files may be listed, separated by whitespace. The default is .Dq .ssh/authorized_keys .ssh/authorized_keys2 . .It Cm AuthorizedPrincipalsCommand Specifies a program to be used to generate the list of allowed certificate principals as per .Cm AuthorizedPrincipalsFile . The program must be owned by root, not writable by group or others and specified by an absolute path. .Pp Arguments to .Cm AuthorizedPrincipalsCommand may be provided using the following tokens, which will be expanded at runtime: %% is replaced by a literal '%', %u is replaced by the username being authenticated and %h is replaced by the home directory of the user being authenticated. .Pp The program should produce on standard output zero or more lines of .Cm AuthorizedPrincipalsFile output. If either .Cm AuthorizedPrincipalsCommand or .Cm AuthorizedPrincipalsFile is specified, then certificates offered by the client for authentication must contain a principal that is listed. By default, no AuthorizedPrincipalsCommand is run. .It Cm AuthorizedPrincipalsCommandUser Specifies the user under whose account the AuthorizedPrincipalsCommand is run. It is recommended to use a dedicated user that has no other role on the host than running authorized principals commands. If .Cm AuthorizedPrincipalsCommand is specified but .Cm AuthorizedPrincipalsCommandUser is not, then .Xr sshd 8 will refuse to start. .It Cm AuthorizedPrincipalsFile Specifies a file that lists principal names that are accepted for certificate authentication. When using certificates signed by a key listed in .Cm TrustedUserCAKeys , this file lists names, one of which must appear in the certificate for it to be accepted for authentication. Names are listed one per line preceded by key options (as described in AUTHORIZED_KEYS FILE FORMAT in .Xr sshd 8 ) . Empty lines and comments starting with .Ql # are ignored. .Pp .Cm AuthorizedPrincipalsFile may contain tokens of the form %T which are substituted during connection setup. The following tokens are defined: %% is replaced by a literal '%', %h is replaced by the home directory of the user being authenticated, and %u is replaced by the username of that user. After expansion, .Cm AuthorizedPrincipalsFile is taken to be an absolute path or one relative to the user's home directory. .Pp The default is .Dq none , i.e. not to use a principals file \(en in this case, the username of the user must appear in a certificate's principals list for it to be accepted. Note that .Cm AuthorizedPrincipalsFile is only used when authentication proceeds using a CA listed in .Cm TrustedUserCAKeys and is not consulted for certification authorities trusted via .Pa ~/.ssh/authorized_keys , though the .Cm principals= key option offers a similar facility (see .Xr sshd 8 for details). .It Cm Banner The contents of the specified file are sent to the remote user before authentication is allowed. If the argument is .Dq none then no banner is displayed. This option is only available for protocol version 2. By default, no banner is displayed. .It Cm ChallengeResponseAuthentication Specifies whether challenge-response authentication is allowed (e.g. via PAM or through authentication styles supported in .Xr login.conf 5 ) The default is .Dq yes . .It Cm ChrootDirectory Specifies the pathname of a directory to .Xr chroot 2 to after authentication. At session startup .Xr sshd 8 checks that all components of the pathname are root-owned directories which are not writable by any other user or group. After the chroot, .Xr sshd 8 changes the working directory to the user's home directory. .Pp The pathname may contain the following tokens that are expanded at runtime once the connecting user has been authenticated: %% is replaced by a literal '%', %h is replaced by the home directory of the user being authenticated, and %u is replaced by the username of that user. .Pp The .Cm ChrootDirectory must contain the necessary files and directories to support the user's session. For an interactive session this requires at least a shell, typically .Xr sh 1 , and basic .Pa /dev nodes such as .Xr null 4 , .Xr zero 4 , .Xr stdin 4 , .Xr stdout 4 , .Xr stderr 4 , and .Xr tty 4 devices. For file transfer sessions using .Dq sftp , no additional configuration of the environment is necessary if the in-process sftp server is used, though sessions which use logging may require .Pa /dev/log inside the chroot directory on some operating systems (see .Xr sftp-server 8 for details). .Pp For safety, it is very important that the directory hierarchy be prevented from modification by other processes on the system (especially those outside the jail). Misconfiguration can lead to unsafe environments which .Xr sshd 8 cannot detect. .Pp The default is not to .Xr chroot 2 . .It Cm Ciphers Specifies the ciphers allowed for protocol version 2. Multiple ciphers must be comma-separated. If the specified value begins with a .Sq + character, then the specified ciphers will be appended to the default set instead of replacing them. .Pp The supported ciphers are: .Pp .Bl -item -compact -offset indent .It 3des-cbc .It aes128-cbc .It aes192-cbc .It aes256-cbc .It aes128-ctr .It aes192-ctr .It aes256-ctr .It aes128-gcm@openssh.com .It aes256-gcm@openssh.com .It arcfour .It arcfour128 .It arcfour256 .It blowfish-cbc .It cast128-cbc .It chacha20-poly1305@openssh.com .El .Pp The default is: .Bd -literal -offset indent aes128-ctr,aes192-ctr,aes256-ctr, aes128-gcm@openssh.com,aes256-gcm@openssh.com, chacha20-poly1305@openssh.com .Ed .Pp The list of available ciphers may also be obtained using the .Fl Q option of .Xr ssh 1 with an argument of .Dq cipher . .It Cm ClientAliveCountMax Sets the number of client alive messages (see below) which may be sent without .Xr sshd 8 receiving any messages back from the client. If this threshold is reached while client alive messages are being sent, sshd will disconnect the client, terminating the session. It is important to note that the use of client alive messages is very different from .Cm TCPKeepAlive (below). The client alive messages are sent through the encrypted channel and therefore will not be spoofable. The TCP keepalive option enabled by .Cm TCPKeepAlive is spoofable. The client alive mechanism is valuable when the client or server depend on knowing when a connection has become inactive. .Pp The default value is 3. If .Cm ClientAliveInterval (see below) is set to 15, and .Cm ClientAliveCountMax is left at the default, unresponsive SSH clients will be disconnected after approximately 45 seconds. This option applies to protocol version 2 only. .It Cm ClientAliveInterval Sets a timeout interval in seconds after which if no data has been received from the client, .Xr sshd 8 will send a message through the encrypted channel to request a response from the client. The default is 0, indicating that these messages will not be sent to the client. This option applies to protocol version 2 only. .It Cm Compression Specifies whether compression is allowed, or delayed until the user has authenticated successfully. The argument must be .Dq yes , .Dq delayed , or .Dq no . The default is .Dq delayed . .It Cm DenyGroups This keyword can be followed by a list of group name patterns, separated by spaces. Login is disallowed for users whose primary group or supplementary group list matches one of the patterns. Only group names are valid; a numerical group ID is not recognized. By default, login is allowed for all groups. The allow/deny directives are processed in the following order: .Cm DenyUsers , .Cm AllowUsers , .Cm DenyGroups , and finally .Cm AllowGroups . .Pp See PATTERNS in .Xr ssh_config 5 for more information on patterns. .It Cm DenyUsers This keyword can be followed by a list of user name patterns, separated by spaces. Login is disallowed for user names that match one of the patterns. Only user names are valid; a numerical user ID is not recognized. By default, login is allowed for all users. If the pattern takes the form USER@HOST then USER and HOST are separately checked, restricting logins to particular users from particular hosts. The allow/deny directives are processed in the following order: .Cm DenyUsers , .Cm AllowUsers , .Cm DenyGroups , and finally .Cm AllowGroups . .Pp See PATTERNS in .Xr ssh_config 5 for more information on patterns. .It Cm FingerprintHash Specifies the hash algorithm used when logging key fingerprints. Valid options are: .Dq md5 and .Dq sha256 . The default is .Dq sha256 . .It Cm ForceCommand Forces the execution of the command specified by .Cm ForceCommand , ignoring any command supplied by the client and .Pa ~/.ssh/rc if present. The command is invoked by using the user's login shell with the -c option. This applies to shell, command, or subsystem execution. It is most useful inside a .Cm Match block. The command originally supplied by the client is available in the .Ev SSH_ORIGINAL_COMMAND environment variable. Specifying a command of .Dq internal-sftp will force the use of an in-process sftp server that requires no support files when used with .Cm ChrootDirectory . .It Cm GatewayPorts Specifies whether remote hosts are allowed to connect to ports forwarded for the client. By default, .Xr sshd 8 binds remote port forwardings to the loopback address. This prevents other remote hosts from connecting to forwarded ports. .Cm GatewayPorts can be used to specify that sshd should allow remote port forwardings to bind to non-loopback addresses, thus allowing other hosts to connect. The argument may be .Dq no to force remote port forwardings to be available to the local host only, .Dq yes to force remote port forwardings to bind to the wildcard address, or .Dq clientspecified to allow the client to select the address to which the forwarding is bound. The default is .Dq no . .It Cm GSSAPIAuthentication Specifies whether user authentication based on GSSAPI is allowed. The default is .Dq no . Note that this option applies to protocol version 2 only. .It Cm GSSAPICleanupCredentials Specifies whether to automatically destroy the user's credentials cache on logout. The default is .Dq yes . Note that this option applies to protocol version 2 only. .It Cm GSSAPIStrictAcceptorCheck Determines whether to be strict about the identity of the GSSAPI acceptor a client authenticates against. If set to .Dq yes then the client must authenticate against the .Pa host service on the current hostname. If set to .Dq no then the client may authenticate against any service key stored in the machine's default store. This facility is provided to assist with operation on multi homed machines. The default is .Dq yes . .It Cm HostbasedAcceptedKeyTypes Specifies the key types that will be accepted for hostbased authentication as a comma-separated pattern list. Alternately if the specified value begins with a .Sq + character, then the specified key types will be appended to the default set instead of replacing them. The default for this option is: .Bd -literal -offset 3n ecdsa-sha2-nistp256-cert-v01@openssh.com, ecdsa-sha2-nistp384-cert-v01@openssh.com, ecdsa-sha2-nistp521-cert-v01@openssh.com, ssh-ed25519-cert-v01@openssh.com, ssh-rsa-cert-v01@openssh.com, -ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, -ssh-ed25519,ssh-rsa +ssh-dss-cert-v01@openssh.com, +ecdsa-sha2-nistp256,ecdsa-sha2-nistp384, +ecdsa-sha2-nistp521,ssh-ed25519, +ssh-rsa,ssh-dss .Ed .Pp The .Fl Q option of .Xr ssh 1 may be used to list supported key types. .It Cm HostbasedAuthentication Specifies whether rhosts or /etc/hosts.equiv authentication together with successful public key client host authentication is allowed (host-based authentication). This option is similar to .Cm RhostsRSAAuthentication and applies to protocol version 2 only. The default is .Dq no . .It Cm HostbasedUsesNameFromPacketOnly Specifies whether or not the server will attempt to perform a reverse name lookup when matching the name in the .Pa ~/.shosts , .Pa ~/.rhosts , and .Pa /etc/hosts.equiv files during .Cm HostbasedAuthentication . A setting of .Dq yes means that .Xr sshd 8 uses the name supplied by the client rather than attempting to resolve the name from the TCP connection itself. The default is .Dq no . .It Cm HostCertificate Specifies a file containing a public host certificate. The certificate's public key must match a private host key already specified by .Cm HostKey . The default behaviour of .Xr sshd 8 is not to load any certificates. .It Cm HostKey Specifies a file containing a private host key used by SSH. The default is .Pa /etc/ssh/ssh_host_key for protocol version 1, and .Pa /etc/ssh/ssh_host_dsa_key , .Pa /etc/ssh/ssh_host_ecdsa_key , .Pa /etc/ssh/ssh_host_ed25519_key and .Pa /etc/ssh/ssh_host_rsa_key for protocol version 2. .Pp Note that .Xr sshd 8 will refuse to use a file if it is group/world-accessible and that the .Cm HostKeyAlgorithms option restricts which of the keys are actually used by .Xr sshd 8 . .Pp It is possible to have multiple host key files. .Dq rsa1 keys are used for version 1 and .Dq dsa , .Dq ecdsa , .Dq ed25519 or .Dq rsa are used for version 2 of the SSH protocol. It is also possible to specify public host key files instead. In this case operations on the private key will be delegated to an .Xr ssh-agent 1 . .It Cm HostKeyAgent Identifies the UNIX-domain socket used to communicate with an agent that has access to the private host keys. If .Dq SSH_AUTH_SOCK is specified, the location of the socket will be read from the .Ev SSH_AUTH_SOCK environment variable. .It Cm HostKeyAlgorithms Specifies the protocol version 2 host key algorithms that the server offers. The default for this option is: .Bd -literal -offset 3n ecdsa-sha2-nistp256-cert-v01@openssh.com, ecdsa-sha2-nistp384-cert-v01@openssh.com, ecdsa-sha2-nistp521-cert-v01@openssh.com, ssh-ed25519-cert-v01@openssh.com, ssh-rsa-cert-v01@openssh.com, -ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, -ssh-ed25519,ssh-rsa +ssh-dss-cert-v01@openssh.com, +ecdsa-sha2-nistp256,ecdsa-sha2-nistp384, +ecdsa-sha2-nistp521,ssh-ed25519, +ssh-rsa,ssh-dss .Ed .Pp The list of available key types may also be obtained using the .Fl Q option of .Xr ssh 1 with an argument of .Dq key . .It Cm IgnoreRhosts Specifies that .Pa .rhosts and .Pa .shosts files will not be used in .Cm RhostsRSAAuthentication or .Cm HostbasedAuthentication . .Pp .Pa /etc/hosts.equiv and .Pa /etc/ssh/shosts.equiv are still used. The default is .Dq yes . .It Cm IgnoreUserKnownHosts Specifies whether .Xr sshd 8 should ignore the user's .Pa ~/.ssh/known_hosts during .Cm RhostsRSAAuthentication or .Cm HostbasedAuthentication . The default is .Dq no . .It Cm IPQoS Specifies the IPv4 type-of-service or DSCP class for the connection. Accepted values are .Dq af11 , .Dq af12 , .Dq af13 , .Dq af21 , .Dq af22 , .Dq af23 , .Dq af31 , .Dq af32 , .Dq af33 , .Dq af41 , .Dq af42 , .Dq af43 , .Dq cs0 , .Dq cs1 , .Dq cs2 , .Dq cs3 , .Dq cs4 , .Dq cs5 , .Dq cs6 , .Dq cs7 , .Dq ef , .Dq lowdelay , .Dq throughput , .Dq reliability , or a numeric value. This option may take one or two arguments, separated by whitespace. If one argument is specified, it is used as the packet class unconditionally. If two values are specified, the first is automatically selected for interactive sessions and the second for non-interactive sessions. The default is .Dq lowdelay for interactive sessions and .Dq throughput for non-interactive sessions. .It Cm KbdInteractiveAuthentication Specifies whether to allow keyboard-interactive authentication. The argument to this keyword must be .Dq yes or .Dq no . The default is to use whatever value .Cm ChallengeResponseAuthentication is set to (by default .Dq yes ) . .It Cm KerberosAuthentication Specifies whether the password provided by the user for .Cm PasswordAuthentication will be validated through the Kerberos KDC. To use this option, the server needs a Kerberos servtab which allows the verification of the KDC's identity. The default is .Dq no . .It Cm KerberosGetAFSToken If AFS is active and the user has a Kerberos 5 TGT, attempt to acquire an AFS token before accessing the user's home directory. The default is .Dq no . .It Cm KerberosOrLocalPasswd If password authentication through Kerberos fails then the password will be validated via any additional local mechanism such as .Pa /etc/passwd . The default is .Dq yes . .It Cm KerberosTicketCleanup Specifies whether to automatically destroy the user's ticket cache file on logout. The default is .Dq yes . .It Cm KexAlgorithms Specifies the available KEX (Key Exchange) algorithms. Multiple algorithms must be comma-separated. Alternately if the specified value begins with a .Sq + character, then the specified methods will be appended to the default set instead of replacing them. The supported algorithms are: .Pp .Bl -item -compact -offset indent .It curve25519-sha256@libssh.org .It diffie-hellman-group1-sha1 .It diffie-hellman-group14-sha1 .It diffie-hellman-group-exchange-sha1 .It diffie-hellman-group-exchange-sha256 .It ecdh-sha2-nistp256 .It ecdh-sha2-nistp384 .It ecdh-sha2-nistp521 .El .Pp The default is: .Bd -literal -offset indent curve25519-sha256@libssh.org, ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521, diffie-hellman-group-exchange-sha256, diffie-hellman-group14-sha1 .Ed .Pp The list of available key exchange algorithms may also be obtained using the .Fl Q option of .Xr ssh 1 with an argument of .Dq kex . .It Cm KeyRegenerationInterval In protocol version 1, the ephemeral server key is automatically regenerated after this many seconds (if it has been used). The purpose of regeneration is to prevent decrypting captured sessions by later breaking into the machine and stealing the keys. The key is never stored anywhere. If the value is 0, the key is never regenerated. The default is 3600 (seconds). .It Cm ListenAddress Specifies the local addresses .Xr sshd 8 should listen on. The following forms may be used: .Pp .Bl -item -offset indent -compact .It .Cm ListenAddress .Sm off .Ar host | Ar IPv4_addr | Ar IPv6_addr .Sm on .It .Cm ListenAddress .Sm off .Ar host | Ar IPv4_addr : Ar port .Sm on .It .Cm ListenAddress .Sm off .Oo .Ar host | Ar IPv6_addr Oc : Ar port .Sm on .El .Pp If .Ar port is not specified, sshd will listen on the address and all .Cm Port options specified. The default is to listen on all local addresses. Multiple .Cm ListenAddress options are permitted. .It Cm LoginGraceTime The server disconnects after this time if the user has not successfully logged in. If the value is 0, there is no time limit. The default is 120 seconds. .It Cm LogLevel Gives the verbosity level that is used when logging messages from .Xr sshd 8 . The possible values are: QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. The default is INFO. DEBUG and DEBUG1 are equivalent. DEBUG2 and DEBUG3 each specify higher levels of debugging output. Logging with a DEBUG level violates the privacy of users and is not recommended. .It Cm MACs Specifies the available MAC (message authentication code) algorithms. The MAC algorithm is used in protocol version 2 for data integrity protection. Multiple algorithms must be comma-separated. If the specified value begins with a .Sq + character, then the specified algorithms will be appended to the default set instead of replacing them. .Pp The algorithms that contain .Dq -etm calculate the MAC after encryption (encrypt-then-mac). These are considered safer and their use recommended. The supported MACs are: .Pp .Bl -item -compact -offset indent .It hmac-md5 .It hmac-md5-96 .It hmac-ripemd160 .It hmac-sha1 .It hmac-sha1-96 .It hmac-sha2-256 .It hmac-sha2-512 .It umac-64@openssh.com .It umac-128@openssh.com .It hmac-md5-etm@openssh.com .It hmac-md5-96-etm@openssh.com .It hmac-ripemd160-etm@openssh.com .It hmac-sha1-etm@openssh.com .It hmac-sha1-96-etm@openssh.com .It hmac-sha2-256-etm@openssh.com .It hmac-sha2-512-etm@openssh.com .It umac-64-etm@openssh.com .It umac-128-etm@openssh.com .El .Pp The default is: .Bd -literal -offset indent umac-64-etm@openssh.com,umac-128-etm@openssh.com, hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com, umac-64@openssh.com,umac-128@openssh.com, hmac-sha2-256,hmac-sha2-512 .Ed .Pp The list of available MAC algorithms may also be obtained using the .Fl Q option of .Xr ssh 1 with an argument of .Dq mac . .It Cm Match Introduces a conditional block. If all of the criteria on the .Cm Match line are satisfied, the keywords on the following lines override those set in the global section of the config file, until either another .Cm Match line or the end of the file. If a keyword appears in multiple .Cm Match blocks that are satisfied, only the first instance of the keyword is applied. .Pp The arguments to .Cm Match are one or more criteria-pattern pairs or the single token .Cm All which matches all criteria. The available criteria are .Cm User , .Cm Group , .Cm Host , .Cm LocalAddress , .Cm LocalPort , and .Cm Address . The match patterns may consist of single entries or comma-separated lists and may use the wildcard and negation operators described in the PATTERNS section of .Xr ssh_config 5 . .Pp The patterns in an .Cm Address criteria may additionally contain addresses to match in CIDR address/masklen format, e.g.\& .Dq 192.0.2.0/24 or .Dq 3ffe:ffff::/32 . Note that the mask length provided must be consistent with the address - it is an error to specify a mask length that is too long for the address or one with bits set in this host portion of the address. For example, .Dq 192.0.2.0/33 and .Dq 192.0.2.0/8 respectively. .Pp Only a subset of keywords may be used on the lines following a .Cm Match keyword. Available keywords are .Cm AcceptEnv , .Cm AllowAgentForwarding , .Cm AllowGroups , .Cm AllowStreamLocalForwarding , .Cm AllowTcpForwarding , .Cm AllowUsers , .Cm AuthenticationMethods , .Cm AuthorizedKeysCommand , .Cm AuthorizedKeysCommandUser , .Cm AuthorizedKeysFile , .Cm AuthorizedPrincipalsFile , .Cm Banner , .Cm ChrootDirectory , .Cm DenyGroups , .Cm DenyUsers , .Cm ForceCommand , .Cm GatewayPorts , .Cm GSSAPIAuthentication , .Cm HostbasedAcceptedKeyTypes , .Cm HostbasedAuthentication , .Cm HostbasedUsesNameFromPacketOnly , .Cm IPQoS , .Cm KbdInteractiveAuthentication , .Cm KerberosAuthentication , .Cm MaxAuthTries , .Cm MaxSessions , .Cm PasswordAuthentication , .Cm PermitEmptyPasswords , .Cm PermitOpen , .Cm PermitRootLogin , .Cm PermitTTY , .Cm PermitTunnel , .Cm PermitUserRC , .Cm PubkeyAcceptedKeyTypes , .Cm PubkeyAuthentication , .Cm RekeyLimit , .Cm RevokedKeys , .Cm RhostsRSAAuthentication , .Cm RSAAuthentication , .Cm StreamLocalBindMask , .Cm StreamLocalBindUnlink , .Cm TrustedUserCAKeys , .Cm X11DisplayOffset , .Cm X11Forwarding and .Cm X11UseLocalHost . .It Cm MaxAuthTries Specifies the maximum number of authentication attempts permitted per connection. Once the number of failures reaches half this value, additional failures are logged. The default is 6. .It Cm MaxSessions Specifies the maximum number of open sessions permitted per network connection. The default is 10. .It Cm MaxStartups Specifies the maximum number of concurrent unauthenticated connections to the SSH daemon. Additional connections will be dropped until authentication succeeds or the .Cm LoginGraceTime expires for a connection. The default is 10:30:100. .Pp Alternatively, random early drop can be enabled by specifying the three colon separated values .Dq start:rate:full (e.g. "10:30:60"). .Xr sshd 8 will refuse connection attempts with a probability of .Dq rate/100 (30%) if there are currently .Dq start (10) unauthenticated connections. The probability increases linearly and all connection attempts are refused if the number of unauthenticated connections reaches .Dq full (60). .It Cm PasswordAuthentication Specifies whether password authentication is allowed. See also .Cm UsePAM . The default is .Dq no . .It Cm PermitEmptyPasswords When password authentication is allowed, it specifies whether the server allows login to accounts with empty password strings. The default is .Dq no . .It Cm PermitOpen Specifies the destinations to which TCP port forwarding is permitted. The forwarding specification must be one of the following forms: .Pp .Bl -item -offset indent -compact .It .Cm PermitOpen .Sm off .Ar host : port .Sm on .It .Cm PermitOpen .Sm off .Ar IPv4_addr : port .Sm on .It .Cm PermitOpen .Sm off .Ar \&[ IPv6_addr \&] : port .Sm on .El .Pp Multiple forwards may be specified by separating them with whitespace. An argument of .Dq any can be used to remove all restrictions and permit any forwarding requests. An argument of .Dq none can be used to prohibit all forwarding requests. By default all port forwarding requests are permitted. .It Cm PermitRootLogin Specifies whether root can log in using .Xr ssh 1 . The argument must be .Dq yes , .Dq prohibit-password , .Dq without-password , .Dq forced-commands-only , or .Dq no . The default is .Dq prohibit-password . Note that if .Cm ChallengeResponseAuthentication is .Dq yes , the root user may be allowed in with its password even if .Cm PermitRootLogin is set to .Dq without-password . .Pp If this option is set to .Dq prohibit-password or .Dq without-password , password and keyboard-interactive authentication are disabled for root. .Pp If this option is set to .Dq forced-commands-only , root login with public key authentication will be allowed, but only if the .Ar command option has been specified (which may be useful for taking remote backups even if root login is normally not allowed). All other authentication methods are disabled for root. .Pp If this option is set to .Dq no , root is not allowed to log in. .It Cm PermitTunnel Specifies whether .Xr tun 4 device forwarding is allowed. The argument must be .Dq yes , .Dq point-to-point (layer 3), .Dq ethernet (layer 2), or .Dq no . Specifying .Dq yes permits both .Dq point-to-point and .Dq ethernet . The default is .Dq no . .Pp Independent of this setting, the permissions of the selected .Xr tun 4 device must allow access to the user. .It Cm PermitTTY Specifies whether .Xr pty 4 allocation is permitted. The default is .Dq yes . .It Cm PermitUserEnvironment Specifies whether .Pa ~/.ssh/environment and .Cm environment= options in .Pa ~/.ssh/authorized_keys are processed by .Xr sshd 8 . The default is .Dq no . Enabling environment processing may enable users to bypass access restrictions in some configurations using mechanisms such as .Ev LD_PRELOAD . .It Cm PermitUserRC Specifies whether any .Pa ~/.ssh/rc file is executed. The default is .Dq yes . .It Cm PidFile Specifies the file that contains the process ID of the SSH daemon, or .Dq none to not write one. The default is .Pa /var/run/sshd.pid . .It Cm Port Specifies the port number that .Xr sshd 8 listens on. The default is 22. Multiple options of this type are permitted. See also .Cm ListenAddress . .It Cm PrintLastLog Specifies whether .Xr sshd 8 should print the date and time of the last user login when a user logs in interactively. The default is .Dq yes . .It Cm PrintMotd Specifies whether .Xr sshd 8 should print .Pa /etc/motd when a user logs in interactively. (On some systems it is also printed by the shell, .Pa /etc/profile , or equivalent.) The default is .Dq yes . .It Cm Protocol Specifies the protocol versions .Xr sshd 8 supports. The possible values are .Sq 1 and .Sq 2 . Multiple versions must be comma-separated. The default is .Sq 2 . Note that the order of the protocol list does not indicate preference, because the client selects among multiple protocol versions offered by the server. Specifying .Dq 2,1 is identical to .Dq 1,2 . .It Cm PubkeyAcceptedKeyTypes Specifies the key types that will be accepted for public key authentication as a comma-separated pattern list. Alternately if the specified value begins with a .Sq + character, then the specified key types will be appended to the default set instead of replacing them. The default for this option is: .Bd -literal -offset 3n ecdsa-sha2-nistp256-cert-v01@openssh.com, ecdsa-sha2-nistp384-cert-v01@openssh.com, ecdsa-sha2-nistp521-cert-v01@openssh.com, ssh-ed25519-cert-v01@openssh.com, ssh-rsa-cert-v01@openssh.com, -ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, -ssh-ed25519,ssh-rsa +ssh-dss-cert-v01@openssh.com, +ecdsa-sha2-nistp256,ecdsa-sha2-nistp384, +ecdsa-sha2-nistp521,ssh-ed25519, +ssh-rsa,ssh-dss .Ed .Pp The .Fl Q option of .Xr ssh 1 may be used to list supported key types. .It Cm PubkeyAuthentication Specifies whether public key authentication is allowed. The default is .Dq yes . Note that this option applies to protocol version 2 only. .It Cm RekeyLimit Specifies the maximum amount of data that may be transmitted before the session key is renegotiated, optionally followed a maximum amount of time that may pass before the session key is renegotiated. The first argument is specified in bytes and may have a suffix of .Sq K , .Sq M , or .Sq G to indicate Kilobytes, Megabytes, or Gigabytes, respectively. The default is between .Sq 1G and .Sq 4G , depending on the cipher. The optional second value is specified in seconds and may use any of the units documented in the .Sx TIME FORMATS section. The default value for .Cm RekeyLimit is .Dq default none , which means that rekeying is performed after the cipher's default amount of data has been sent or received and no time based rekeying is done. This option applies to protocol version 2 only. .It Cm RevokedKeys Specifies revoked public keys file, or .Dq none to not use one. Keys listed in this file will be refused for public key authentication. Note that if this file is not readable, then public key authentication will be refused for all users. Keys may be specified as a text file, listing one public key per line, or as an OpenSSH Key Revocation List (KRL) as generated by .Xr ssh-keygen 1 . For more information on KRLs, see the KEY REVOCATION LISTS section in .Xr ssh-keygen 1 . .It Cm RhostsRSAAuthentication Specifies whether rhosts or .Pa /etc/hosts.equiv authentication together with successful RSA host authentication is allowed. The default is .Dq no . This option applies to protocol version 1 only. .It Cm RSAAuthentication Specifies whether pure RSA authentication is allowed. The default is .Dq yes . This option applies to protocol version 1 only. .It Cm ServerKeyBits Defines the number of bits in the ephemeral protocol version 1 server key. The default and minimum value is 1024. .It Cm StreamLocalBindMask Sets the octal file creation mode mask .Pq umask used when creating a Unix-domain socket file for local or remote port forwarding. This option is only used for port forwarding to a Unix-domain socket file. .Pp The default value is 0177, which creates a Unix-domain socket file that is readable and writable only by the owner. Note that not all operating systems honor the file mode on Unix-domain socket files. .It Cm StreamLocalBindUnlink Specifies whether to remove an existing Unix-domain socket file for local or remote port forwarding before creating a new one. If the socket file already exists and .Cm StreamLocalBindUnlink is not enabled, .Nm sshd will be unable to forward the port to the Unix-domain socket file. This option is only used for port forwarding to a Unix-domain socket file. .Pp The argument must be .Dq yes or .Dq no . The default is .Dq no . .It Cm StrictModes Specifies whether .Xr sshd 8 should check file modes and ownership of the user's files and home directory before accepting login. This is normally desirable because novices sometimes accidentally leave their directory or files world-writable. The default is .Dq yes . Note that this does not apply to .Cm ChrootDirectory , whose permissions and ownership are checked unconditionally. .It Cm Subsystem Configures an external subsystem (e.g. file transfer daemon). Arguments should be a subsystem name and a command (with optional arguments) to execute upon subsystem request. .Pp The command .Xr sftp-server 8 implements the .Dq sftp file transfer subsystem. .Pp Alternately the name .Dq internal-sftp implements an in-process .Dq sftp server. This may simplify configurations using .Cm ChrootDirectory to force a different filesystem root on clients. .Pp By default no subsystems are defined. Note that this option applies to protocol version 2 only. .It Cm SyslogFacility Gives the facility code that is used when logging messages from .Xr sshd 8 . The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2, LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7. The default is AUTH. .It Cm TCPKeepAlive Specifies whether the system should send TCP keepalive messages to the other side. If they are sent, death of the connection or crash of one of the machines will be properly noticed. However, this means that connections will die if the route is down temporarily, and some people find it annoying. On the other hand, if TCP keepalives are not sent, sessions may hang indefinitely on the server, leaving .Dq ghost users and consuming server resources. .Pp The default is .Dq yes (to send TCP keepalive messages), and the server will notice if the network goes down or the client host crashes. This avoids infinitely hanging sessions. .Pp To disable TCP keepalive messages, the value should be set to .Dq no . .It Cm TrustedUserCAKeys Specifies a file containing public keys of certificate authorities that are trusted to sign user certificates for authentication, or .Dq none to not use one. Keys are listed one per line; empty lines and comments starting with .Ql # are allowed. If a certificate is presented for authentication and has its signing CA key listed in this file, then it may be used for authentication for any user listed in the certificate's principals list. Note that certificates that lack a list of principals will not be permitted for authentication using .Cm TrustedUserCAKeys . For more details on certificates, see the CERTIFICATES section in .Xr ssh-keygen 1 . .It Cm UseDNS Specifies whether .Xr sshd 8 should look up the remote host name, and to check that the resolved host name for the remote IP address maps back to the very same IP address. .Pp If this option is set to .Dq no (the default) then only addresses and not host names may be used in .Pa ~/.ssh/known_hosts .Cm from and .Xr sshd_config 5 .Cm Match .Cm Host directives. .It Cm UseLogin Specifies whether .Xr login 1 is used for interactive login sessions. The default is .Dq no . Note that .Xr login 1 is never used for remote command execution. Note also, that if this is enabled, .Cm X11Forwarding will be disabled because .Xr login 1 does not know how to handle .Xr xauth 1 cookies. If .Cm UsePrivilegeSeparation is specified, it will be disabled after authentication. .It Cm UsePAM Enables the Pluggable Authentication Module interface. If set to .Dq yes this will enable PAM authentication using .Cm ChallengeResponseAuthentication and .Cm PasswordAuthentication in addition to PAM account and session module processing for all authentication types. .Pp Because PAM challenge-response authentication usually serves an equivalent role to password authentication, you should disable either .Cm PasswordAuthentication or .Cm ChallengeResponseAuthentication. .Pp If .Cm UsePAM is enabled, you will not be able to run .Xr sshd 8 as a non-root user. The default is .Dq yes . .It Cm UsePrivilegeSeparation Specifies whether .Xr sshd 8 separates privileges by creating an unprivileged child process to deal with incoming network traffic. After successful authentication, another process will be created that has the privilege of the authenticated user. The goal of privilege separation is to prevent privilege escalation by containing any corruption within the unprivileged processes. The default is .Dq sandbox . If .Cm UsePrivilegeSeparation is set to .Dq sandbox then the pre-authentication unprivileged process is subject to additional restrictions. .It Cm VersionAddendum Optionally specifies additional text to append to the SSH protocol banner sent by the server upon connection. The default is .Dq FreeBSD-20160119 . The value .Dq none may be used to disable this. .It Cm X11DisplayOffset Specifies the first display number available for .Xr sshd 8 Ns 's X11 forwarding. This prevents sshd from interfering with real X11 servers. The default is 10. .It Cm X11Forwarding Specifies whether X11 forwarding is permitted. The argument must be .Dq yes or .Dq no . The default is .Dq yes . .Pp When X11 forwarding is enabled, there may be additional exposure to the server and to client displays if the .Xr sshd 8 proxy display is configured to listen on the wildcard address (see .Cm X11UseLocalhost below), though this is not the default. Additionally, the authentication spoofing and authentication data verification and substitution occur on the client side. The security risk of using X11 forwarding is that the client's X11 display server may be exposed to attack when the SSH client requests forwarding (see the warnings for .Cm ForwardX11 in .Xr ssh_config 5 ) . A system administrator may have a stance in which they want to protect clients that may expose themselves to attack by unwittingly requesting X11 forwarding, which can warrant a .Dq no setting. .Pp Note that disabling X11 forwarding does not prevent users from forwarding X11 traffic, as users can always install their own forwarders. X11 forwarding is automatically disabled if .Cm UseLogin is enabled. .It Cm X11UseLocalhost Specifies whether .Xr sshd 8 should bind the X11 forwarding server to the loopback address or to the wildcard address. By default, sshd binds the forwarding server to the loopback address and sets the hostname part of the .Ev DISPLAY environment variable to .Dq localhost . This prevents remote hosts from connecting to the proxy display. However, some older X11 clients may not function with this configuration. .Cm X11UseLocalhost may be set to .Dq no to specify that the forwarding server should be bound to the wildcard address. The argument must be .Dq yes or .Dq no . The default is .Dq yes . .It Cm XAuthLocation Specifies the full pathname of the .Xr xauth 1 program, or .Dq none to not use one. The default is .Pa /usr/local/bin/xauth . .El .Sh TIME FORMATS .Xr sshd 8 command-line arguments and configuration file options that specify time may be expressed using a sequence of the form: .Sm off .Ar time Op Ar qualifier , .Sm on where .Ar time is a positive integer value and .Ar qualifier is one of the following: .Pp .Bl -tag -width Ds -compact -offset indent .It Aq Cm none seconds .It Cm s | Cm S seconds .It Cm m | Cm M minutes .It Cm h | Cm H hours .It Cm d | Cm D days .It Cm w | Cm W weeks .El .Pp Each member of the sequence is added together to calculate the total time value. .Pp Time format examples: .Pp .Bl -tag -width Ds -compact -offset indent .It 600 600 seconds (10 minutes) .It 10m 10 minutes .It 1h30m 1 hour 30 minutes (90 minutes) .El .Sh FILES .Bl -tag -width Ds .It Pa /etc/ssh/sshd_config Contains configuration data for .Xr sshd 8 . This file should be writable by root only, but it is recommended (though not necessary) that it be world-readable. .El .Sh SEE ALSO .Xr sshd 8 .Sh AUTHORS OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re-added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. Niels Provos and Markus Friedl contributed support for privilege separation.