Index: head/contrib/telnet/telnetd/telnetd.8 =================================================================== --- head/contrib/telnet/telnetd/telnetd.8 (revision 139712) +++ head/contrib/telnet/telnetd/telnetd.8 (revision 139713) @@ -1,587 +1,595 @@ .\" Copyright (c) 1983, 1993 .\" The Regents of the University of California. 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. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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. .\" .\" @(#)telnetd.8 8.4 (Berkeley) 6/1/94 .\" $FreeBSD$ .\" -.Dd January 27, 2000 +.Dd January 5, 2005 .Dt TELNETD 8 .Os .Sh NAME .Nm telnetd .Nd DARPA .Tn TELNET protocol server .Sh SYNOPSIS .Nm /usr/libexec/telnetd -.Op Fl BUhlkn +.Op Fl 46BUhlkn .Op Fl D Ar debugmode .Op Fl S Ar tos .Op Fl X Ar authtype .Op Fl a Ar authmode .Op Fl edebug .Op Fl p Ar loginprog .Op Fl u Ar len .Op Fl debug Op Ar port .Sh DESCRIPTION The .Nm command is a server which supports the .Tn DARPA standard .Tn TELNET virtual terminal protocol. .Nm Telnetd is normally invoked by the internet server (see .Xr inetd 8 ) for requests to connect to the .Tn TELNET port as indicated by the .Pa /etc/services file (see .Xr services 5 ) . The .Fl debug option may be used to start up .Nm manually, instead of through .Xr inetd 8 . If started up this way, .Ar port may be specified to run .Nm on an alternate .Tn TCP port number. .Pp The .Nm command accepts the following options: .Bl -tag -width indent +.It Fl 4 +Forces +.Nm +to use IPv4 addresses only. +.It Fl 6 +Forces +.Nm +to use IPv6 addresses only. .It Fl a Ar authmode This option may be used for specifying what mode should be used for authentication. Note that this option is only useful if .Nm has been compiled with support for the .Dv AUTHENTICATION option. There are several valid values for .Ar authmode : .Bl -tag -width debug .It Cm debug Turn on authentication debugging code. .It Cm user Only allow connections when the remote user can provide valid authentication information to identify the remote user, and is allowed access to the specified account without providing a password. .It Cm valid Only allow connections when the remote user can provide valid authentication information to identify the remote user. The .Xr login 1 command will provide any additional user verification needed if the remote user is not allowed automatic access to the specified account. .It Cm other Only allow connections that supply some authentication information. This option is currently not supported by any of the existing authentication mechanisms, and is thus the same as specifying .Fl a .Cm valid . .It Cm none This is the default state. Authentication information is not required. If no or insufficient authentication information is provided, then the .Xr login 1 program will provide the necessary user verification. .It Cm off Disable the authentication code. All user verification will happen through the .Xr login 1 program. .El .It Fl B Specify bftp server mode. In this mode, .Nm causes login to start a .Xr bftp 1 session rather than the user's normal shell. In bftp daemon mode normal logins are not supported, and it must be used on a port other than the normal .Tn TELNET port. .It Fl D Ar debugmode This option may be used for debugging purposes. This allows .Nm to print out debugging information to the connection, allowing the user to see what .Nm is doing. There are several possible values for .Ar debugmode : .Bl -tag -width exercise .It Cm options Print information about the negotiation of .Tn TELNET options. .It Cm report Print the .Cm options information, plus some additional information about what processing is going on. .It Cm netdata Display the data stream received by .Nm . .It Cm ptydata Display data written to the pty. .It Cm exercise Has not been implemented yet. .El .It Fl debug Enable debugging on each socket created by .Nm (see .Dv SO_DEBUG in .Xr socket 2 ) . .It Fl edebug If .Nm has been compiled with support for data encryption, then the .Fl edebug option may be used to enable encryption debugging code. .It Fl h Disable the printing of host-specific information before login has been completed. .It Fl k This option is only useful if .Nm has been compiled with both linemode and kludge linemode support. If the .Fl k option is specified, then if the remote client does not support the .Dv LINEMODE option, then .Nm will operate in character at a time mode. It will still support kludge linemode, but will only go into kludge linemode if the remote client requests it. (This is done by the client sending .Dv DONT SUPPRESS-GO-AHEAD and .Dv DONT ECHO . ) The .Fl k option is most useful when there are remote clients that do not support kludge linemode, but pass the heuristic (if they respond with .Dv WILL TIMING-MARK in response to a .Dv DO TIMING-MARK ) for kludge linemode support. .It Fl l Specify line mode. Try to force clients to use line- at-a-time mode. If the .Dv LINEMODE option is not supported, it will go into kludge linemode. .It Fl n Disable .Dv TCP keep-alives. Normally .Nm enables the .Tn TCP keep-alive mechanism to probe connections that have been idle for some period of time to determine if the client is still there, so that idle connections from machines that have crashed or can no longer be reached may be cleaned up. .It Fl p Ar loginprog Specify an alternate .Xr login 1 command to run to complete the login. The alternate command must understand the same command arguments as the standard login. .It Fl S Ar tos .It Fl u Ar len This option is used to specify the size of the field in the .Dv utmp structure that holds the remote host name. If the resolved host name is longer than .Ar len , the dotted decimal value will be used instead. This allows hosts with very long host names that overflow this field to still be uniquely identified. Specifying .Fl u0 indicates that only dotted decimal addresses should be put into the .Pa utmp file. .It Fl U This option causes .Nm to refuse connections from addresses that cannot be mapped back into a symbolic name via the .Xr gethostbyaddr 3 routine. .It Fl X Ar authtype This option is only valid if .Nm has been built with support for the authentication option. It disables the use of .Ar authtype authentication, and can be used to temporarily disable a specific authentication type without having to recompile .Nm . .El .Pp .Nm Telnetd operates by allocating a pseudo-terminal device (see .Xr pty 4 ) for a client, then creating a login process which has the slave side of the pseudo-terminal as .Dv stdin , .Dv stdout and .Dv stderr . .Nm Telnetd manipulates the master side of the pseudo-terminal, implementing the .Tn TELNET protocol and passing characters between the remote client and the login process. .Pp When a .Tn TELNET session is started up, .Nm sends .Tn TELNET options to the client side indicating a willingness to do the following .Tn TELNET options, which are described in more detail below: .Bd -literal -offset indent DO AUTHENTICATION WILL ENCRYPT DO TERMINAL TYPE DO TSPEED DO XDISPLOC DO NEW-ENVIRON DO ENVIRON WILL SUPPRESS GO AHEAD DO ECHO DO LINEMODE DO NAWS WILL STATUS DO LFLOW DO TIMING-MARK .Ed .Pp The pseudo-terminal allocated to the client is configured to operate in .Dq cooked mode, and with .Dv XTABS and .Dv CRMOD enabled (see .Xr tty 4 ) . .Pp .Nm Telnetd has support for enabling locally the following .Tn TELNET options: .Bl -tag -width "DO AUTHENTICATION" .It "WILL ECHO" When the .Dv LINEMODE option is enabled, a .Dv WILL ECHO or .Dv WONT ECHO will be sent to the client to indicate the current state of terminal echoing. When terminal echo is not desired, a .Dv WILL ECHO is sent to indicate that .Nm will take care of echoing any data that needs to be echoed to the terminal, and then nothing is echoed. When terminal echo is desired, a .Dv WONT ECHO is sent to indicate that .Nm will not be doing any terminal echoing, so the client should do any terminal echoing that is needed. .It "WILL BINARY" Indicate that the client is willing to send a 8 bits of data, rather than the normal 7 bits of the Network Virtual Terminal. .It "WILL SGA" Indicate that it will not be sending .Dv IAC GA , go ahead, commands. .It "WILL STATUS" Indicate a willingness to send the client, upon request, of the current status of all .Tn TELNET options. .It "WILL TIMING-MARK" Whenever a .Dv DO TIMING-MARK command is received, it is always responded to with a .Dv WILL TIMING-MARK . .It "WILL LOGOUT" When a .Dv DO LOGOUT is received, a .Dv WILL LOGOUT is sent in response, and the .Tn TELNET session is shut down. .It "WILL ENCRYPT" Only sent if .Nm is compiled with support for data encryption, and indicates a willingness to decrypt the data stream. .El .Pp .Nm Telnetd has support for enabling remotely the following .Tn TELNET options: .Bl -tag -width "DO AUTHENTICATION" .It "DO BINARY" Sent to indicate that .Nm is willing to receive an 8 bit data stream. .It "DO LFLOW" Requests that the client handle flow control characters remotely. .It "DO ECHO" This is not really supported, but is sent to identify a .Bx 4.2 .Xr telnet 1 client, which will improperly respond with .Dv WILL ECHO . If a .Dv WILL ECHO is received, a .Dv DONT ECHO will be sent in response. .It "DO TERMINAL-TYPE" Indicate a desire to be able to request the name of the type of terminal that is attached to the client side of the connection. .It "DO SGA" Indicate that it does not need to receive .Dv IAC GA , the go ahead command. .It "DO NAWS" Requests that the client inform the server when the window (display) size changes. .It "DO TERMINAL-SPEED" Indicate a desire to be able to request information about the speed of the serial line to which the client is attached. .It "DO XDISPLOC" Indicate a desire to be able to request the name of the X Window System display that is associated with the telnet client. .It "DO NEW-ENVIRON" Indicate a desire to be able to request environment variable information, as described in RFC 1572. .It "DO ENVIRON" Indicate a desire to be able to request environment variable information, as described in RFC 1408. .It "DO LINEMODE" Only sent if .Nm is compiled with support for linemode, and requests that the client do line by line processing. .It "DO TIMING-MARK" Only sent if .Nm is compiled with support for both linemode and kludge linemode, and the client responded with .Dv WONT LINEMODE . If the client responds with .Dv WILL TM , the it is assumed that the client supports kludge linemode. Note that the .Op Fl k option can be used to disable this. .It "DO AUTHENTICATION" Only sent if .Nm is compiled with support for authentication, and indicates a willingness to receive authentication information for automatic login. .It "DO ENCRYPT" Only sent if .Nm is compiled with support for data encryption, and indicates a willingness to decrypt the data stream. .El .Sh NOTES By default .Nm will read the .Em \&he , .Em \&hn , and .Em \&im capabilities from .Pa /etc/gettytab and use that information (if present) to determine what to display before the login: prompt. You can also use a System V style .Pa /etc/issue file by using the .Em \&if capability, which will override .Em \&im . The information specified in either .Em \&im or .Em \&if will be displayed to both console and remote logins. .\" .Sh ENVIRONMENT .Sh FILES .Bl -tag -width /usr/ucb/bftp -compact .It Pa /etc/services .It Pa /etc/gettytab .It Pa /etc/iptos (if supported) .It Pa /usr/ucb/bftp (if supported) .El .Sh "SEE ALSO" .Xr bftp 1 , .Xr login 1 , .Xr gettytab 5 , .Xr telnet 1 (if supported) .Sh STANDARDS .Bl -tag -compact -width RFC-1572 .It Cm RFC-854 .Tn TELNET PROTOCOL SPECIFICATION .It Cm RFC-855 TELNET OPTION SPECIFICATIONS .It Cm RFC-856 TELNET BINARY TRANSMISSION .It Cm RFC-857 TELNET ECHO OPTION .It Cm RFC-858 TELNET SUPPRESS GO AHEAD OPTION .It Cm RFC-859 TELNET STATUS OPTION .It Cm RFC-860 TELNET TIMING MARK OPTION .It Cm RFC-861 TELNET EXTENDED OPTIONS - LIST OPTION .It Cm RFC-885 TELNET END OF RECORD OPTION .It Cm RFC-1073 Telnet Window Size Option .It Cm RFC-1079 Telnet Terminal Speed Option .It Cm RFC-1091 Telnet Terminal-Type Option .It Cm RFC-1096 Telnet X Display Location Option .It Cm RFC-1123 Requirements for Internet Hosts -- Application and Support .It Cm RFC-1184 Telnet Linemode Option .It Cm RFC-1372 Telnet Remote Flow Control Option .It Cm RFC-1416 Telnet Authentication Option .It Cm RFC-1411 Telnet Authentication: Kerberos Version 4 .It Cm RFC-1412 Telnet Authentication: SPX .It Cm RFC-1571 Telnet Environment Option Interoperability Issues .It Cm RFC-1572 Telnet Environment Option .El .Sh BUGS Some .Tn TELNET commands are only partially implemented. .Pp Because of bugs in the original .Bx 4.2 .Xr telnet 1 , .Nm performs some dubious protocol exchanges to try to discover if the remote client is, in fact, a .Bx 4.2 .Xr telnet 1 . .Pp Binary mode has no common interpretation except between similar operating systems (Unix in this case). .Pp The terminal type name received from the remote client is converted to lower case. .Pp .Nm Telnetd never sends .Tn TELNET .Dv IAC GA (go ahead) commands. .Sh HISTORY IPv6 support was added by WIDE/KAME project. Index: head/contrib/telnet/telnetd/telnetd.c =================================================================== --- head/contrib/telnet/telnetd/telnetd.c (revision 139712) +++ head/contrib/telnet/telnetd/telnetd.c (revision 139713) @@ -1,1231 +1,1232 @@ /* * Copyright (c) 1989, 1993 * The Regents of the University of California. 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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. */ #if 0 #ifndef lint static const char sccsid[] = "@(#)telnetd.c 8.4 (Berkeley) 5/30/95"; #endif #endif #include __FBSDID("$FreeBSD$"); #include "telnetd.h" #include "pathnames.h" #include #include #include #include #include #include #include #ifdef AUTHENTICATION #include int auth_level = 0; #endif #ifdef ENCRYPTION #include #endif #include char remote_hostname[MAXHOSTNAMELEN]; size_t utmp_len = sizeof(remote_hostname) - 1; int registerd_host_only = 0; /* * I/O data buffers, * pointers, and counters. */ char ptyibuf[BUFSIZ], *ptyip = ptyibuf; char ptyibuf2[BUFSIZ]; int readstream(int, char *, int); void doit(struct sockaddr *); int terminaltypeok(char *); int hostinfo = 1; /* do we print login banner? */ static int debug = 0; int keepalive = 1; const char *altlogin; void doit(struct sockaddr *); int terminaltypeok(char *); void startslave(char *, int, char *); extern void usage(void); static void _gettermname(void); /* * The string to pass to getopt(). We do it this way so * that only the actual options that we support will be * passed off to getopt(). */ char valid_opts[] = { 'd', ':', 'h', 'k', 'n', 'p', ':', 'S', ':', 'u', ':', 'U', '4', '6', #ifdef AUTHENTICATION 'a', ':', 'X', ':', #endif #ifdef BFTPDAEMON 'B', #endif #ifdef DIAGNOSTICS 'D', ':', #endif #ifdef ENCRYPTION 'e', ':', #endif #ifdef LINEMODE 'l', #endif '\0' }; int family = AF_INET; #ifndef MAXHOSTNAMELEN #define MAXHOSTNAMELEN 256 #endif /* MAXHOSTNAMELEN */ char *hostname; char host_name[MAXHOSTNAMELEN]; extern void telnet(int, int, char *); int level; char user_name[256]; int main(int argc, char *argv[]) { struct sockaddr_storage from; int on = 1, fromlen; int ch; #if defined(IPPROTO_IP) && defined(IP_TOS) int tos = -1; #endif pfrontp = pbackp = ptyobuf; netip = netibuf; nfrontp = nbackp = netobuf; #ifdef ENCRYPTION nclearto = 0; #endif /* ENCRYPTION */ /* * This initialization causes linemode to default to a configuration * that works on all telnet clients, including the FreeBSD client. * This is not quite the same as the telnet client issuing a "mode * character" command, but has most of the same benefits, and is * preferable since some clients (like usofts) don't have the * mode character command anyway and linemode breaks things. * The most notable symptom of fix is that csh "set filec" operations * like (filename completion) and ^D (choices) keys now work * in telnet sessions and can be used more than once on the same line. * CR/LF handling is also corrected in some termio modes. This * change resolves problem reports bin/771 and bin/1037. */ linemode=1; /*Default to mode that works on bulk of clients*/ while ((ch = getopt(argc, argv, valid_opts)) != -1) { switch(ch) { #ifdef AUTHENTICATION case 'a': /* * Check for required authentication level */ if (strcmp(optarg, "debug") == 0) { extern int auth_debug_mode; auth_debug_mode = 1; } else if (strcasecmp(optarg, "none") == 0) { auth_level = 0; } else if (strcasecmp(optarg, "other") == 0) { auth_level = AUTH_OTHER; } else if (strcasecmp(optarg, "user") == 0) { auth_level = AUTH_USER; } else if (strcasecmp(optarg, "valid") == 0) { auth_level = AUTH_VALID; } else if (strcasecmp(optarg, "off") == 0) { /* * This hack turns off authentication */ auth_level = -1; } else { warnx("unknown authorization level for -a"); } break; #endif /* AUTHENTICATION */ #ifdef BFTPDAEMON case 'B': bftpd++; break; #endif /* BFTPDAEMON */ case 'd': if (strcmp(optarg, "ebug") == 0) { debug++; break; } usage(); /* NOTREACHED */ break; #ifdef DIAGNOSTICS case 'D': /* * Check for desired diagnostics capabilities. */ if (!strcmp(optarg, "report")) { diagnostic |= TD_REPORT|TD_OPTIONS; } else if (!strcmp(optarg, "exercise")) { diagnostic |= TD_EXERCISE; } else if (!strcmp(optarg, "netdata")) { diagnostic |= TD_NETDATA; } else if (!strcmp(optarg, "ptydata")) { diagnostic |= TD_PTYDATA; } else if (!strcmp(optarg, "options")) { diagnostic |= TD_OPTIONS; } else { usage(); /* NOT REACHED */ } break; #endif /* DIAGNOSTICS */ #ifdef ENCRYPTION case 'e': if (strcmp(optarg, "debug") == 0) { extern int encrypt_debug_mode; encrypt_debug_mode = 1; break; } usage(); /* NOTREACHED */ break; #endif /* ENCRYPTION */ case 'h': hostinfo = 0; break; #ifdef LINEMODE case 'l': alwayslinemode = 1; break; #endif /* LINEMODE */ case 'k': #if defined(LINEMODE) && defined(KLUDGELINEMODE) lmodetype = NO_AUTOKLUDGE; #else /* ignore -k option if built without kludge linemode */ #endif /* defined(LINEMODE) && defined(KLUDGELINEMODE) */ break; case 'n': keepalive = 0; break; case 'p': altlogin = optarg; break; case 'S': #ifdef HAS_GETTOS if ((tos = parsetos(optarg, "tcp")) < 0) warnx("%s%s%s", "bad TOS argument '", optarg, "'; will try to use default TOS"); #else warnx("TOS option unavailable; -S flag not supported"); #endif break; case 'u': utmp_len = (size_t)atoi(optarg); if (utmp_len >= sizeof(remote_hostname)) utmp_len = sizeof(remote_hostname) - 1; break; case 'U': registerd_host_only = 1; break; #ifdef AUTHENTICATION case 'X': /* * Check for invalid authentication types */ auth_disable_name(optarg); break; #endif /* AUTHENTICATION */ case '4': family = AF_INET; break; #ifdef INET6 case '6': family = AF_INET6; break; #endif default: warnx("%c: unknown option", ch); /* FALLTHROUGH */ case '?': usage(); /* NOTREACHED */ } } argc -= optind; argv += optind; if (debug) { int s, ns, foo, error; const char *service = "telnet"; struct addrinfo hints, *res; if (argc > 1) { usage(); /* NOT REACHED */ } else if (argc == 1) service = *argv; memset(&hints, 0, sizeof(hints)); hints.ai_flags = AI_PASSIVE; hints.ai_family = family; hints.ai_socktype = SOCK_STREAM; hints.ai_protocol = 0; error = getaddrinfo(NULL, service, &hints, &res); if (error) { errx(1, "tcp/%s: %s\n", service, gai_strerror(error)); if (error == EAI_SYSTEM) errx(1, "tcp/%s: %s\n", service, strerror(errno)); usage(); } s = socket(res->ai_family, res->ai_socktype, res->ai_protocol); if (s < 0) err(1, "socket"); (void) setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *)&on, sizeof(on)); if (debug > 1) (void) setsockopt(s, SOL_SOCKET, SO_DEBUG, (char *)&on, sizeof(on)); if (bind(s, res->ai_addr, res->ai_addrlen) < 0) err(1, "bind"); if (listen(s, 1) < 0) err(1, "listen"); foo = res->ai_addrlen; ns = accept(s, res->ai_addr, &foo); if (ns < 0) err(1, "accept"); (void) setsockopt(ns, SOL_SOCKET, SO_DEBUG, (char *)&on, sizeof(on)); (void) dup2(ns, 0); (void) close(ns); (void) close(s); #ifdef convex } else if (argc == 1) { ; /* VOID*/ /* Just ignore the host/port name */ #endif } else if (argc > 0) { usage(); /* NOT REACHED */ } openlog("telnetd", LOG_PID | LOG_ODELAY, LOG_DAEMON); fromlen = sizeof (from); if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) { warn("getpeername"); _exit(1); } if (keepalive && setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, (char *)&on, sizeof (on)) < 0) { syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m"); } #if defined(IPPROTO_IP) && defined(IP_TOS) if (from.ss_family == AF_INET) { # if defined(HAS_GETTOS) struct tosent *tp; if (tos < 0 && (tp = gettosbyname("telnet", "tcp"))) tos = tp->t_tos; # endif if (tos < 0) tos = 020; /* Low Delay bit */ if (tos && (setsockopt(0, IPPROTO_IP, IP_TOS, (char *)&tos, sizeof(tos)) < 0) && (errno != ENOPROTOOPT) ) syslog(LOG_WARNING, "setsockopt (IP_TOS): %m"); } #endif /* defined(IPPROTO_IP) && defined(IP_TOS) */ net = 0; doit((struct sockaddr *)&from); /* NOTREACHED */ return(0); } /* end of main */ void usage() { fprintf(stderr, "usage: telnetd"); #ifdef AUTHENTICATION - fprintf(stderr, " [-a (debug|other|user|valid|off|none)]\n\t"); + fprintf(stderr, + " [-4] [-6] [-a (debug|other|user|valid|off|none)]\n\t"); #endif #ifdef BFTPDAEMON fprintf(stderr, " [-B]"); #endif fprintf(stderr, " [-debug]"); #ifdef DIAGNOSTICS fprintf(stderr, " [-D (options|report|exercise|netdata|ptydata)]\n\t"); #endif #ifdef AUTHENTICATION fprintf(stderr, " [-edebug]"); #endif fprintf(stderr, " [-h]"); #if defined(LINEMODE) && defined(KLUDGELINEMODE) fprintf(stderr, " [-k]"); #endif #ifdef LINEMODE fprintf(stderr, " [-l]"); #endif fprintf(stderr, " [-n]"); fprintf(stderr, "\n\t"); #ifdef HAS_GETTOS fprintf(stderr, " [-S tos]"); #endif #ifdef AUTHENTICATION fprintf(stderr, " [-X auth-type]"); #endif fprintf(stderr, " [-u utmp_hostname_length] [-U]"); fprintf(stderr, " [port]\n"); exit(1); } /* * getterminaltype * * Ask the other end to send along its terminal type and speed. * Output is the variable terminaltype filled in. */ static unsigned char ttytype_sbbuf[] = { IAC, SB, TELOPT_TTYPE, TELQUAL_SEND, IAC, SE }; #ifndef AUTHENTICATION #define undef2 __unused #else #define undef2 #endif static int getterminaltype(char *name undef2) { int retval = -1; settimer(baseline); #ifdef AUTHENTICATION /* * Handle the Authentication option before we do anything else. */ send_do(TELOPT_AUTHENTICATION, 1); while (his_will_wont_is_changing(TELOPT_AUTHENTICATION)) ttloop(); if (his_state_is_will(TELOPT_AUTHENTICATION)) { retval = auth_wait(name); } #endif #ifdef ENCRYPTION send_will(TELOPT_ENCRYPT, 1); #endif /* ENCRYPTION */ send_do(TELOPT_TTYPE, 1); send_do(TELOPT_TSPEED, 1); send_do(TELOPT_XDISPLOC, 1); send_do(TELOPT_NEW_ENVIRON, 1); send_do(TELOPT_OLD_ENVIRON, 1); while ( #ifdef ENCRYPTION his_do_dont_is_changing(TELOPT_ENCRYPT) || #endif /* ENCRYPTION */ his_will_wont_is_changing(TELOPT_TTYPE) || his_will_wont_is_changing(TELOPT_TSPEED) || his_will_wont_is_changing(TELOPT_XDISPLOC) || his_will_wont_is_changing(TELOPT_NEW_ENVIRON) || his_will_wont_is_changing(TELOPT_OLD_ENVIRON)) { ttloop(); } #ifdef ENCRYPTION /* * Wait for the negotiation of what type of encryption we can * send with. If autoencrypt is not set, this will just return. */ if (his_state_is_will(TELOPT_ENCRYPT)) { encrypt_wait(); } #endif /* ENCRYPTION */ if (his_state_is_will(TELOPT_TSPEED)) { static unsigned char sb[] = { IAC, SB, TELOPT_TSPEED, TELQUAL_SEND, IAC, SE }; output_datalen(sb, sizeof sb); DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2);); } if (his_state_is_will(TELOPT_XDISPLOC)) { static unsigned char sb[] = { IAC, SB, TELOPT_XDISPLOC, TELQUAL_SEND, IAC, SE }; output_datalen(sb, sizeof sb); DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2);); } if (his_state_is_will(TELOPT_NEW_ENVIRON)) { static unsigned char sb[] = { IAC, SB, TELOPT_NEW_ENVIRON, TELQUAL_SEND, IAC, SE }; output_datalen(sb, sizeof sb); DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2);); } else if (his_state_is_will(TELOPT_OLD_ENVIRON)) { static unsigned char sb[] = { IAC, SB, TELOPT_OLD_ENVIRON, TELQUAL_SEND, IAC, SE }; output_datalen(sb, sizeof sb); DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2);); } if (his_state_is_will(TELOPT_TTYPE)) { output_datalen(ttytype_sbbuf, sizeof ttytype_sbbuf); DIAG(TD_OPTIONS, printsub('>', ttytype_sbbuf + 2, sizeof ttytype_sbbuf - 2);); } if (his_state_is_will(TELOPT_TSPEED)) { while (sequenceIs(tspeedsubopt, baseline)) ttloop(); } if (his_state_is_will(TELOPT_XDISPLOC)) { while (sequenceIs(xdisplocsubopt, baseline)) ttloop(); } if (his_state_is_will(TELOPT_NEW_ENVIRON)) { while (sequenceIs(environsubopt, baseline)) ttloop(); } if (his_state_is_will(TELOPT_OLD_ENVIRON)) { while (sequenceIs(oenvironsubopt, baseline)) ttloop(); } if (his_state_is_will(TELOPT_TTYPE)) { char first[256], last[256]; while (sequenceIs(ttypesubopt, baseline)) ttloop(); /* * If the other side has already disabled the option, then * we have to just go with what we (might) have already gotten. */ if (his_state_is_will(TELOPT_TTYPE) && !terminaltypeok(terminaltype)) { (void) strncpy(first, terminaltype, sizeof(first)-1); first[sizeof(first)-1] = '\0'; for(;;) { /* * Save the unknown name, and request the next name. */ (void) strncpy(last, terminaltype, sizeof(last)-1); last[sizeof(last)-1] = '\0'; _gettermname(); if (terminaltypeok(terminaltype)) break; if ((strncmp(last, terminaltype, sizeof(last)) == 0) || his_state_is_wont(TELOPT_TTYPE)) { /* * We've hit the end. If this is the same as * the first name, just go with it. */ if (strncmp(first, terminaltype, sizeof(first)) == 0) break; /* * Get the terminal name one more time, so that * RFC1091 compliant telnets will cycle back to * the start of the list. */ _gettermname(); if (strncmp(first, terminaltype, sizeof(first)) != 0) { (void) strncpy(terminaltype, first, sizeof(terminaltype)-1); terminaltype[sizeof(terminaltype)-1] = '\0'; } break; } } } } return(retval); } /* end of getterminaltype */ static void _gettermname(void) { /* * If the client turned off the option, * we can't send another request, so we * just return. */ if (his_state_is_wont(TELOPT_TTYPE)) return; settimer(baseline); output_datalen(ttytype_sbbuf, sizeof ttytype_sbbuf); DIAG(TD_OPTIONS, printsub('>', ttytype_sbbuf + 2, sizeof ttytype_sbbuf - 2);); while (sequenceIs(ttypesubopt, baseline)) ttloop(); } int terminaltypeok(char *s) { char buf[1024]; if (terminaltype == NULL) return(1); /* * tgetent() will return 1 if the type is known, and * 0 if it is not known. If it returns -1, it couldn't * open the database. But if we can't open the database, * it won't help to say we failed, because we won't be * able to verify anything else. So, we treat -1 like 1. */ if (tgetent(buf, s) == 0) return(0); return(1); } /* * Get a pty, scan input lines. */ void doit(struct sockaddr *who) { int err_; /* XXX */ int ptynum; /* * Find an available pty to use. */ #ifndef convex pty = getpty(&ptynum); if (pty < 0) fatal(net, "All network ports in use"); #else for (;;) { char *lp; if ((lp = getpty()) == NULL) fatal(net, "Out of ptys"); if ((pty = open(lp, 2)) >= 0) { strlcpy(line,lp,sizeof(line)); line[5] = 't'; break; } } #endif /* get name of connected client */ if (realhostname_sa(remote_hostname, sizeof(remote_hostname) - 1, who, who->sa_len) == HOSTNAME_INVALIDADDR && registerd_host_only) fatal(net, "Couldn't resolve your address into a host name.\r\n\ Please contact your net administrator"); remote_hostname[sizeof(remote_hostname) - 1] = '\0'; trimdomain(remote_hostname, UT_HOSTSIZE); if (!isdigit(remote_hostname[0]) && strlen(remote_hostname) > utmp_len) err_ = getnameinfo(who, who->sa_len, remote_hostname, sizeof(remote_hostname), NULL, 0, NI_NUMERICHOST|NI_WITHSCOPEID); /* XXX: do 'err_' check */ (void) gethostname(host_name, sizeof(host_name) - 1); host_name[sizeof(host_name) - 1] = '\0'; hostname = host_name; #ifdef AUTHENTICATION #ifdef ENCRYPTION /* The above #ifdefs should actually be "or"'ed, not "and"'ed. * This is a byproduct of needing "#ifdef" and not "#if defined()" * for unifdef. XXX MarkM */ auth_encrypt_init(hostname, remote_hostname, "TELNETD", 1); #endif #endif init_env(); /* * get terminal type. */ *user_name = 0; level = getterminaltype(user_name); setenv("TERM", terminaltype ? terminaltype : "network", 1); telnet(net, pty, remote_hostname); /* begin server process */ /*NOTREACHED*/ } /* end of doit */ /* * Main loop. Select from pty and network, and * hand data to telnet receiver finite state machine. */ void telnet(int f, int p, char *host) { int on = 1; #define TABBUFSIZ 512 char defent[TABBUFSIZ]; char defstrs[TABBUFSIZ]; #undef TABBUFSIZ char *HE; char *HN; char *IM; int nfd; /* * Initialize the slc mapping table. */ get_slc_defaults(); /* * Do some tests where it is desireable to wait for a response. * Rather than doing them slowly, one at a time, do them all * at once. */ if (my_state_is_wont(TELOPT_SGA)) send_will(TELOPT_SGA, 1); /* * Is the client side a 4.2 (NOT 4.3) system? We need to know this * because 4.2 clients are unable to deal with TCP urgent data. * * To find out, we send out a "DO ECHO". If the remote system * answers "WILL ECHO" it is probably a 4.2 client, and we note * that fact ("WILL ECHO" ==> that the client will echo what * WE, the server, sends it; it does NOT mean that the client will * echo the terminal input). */ send_do(TELOPT_ECHO, 1); #ifdef LINEMODE if (his_state_is_wont(TELOPT_LINEMODE)) { /* Query the peer for linemode support by trying to negotiate * the linemode option. */ linemode = 0; editmode = 0; send_do(TELOPT_LINEMODE, 1); /* send do linemode */ } #endif /* LINEMODE */ /* * Send along a couple of other options that we wish to negotiate. */ send_do(TELOPT_NAWS, 1); send_will(TELOPT_STATUS, 1); flowmode = 1; /* default flow control state */ restartany = -1; /* uninitialized... */ send_do(TELOPT_LFLOW, 1); /* * Spin, waiting for a response from the DO ECHO. However, * some REALLY DUMB telnets out there might not respond * to the DO ECHO. So, we spin looking for NAWS, (most dumb * telnets so far seem to respond with WONT for a DO that * they don't understand...) because by the time we get the * response, it will already have processed the DO ECHO. * Kludge upon kludge. */ while (his_will_wont_is_changing(TELOPT_NAWS)) ttloop(); /* * But... * The client might have sent a WILL NAWS as part of its * startup code; if so, we'll be here before we get the * response to the DO ECHO. We'll make the assumption * that any implementation that understands about NAWS * is a modern enough implementation that it will respond * to our DO ECHO request; hence we'll do another spin * waiting for the ECHO option to settle down, which is * what we wanted to do in the first place... */ if (his_want_state_is_will(TELOPT_ECHO) && his_state_is_will(TELOPT_NAWS)) { while (his_will_wont_is_changing(TELOPT_ECHO)) ttloop(); } /* * On the off chance that the telnet client is broken and does not * respond to the DO ECHO we sent, (after all, we did send the * DO NAWS negotiation after the DO ECHO, and we won't get here * until a response to the DO NAWS comes back) simulate the * receipt of a will echo. This will also send a WONT ECHO * to the client, since we assume that the client failed to * respond because it believes that it is already in DO ECHO * mode, which we do not want. */ if (his_want_state_is_will(TELOPT_ECHO)) { DIAG(TD_OPTIONS, output_data("td: simulating recv\r\n")); willoption(TELOPT_ECHO); } /* * Finally, to clean things up, we turn on our echo. This * will break stupid 4.2 telnets out of local terminal echo. */ if (my_state_is_wont(TELOPT_ECHO)) send_will(TELOPT_ECHO, 1); /* * Turn on packet mode */ (void) ioctl(p, TIOCPKT, (char *)&on); #if defined(LINEMODE) && defined(KLUDGELINEMODE) /* * Continuing line mode support. If client does not support * real linemode, attempt to negotiate kludge linemode by sending * the do timing mark sequence. */ if (lmodetype < REAL_LINEMODE) send_do(TELOPT_TM, 1); #endif /* defined(LINEMODE) && defined(KLUDGELINEMODE) */ /* * Call telrcv() once to pick up anything received during * terminal type negotiation, 4.2/4.3 determination, and * linemode negotiation. */ telrcv(); (void) ioctl(f, FIONBIO, (char *)&on); (void) ioctl(p, FIONBIO, (char *)&on); #if defined(SO_OOBINLINE) (void) setsockopt(net, SOL_SOCKET, SO_OOBINLINE, (char *)&on, sizeof on); #endif /* defined(SO_OOBINLINE) */ #ifdef SIGTSTP (void) signal(SIGTSTP, SIG_IGN); #endif #ifdef SIGTTOU /* * Ignoring SIGTTOU keeps the kernel from blocking us * in ttioct() in /sys/tty.c. */ (void) signal(SIGTTOU, SIG_IGN); #endif (void) signal(SIGCHLD, cleanup); #ifdef TIOCNOTTY { int t; t = open(_PATH_TTY, O_RDWR); if (t >= 0) { (void) ioctl(t, TIOCNOTTY, (char *)0); (void) close(t); } } #endif /* * Show banner that getty never gave. * * We put the banner in the pty input buffer. This way, it * gets carriage return null processing, etc., just like all * other pty --> client data. */ if (getent(defent, "default") == 1) { char *cp=defstrs; HE = Getstr("he", &cp); HN = Getstr("hn", &cp); IM = Getstr("im", &cp); if (HN && *HN) (void) strlcpy(host_name, HN, sizeof(host_name)); if (IM == 0) IM = strdup(""); } else { IM = strdup(DEFAULT_IM); HE = 0; } edithost(HE, host_name); if (hostinfo && *IM) putf(IM, ptyibuf2); if (pcc) (void) strncat(ptyibuf2, ptyip, pcc+1); ptyip = ptyibuf2; pcc = strlen(ptyip); #ifdef LINEMODE /* * Last check to make sure all our states are correct. */ init_termbuf(); localstat(); #endif /* LINEMODE */ DIAG(TD_REPORT, output_data("td: Entering processing loop\r\n")); /* * Startup the login process on the slave side of the terminal * now. We delay this until here to insure option negotiation * is complete. */ startslave(host, level, user_name); nfd = ((f > p) ? f : p) + 1; for (;;) { fd_set ibits, obits, xbits; int c; if (ncc < 0 && pcc < 0) break; FD_ZERO(&ibits); FD_ZERO(&obits); FD_ZERO(&xbits); /* * Never look for input if there's still * stuff in the corresponding output buffer */ if (nfrontp - nbackp || pcc > 0) { FD_SET(f, &obits); } else { FD_SET(p, &ibits); } if (pfrontp - pbackp || ncc > 0) { FD_SET(p, &obits); } else { FD_SET(f, &ibits); } if (!SYNCHing) { FD_SET(f, &xbits); } if ((c = select(nfd, &ibits, &obits, &xbits, (struct timeval *)0)) < 1) { if (c == -1) { if (errno == EINTR) { continue; } } sleep(5); continue; } /* * Any urgent data? */ if (FD_ISSET(net, &xbits)) { SYNCHing = 1; } /* * Something to read from the network... */ if (FD_ISSET(net, &ibits)) { #if !defined(SO_OOBINLINE) /* * In 4.2 (and 4.3 beta) systems, the * OOB indication and data handling in the kernel * is such that if two separate TCP Urgent requests * come in, one byte of TCP data will be overlaid. * This is fatal for Telnet, but we try to live * with it. * * In addition, in 4.2 (and...), a special protocol * is needed to pick up the TCP Urgent data in * the correct sequence. * * What we do is: if we think we are in urgent * mode, we look to see if we are "at the mark". * If we are, we do an OOB receive. If we run * this twice, we will do the OOB receive twice, * but the second will fail, since the second * time we were "at the mark", but there wasn't * any data there (the kernel doesn't reset * "at the mark" until we do a normal read). * Once we've read the OOB data, we go ahead * and do normal reads. * * There is also another problem, which is that * since the OOB byte we read doesn't put us * out of OOB state, and since that byte is most * likely the TELNET DM (data mark), we would * stay in the TELNET SYNCH (SYNCHing) state. * So, clocks to the rescue. If we've "just" * received a DM, then we test for the * presence of OOB data when the receive OOB * fails (and AFTER we did the normal mode read * to clear "at the mark"). */ if (SYNCHing) { int atmark; (void) ioctl(net, SIOCATMARK, (char *)&atmark); if (atmark) { ncc = recv(net, netibuf, sizeof (netibuf), MSG_OOB); if ((ncc == -1) && (errno == EINVAL)) { ncc = read(net, netibuf, sizeof (netibuf)); if (sequenceIs(didnetreceive, gotDM)) { SYNCHing = stilloob(net); } } } else { ncc = read(net, netibuf, sizeof (netibuf)); } } else { ncc = read(net, netibuf, sizeof (netibuf)); } settimer(didnetreceive); #else /* !defined(SO_OOBINLINE)) */ ncc = read(net, netibuf, sizeof (netibuf)); #endif /* !defined(SO_OOBINLINE)) */ if (ncc < 0 && errno == EWOULDBLOCK) ncc = 0; else { if (ncc <= 0) { break; } netip = netibuf; } DIAG((TD_REPORT | TD_NETDATA), output_data("td: netread %d chars\r\n", ncc)); DIAG(TD_NETDATA, printdata("nd", netip, ncc)); } /* * Something to read from the pty... */ if (FD_ISSET(p, &ibits)) { pcc = read(p, ptyibuf, BUFSIZ); /* * On some systems, if we try to read something * off the master side before the slave side is * opened, we get EIO. */ if (pcc < 0 && (errno == EWOULDBLOCK || #ifdef EAGAIN errno == EAGAIN || #endif errno == EIO)) { pcc = 0; } else { if (pcc <= 0) break; #ifdef LINEMODE /* * If ioctl from pty, pass it through net */ if (ptyibuf[0] & TIOCPKT_IOCTL) { copy_termbuf(ptyibuf+1, pcc-1); localstat(); pcc = 1; } #endif /* LINEMODE */ if (ptyibuf[0] & TIOCPKT_FLUSHWRITE) { netclear(); /* clear buffer back */ #ifndef NO_URGENT /* * There are client telnets on some * operating systems get screwed up * royally if we send them urgent * mode data. */ output_data("%c%c", IAC, DM); neturg = nfrontp-1; /* off by one XXX */ DIAG(TD_OPTIONS, printoption("td: send IAC", DM)); #endif } if (his_state_is_will(TELOPT_LFLOW) && (ptyibuf[0] & (TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))) { int newflow = ptyibuf[0] & TIOCPKT_DOSTOP ? 1 : 0; if (newflow != flowmode) { flowmode = newflow; output_data("%c%c%c%c%c%c", IAC, SB, TELOPT_LFLOW, flowmode ? LFLOW_ON : LFLOW_OFF, IAC, SE); DIAG(TD_OPTIONS, printsub('>', (unsigned char *)nfrontp-4, 4);); } } pcc--; ptyip = ptyibuf+1; } } while (pcc > 0) { if ((&netobuf[BUFSIZ] - nfrontp) < 2) break; c = *ptyip++ & 0377, pcc--; if (c == IAC) output_data("%c", c); output_data("%c", c); if ((c == '\r') && (my_state_is_wont(TELOPT_BINARY))) { if (pcc > 0 && ((*ptyip & 0377) == '\n')) { output_data("%c", *ptyip++ & 0377); pcc--; } else output_data("%c", '\0'); } } if (FD_ISSET(f, &obits) && (nfrontp - nbackp) > 0) netflush(); if (ncc > 0) telrcv(); if (FD_ISSET(p, &obits) && (pfrontp - pbackp) > 0) ptyflush(); } cleanup(0); } /* end of telnet */ #ifndef TCSIG # ifdef TIOCSIG # define TCSIG TIOCSIG # endif #endif /* * Send interrupt to process on other side of pty. * If it is in raw mode, just write NULL; * otherwise, write intr char. */ void interrupt(void) { ptyflush(); /* half-hearted */ #ifdef TCSIG (void) ioctl(pty, TCSIG, (char *)SIGINT); #else /* TCSIG */ init_termbuf(); *pfrontp++ = slctab[SLC_IP].sptr ? (unsigned char)*slctab[SLC_IP].sptr : '\177'; #endif /* TCSIG */ } /* * Send quit to process on other side of pty. * If it is in raw mode, just write NULL; * otherwise, write quit char. */ void sendbrk(void) { ptyflush(); /* half-hearted */ #ifdef TCSIG (void) ioctl(pty, TCSIG, (char *)SIGQUIT); #else /* TCSIG */ init_termbuf(); *pfrontp++ = slctab[SLC_ABORT].sptr ? (unsigned char)*slctab[SLC_ABORT].sptr : '\034'; #endif /* TCSIG */ } void sendsusp(void) { #ifdef SIGTSTP ptyflush(); /* half-hearted */ # ifdef TCSIG (void) ioctl(pty, TCSIG, (char *)SIGTSTP); # else /* TCSIG */ *pfrontp++ = slctab[SLC_SUSP].sptr ? (unsigned char)*slctab[SLC_SUSP].sptr : '\032'; # endif /* TCSIG */ #endif /* SIGTSTP */ } /* * When we get an AYT, if ^T is enabled, use that. Otherwise, * just send back "[Yes]". */ void recv_ayt(void) { #if defined(SIGINFO) && defined(TCSIG) if (slctab[SLC_AYT].sptr && *slctab[SLC_AYT].sptr != _POSIX_VDISABLE) { (void) ioctl(pty, TCSIG, (char *)SIGINFO); return; } #endif output_data("\r\n[Yes]\r\n"); } void doeof(void) { init_termbuf(); #if defined(LINEMODE) && defined(USE_TERMIO) && (VEOF == VMIN) if (!tty_isediting()) { extern char oldeofc; *pfrontp++ = oldeofc; return; } #endif *pfrontp++ = slctab[SLC_EOF].sptr ? (unsigned char)*slctab[SLC_EOF].sptr : '\004'; }