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				.\" $NetBSD: blacklistd.8,v 1.15 2016/03/11 17:16:40 christos Exp $
				.\"
				.\" Copyright (c) 2015 The NetBSD Foundation, Inc.
				.\" All rights reserved.
				.\"
				.\" This code is derived from software contributed to The NetBSD Foundation
				.\" by Christos Zoulas.
				.\"
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				.\" modification, are permitted provided that the following conditions
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				.\" 1. Redistributions of source code must retain the above copyright
				.\" notice, this list of conditions and the following disclaimer.
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				.\"
				.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
				.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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				.\" 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.
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				.Dd June 4, 2015
				.Dt BLACKLISTD 8
				.Os
				.Sh NAME
				.Nm blacklistd
				.Nd block and release ports on demand to avoid DoS abuse
				.Sh SYNOPSIS
				.Nm
				.Op Fl dfrv
				.Op Fl C Ar controlprog
				.Op Fl c Ar configfile
				.Op Fl D Ar dbfile
				.Op Fl P Ar sockpathsfile
				.Op Fl R Ar rulename
				.Op Fl s Ar sockpath
				.Op Fl t Ar timeout
				.Sh DESCRIPTION
				.Nm
				is a daemon similar to
				.Xr syslogd 8
				that listens to a sockets at paths specified in the
				.Ar sockpathsfile
				for notifications from other daemons about successful or failed connection
				attempts.
				If no such file is specified, then it only listens to the socket path
				specified by
				.Ar sockspath
				or if that is not specified to
				.Pa /var/run/blacklistd.sock .
				Each notification contains an (action, port, protocol, address, owner) tuple
				that identifies the remote connection and the action.
				This tuple is consulted against entries in
				.Ar configfile
				with syntax specified in
				.Xr blacklistd.conf 5 .
				If an entry is matched, a state entry is created for that tuple.
				Each entry contains a number of tries limit and a duration.
				.Pp
				If the action is
				.Dq add
				and the number of tries limit is reached, then a
				control script
				.Ar controlprog
				is invoked with arguments:
				.Bd -literal -offset indent
				control add <rulename> <proto> <address> <mask> <port>
				.Ed
				.Pp
				and should invoke a packet filter command to block the connection
				specified by the arguments.
				The
				.Ar rulename
				argument can be set from the command line (default
				.Dv blacklistd ) .
				The script could print a numerical id to stdout as a handle for
				the rule that can be used later to remove that connection, but
				that is not required as all information to remove the rule is
				kept.
				.Pp
				If the action is
				.Dq remove
				Then the same control script is invoked as:
				.Bd -literal -offset indent
				control remove <rulename> <proto> <address> <mask> <port> <id>
				.Ed
				.Pp
				where
				.Ar id
				is the number returned from the
				.Dq add
				action.
				.Pp
				.Nm
				maintains a database of known connections in
				.Ar dbfile .
				On startup it reads entries from that file, and updates its internal state.
				.Pp
				.Nm
				checks the list of active entries every
				.Ar timeout
				seconds (default
				.Dv 15 )
				and removes entries and block rules using the control program as necessary.
				.Pp
				The following options are available:
				.Bl -tag -width indent
				.It Fl C Ar controlprog
				Use
				.Ar controlprog
				to communicate with the packet filter, usually
				.Pa /libexec/blacklistd-helper .
				The following arguments are passed to the control program:
				.Bl -tag -width protocol
				.It action
				The action to perform:
				.Dv add ,
				.Dv rem ,
				or
				.Dv flush
				to add, remove or flush a firewall rule.
				.It name
				The rule name.
				.It protocol
				The optional protocol name (can be empty):
				.Dv tcp ,
				.Dv tcp6 ,
				.Dv udp ,
				.Dv udp6 .
				.It address
				The IPv4 or IPv6 numeric address to be blocked or released.
				.It mask
				The numeric mask to be applied to the blocked or released address
				.It port
				The optional numeric port to be blocked (can be empty).
				.It id
				For packet filters that support removal of rules by rule identifier, the
				identifier of the rule to be removed.
				The add command is expected to return the rule identifier string to stdout.
				.El
				.It Fl c Ar configuration
				The name of the configuration file to read, usually
				.Pa /etc/blacklistd.conf .
				.It Fl D Ar dbfile
				The Berkeley DB file where
				.Nm
				stores its state, usually
				.Pa /var/run/blacklistd.db .
				.It Fl d
				Normally,
				.Nm
				disassociates itself from the terminal unless the
				.Fl d
				flag is specified, in which case it stays in the foreground.
				.It Fl f
				Truncate the state database and flush all the rules named
				.Ar rulename
				are deleted by invoking the control script as:
				.Bd -literal -offset indent
				control flush <rulename>
				.Ed
				.It Fl P Ar sockspathsfile
				A file containing a list of pathnames, one per line that
				.Nm
				will create sockets to listen to.
				This is useful for chrooted environments.
				.It Fl R Ar rulename
				Specify the default rule name for the packet filter rules, usually
				.Dv blacklistd .
				.It Fl r
				Re-read the firewall rules from the internal database, then
				remove and re-add them.
				This helps for packet filters that don't retain state across reboots.
				.It Fl s Ar sockpath
				Add
				.Ar sockpath
				to the list of Unix sockets
				.Nm
				listens to.
				.It Fl t Ar timeout
				The interval in seconds
				.Nm
				polls the state file to update the rules.
				.It Fl v
				Cause
				.Nm
				to print
				diagnostic messages to
				.Dv stdout
				instead of
				.Xr syslogd 8 .
				.El
				.Sh FILES
				.Bl -tag -width /libexec/blacklistd-helper -compact
				.It Pa /libexec/blacklistd-helper
				Shell script invoked to interface with the packet filter.
				.It Pa /etc/blacklistd.conf
				Configuration file.
				.It Pa /var/db/blacklistd.db
				Database of current connection entries.
				.It Pa /var/run/blacklistd.sock
				Socket to receive connection notifications.
				.El
				.Sh SEE ALSO
				.Xr blacklistd.conf 5 ,
				.Xr blacklistctl 8 ,
				.Xr npfctl 8 ,
				.Xr syslogd 8
				.Sh HISTORY
				.Nm
				appeared in
				.Nx 7 .
				.Sh AUTHORS
				.An Christos Zoulas