142 lines
4.1 KiB
Groff
142 lines
4.1 KiB
Groff
.\" $NetBSD: tftp-proxy.8,v 1.4 2009/03/22 14:29:35 perry Exp $
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.\" $OpenBSD: tftp-proxy.8,v 1.2 2007/05/31 19:19:41 jmc Exp $
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.\"
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.\" Copyright (c) 2005 joshua stein <jcs@openbsd.org>
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\"
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd May 31, 2007
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.Dt TFTP-PROXY 8
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.Os
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.Sh NAME
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.Nm tftp-proxy
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.Nd Internet Trivial File Transfer Protocol proxy
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.Sh SYNOPSIS
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.Nm tftp-proxy
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.Op Fl v
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.Op Fl w Ar transwait
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.Sh DESCRIPTION
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.Nm
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is a proxy for the Internet Trivial File Transfer Protocol invoked by
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the
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.Xr inetd 8
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internet server.
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TFTP connections should be redirected to the proxy using the
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.Xr pf 4
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.Ar rdr
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command, after which the proxy connects to the server on behalf of
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the client.
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.Pp
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The proxy establishes a
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.Xr pf 4
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.Ar rdr
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rule using the
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.Ar anchor
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facility to rewrite packets between the client and the server.
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Once the rule is established,
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.Nm
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forwards the initial request from the client to the server to begin the
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transfer.
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After
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.Ar transwait
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seconds, the
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.Xr pf 4
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NAT state is assumed to have been established and the
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.Ar rdr
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rule is deleted and the program exits.
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Once the transfer between the client and the server is completed, the
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NAT state will naturally expire.
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.Pp
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Assuming the TFTP command request is from $client to $server, the
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proxy connected to the server using the $proxy source address, and
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$port is negotiated,
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.Nm
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adds the following rule to the anchor:
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.Bd -literal -offset indent
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rdr proto udp from $server to $proxy port $port -\*(Gt $client
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.Ed
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.Pp
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The options are as follows:
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.Bl -tag -width Ds
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.It Fl v
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Log the connection and request information to
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.Xr syslogd 8 .
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.It Fl w Ar transwait
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Number of seconds to wait for the data transmission to begin before
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removing the
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.Xr pf 4
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.Ar rdr
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rule.
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The default is 2 seconds.
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.El
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.Sh CONFIGURATION
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To make use of the proxy,
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.Xr pf.conf 5
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needs the following rules.
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The anchors are mandatory.
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Adjust the rules as needed for your configuration.
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.Pp
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In the NAT section:
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.Bd -literal -offset indent
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nat on $ext_if from $int_if -\*(Gt ($ext_if:0)
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no nat on $ext_if to port tftp
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rdr-anchor "tftp-proxy/*"
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rdr on $int_if proto udp from $lan to any port tftp -\*(Gt \e
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127.0.0.1 port 6969
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.Ed
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.Pp
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In the filter section, an anchor must be added to hold the pass rules:
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.Bd -literal -offset indent
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anchor "tftp-proxy/*"
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.Ed
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.Pp
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.Xr inetd 8
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must be configured to spawn the proxy on the port that packets are
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being forwarded to by
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.Xr pf 4 .
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An example
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.Xr inetd.conf 5
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entry follows:
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.Bd -literal -offset indent
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127.0.0.1:6969 dgram udp wait root \e
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/usr/libexec/tftp-proxy tftp-proxy
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.Ed
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.Sh SEE ALSO
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.Xr tftp 1 ,
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.Xr pf 4 ,
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.Xr pf.conf 5 ,
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.Xr ftp-proxy 8 ,
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.Xr inetd 8 ,
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.Xr syslogd 8 ,
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.Xr tftpd 8
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.Sh CAVEATS
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.Nm
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chroots to
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.Pa /var/chroot/tftp-proxy
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and changes to user
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.Dq _proxy
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to drop privileges.
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