.\"	$OpenBSD: tftp-proxy.8,v 1.5 2013/12/23 13:07:47 florian Exp $
.\"
.\" Copyright (c) 2005 joshua stein <jcs@openbsd.org>
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.Dd $Mdocdate: December 23 2013 $
.Dt TFTP-PROXY 8
.Os
.Sh NAME
.Nm tftp-proxy
.Nd Internet Trivial File Transfer Protocol proxy
.Sh SYNOPSIS
.Nm tftp-proxy
.Op Fl 46dv
.Op Fl a Ar address
.Op Fl l Ar address
.Op Fl p Ar port
.Op Fl w Ar transwait
.Sh DESCRIPTION
.Nm
is a proxy for the Internet Trivial File Transfer Protocol.
TFTP connections should be redirected to the proxy using a
.Xr pf 4
rule using the
.Ar divert-to
option, after which the proxy connects to the server on behalf of
the client.
The connection from the proxy to the server needs to be passed by
a rule with divert-reply set.
.Pp
The proxy inserts
.Xr pf 4
pass and/or rdr rules using the
.Ar anchor
facility to allow payload packets between the client and the server.
Once the rules are inserted,
.Nm
forwards the initial request from the client to the server to begin the
transfer.
After
.Ar transwait
seconds, the states are assumed to have been established and the
.Xr pf 4
rules are deleted and the program exits.
Once the transfer between the client and the server is completed the
states will naturally expire.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl 4
Forces
.Nm
to use IPv4 addresses only.
.It Fl 6
Forces
.Nm
to use IPv6 addresses only.
.It Fl a Ar address
The proxy will use
.Ar address
as the source address for the initial request from the client to the server for
NAT traversal.
Instead of a
.Dq pass in
rule an
.Dq rdr
rule will be generated.
It is possible to have two
.Fl a
options to specify both an IPv4 and an IPv6 address.
.It Fl d
Do not daemonize.
If this option is specified,
.Nm
will run in the foreground and log
the client IP, type of request, and filename to stderr.
.It Fl l Ar address
Listen on the specified address.
By default
.Nm
listens on localhost addresses.
.It Fl p Ar port
Listen on the specified port.
By default
.Nm
listens on port 6969.
.It Fl v
Log the connection and request information to
.Xr syslogd 8 .
.It Fl w Ar transwait
Number of seconds to wait for the data transmission to begin before
removing the
.Xr pf 4
rule.
The default is 2 seconds.
.El
.Sh CONFIGURATION
To make use of the proxy,
.Xr pf.conf 5
needs the following rules.
The anchor is mandatory.
Adjust the rule as needed for your configuration.
.Bd -literal -offset indent
anchor "tftp-proxy/*"
pass in quick on $int_if inet proto udp from $lan to port tftp \e
    divert-to 127.0.0.1 port 6969
pass out quick on $ext_if inet proto udp from $lan to port tftp \e
    group proxy divert-reply
.Ed
.Sh SEE ALSO
.Xr tftp 1 ,
.Xr pf 4 ,
.Xr pf.conf 5 ,
.Xr ftp-proxy 8 ,
.Xr syslogd 8 ,
.Xr tftpd 8
.Sh CAVEATS
.Nm
chroots to
.Pa /var/empty
and changes to user
.Dq proxy
to drop privileges.