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A TCP port redirector for UNIX

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This is a TCP port redirector for UNIX. It can be run under inetd or as a standalone daemon (in which case it handles multiple connections). It is 8-bit clean, not limited to line mode, yet small and lightweight. If you want access control, run it under xinetd or inetd with TCP wrappers.

redir listens for TCP connections on a given SRC:PORT. When clients connect to redir it initiates a connection to the server on DST:PORT to pass data between them. The SRC and DST are from the perspective of redir.

                      -------> SRC:PORT -----> DST:PORT

Request:       CLIENT -------> redir --------> SERVER


Response:      CLIENT <------- redir <-------- SERVER
                                     --bind=addr

Note: the --bind=ADDR argument is to limit redir on the server side reply, in case the box redir runs on have multiple addresses or interfaces on the server side.

redir finds most of its applications in traversing firewalls, but, of course, there are other use-cases. For a UDP port redirector, see uredir

Usage

Consult the man page for details.

Usage: redir [-hinspv] [-b IP]  [-f TYPE] [-I NAME] [-l LEVEL] [-t SEC]
                       [-x STR] [-m BPS] [-o FLAG] [-w MSEC] [-z BYTES]
                       [SRC]:PORT [DST]:PORT
Options:
  -b, --bind=IP            Listen only to IP on the server-side connection,
                           how DST connects to redir. Not applicable with -p
  -f, --ftp=TYPE           Redirect FTP connections.  Where type is
                           one of: 'port', 'pasv', or 'both'
  -h, --help               Show this help text
  -i, --inetd              Run from inetd, SRC:PORT comes from stdin
                           Usage: redir [OPTIONS] [DST]:PORT
  -I, --ident=NAME         Identity, tag syslog messages with NAME
                           Also used as service name for TCP wrappers
  -l, --loglevel=LEVEL     Set log level: none, err, notice*, info, debug
  -n, --foreground         Run in foreground, do not detach from terminal
  -p, --transproxy         Run in Linux's transparent proxy mode
  -s, --syslog             Log messages to syslog
  -t, --timeout=SEC        Set timeout to SEC seconds, default off (0)
  -v, --version            Show program version
  -x, --connect=STR        CONNECT string passed to proxy server

Traffic Shaping:
  -m, --max-bandwidth=BPS  Limit the bandwidth to BPS bits/second
  -o, --wait-in-out=FLAG   Wait for in(1), out(2), or in&out(3)
  -w, --random-wait=MSEC   Wait MSEC milliseconds before each packet
  -z, --bufsize=BYTES      Size of the traffic shaping buffer

SRC and DST are optional, redir will revert to use 0.0.0.0 (ANY)

Old Syntax

Command line options changed in v3.0. A limited subset of the old syntax is available with the --enable-compat configure option. This implicitly also enables -n by default.

The following subset of the old syntax are available:

  --lport=PORT             Local port (when not running from inetd)
  --laddr=ADDRESS          Local address (when not running from inetd)
  --cport=PORT             Remote port to redirect traffic to
  --caddr=ADDRESS          Remote address to redirect traffic to

Examples

To redirect port 80 to a webserver listening on loopback port 8080, remember to use sudo when using priviliged ports:

sudo redir :80 127.0.0.1:8080

This starts redir as a standard UNIX daemon in the background, with all log messages sent to the syslog. Use -n to foreground and see log messages on stderr.

To run redir from a process monitor like Finit or systemd, tell it to not background itself and to only use the syslog for log messages:

redir -n -s :80 127.0.0.1:8080

An /etc/inetd.conf line of the same looks very similar:

http  stream  tcp  nowait  root  /usr/sbin/tcpd /usr/bin/redir -n -s -i 127.0.0.1:8080

When running multiple redir instances it can be useful to change how they identify themselves:

redir -I nntp www:119 netgate:119
redir -I pop3 ftp:110 netgate:110

This starts an NNTP and a POP3 port redirector, named accordingly. Previously therere was a redir-wrapper script included in the distribution, but that is no longer maintained.

Building

Redir comes with a GNU configure script which you can use to adapt the build to your needs. If you would like to remove support for some extended options (for the sake of speed, code size, whatever), try the following options to configure:

--enable-compat    Enable limited v2.x command line syntax
--disable-shaper   Disable traffic shaping code
--disable-ftp      Disable FTP redirection support

The GNU Configure & Build system use /usr/local as the default install prefix. For most use-cases this is fine, but if you want to change this to /usr use the --prefix=/usr configure option:

./configure --prefix=/usr
make -j5
sudo make install-strip

Building from GIT sources require you have automake and autoconf installed. Use ./autogen.sh to create the configure script.

Origin & References

Redir was originally created by Nigel Metheringham and Sam Creasey. It is now maintained at GitHub by Joachim Wiberg. Use GitHub to file bug reports, clone, or send pull requests for bug fixes and extensions.

Redir is distributed under the terms of the GNU Public Licence, version 2 or later, distributed with this source archive in the file COPYING.