tgcd


 

Index

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
SEE ALSO
AVAILABILITY
COPYRIGHT AND LEGAL ISSUES
AUTHOR
DOWNLOAD
RELATED WROKS

 

NAME

tgcd - TCP/IP Gender Changer Daemon utility  

SYNOPSIS

tgcd -C -s<host:port> -c<host:port> [-i<n>] [-k<n>] [<common options>]
tgcd -L -p<port> -q<port> [-k<n>] [<common options>]
tgcd -F -p<port> -s<host:port> [<common options>]  

DESCRIPTION

tgcd is a simple Unix network utility to extend the accessibility of TCP/IP based network services beyond firewalls. This can also be used by network analysts and security experts for penetration testing and analyze the security of their network. It has three different modes:

- ConnectConnect (or CC, specified by option -C)
- ListenListen (or LL, specified by option -L)
- Port Forwarder (or PF, specified by option -F)

The ConnectConnect and ListenListen instances of tgcd are used jointly together, while the Port Forwarder mode acts standalone. The ConnectConnect instance resides somewhere on the network (inside the LAN) where it can access the desired server, while the ListenListen will be where the external client can access it (outside the LAN). The ConnectConnect instance, when started, tries to establish a control connection to ListenListen instance (if failed it will retry every n seconds specified by -i ). The ListenListen instance upon receiving a connection from client, will send a request to ConnectConnect (over the already established control connection) to establish a connection to server as well as another connection to ListenListen for data transferring. In the Port Forwarder mode, tgcd will pump data from one port to another providing a basic port forwarding functionality.

For all three modes, one can choose (using -m option) between two different ways of handling multiple connections. By choosing the Select method, the program will use less system memory in expense of slower handling of multiple connections, and on the other side by choosing Fork method tgcd will handle the multiple connections faster in expense of system memory.

tgcd links with libwrap (if available at build time) to provide a simple access control mechanism that's provided by hosts_access(5).

 

OPTIONS

-C, --ccnode
Become a CC (ConnectConnect) node.
-s, --server <host:port>
The host and port of the actual server
-c, --llhost <host:port>
The host and port of the ListenListen node.
-i, --interval <seconds>
Time interval to periodically report to LL (default: 40s).
-k, --key <number>
poorman's encryption (0-255, default: 0, means no encryption)

Options for ListenListen mode:
-L, --llnode
Become a LL (ListenListen) node.
-q, --llport number
The port to listen on for incoming connection from a CC node
-p, --port number
The port to listen of for incoming actual client connection
-k, --key number
poorman's encryption (0-255, default: 0, means no encryption)
Port forwarder options:
-F, --lcnode
Become a ListenConnect node, i.e. just a simple port forwarder
-p, --port number
The port to listen of for incoming actual client connection
-s, --server host:port
The host and port of the destination server
Common options:
-m, --method {f|s}
f: Fork s: Select (default: s)
-l, --log file
Write logs to file. (default:'/dev/null')
-g, --level number
Log level detail (default:0).
-n, --nodaemon
Do not become daemon
-h, --help
Display this.
-v, --version
Display version number.

 

EXAMPLES

Lets say you'd like to access a localy running WEB server on your work PC from home, this is how to do it:

To run tgcd in CC mode and provide access to the local WEB server :


tgcd -C -s localhost:80 -c my_home_computer:1234


To run tgcd in LL mode on my_home_computer host to provide access to the above service:


tgcd -L -p 8000 -q 1234


This will make the WEB server running on the work PC accessible on port 8000 of my_home_computer.

 

SEE ALSO

hosts_access(5)  

AVAILABILITY

tgcd is tested on Linux 2.2.x (x86), 2.4.x (x86), 2.6.x (x86, ARM9, AVR32), Cygwin (1.5.x), and NetBSD 2.1.0
Please feel free to send us your patches to get tgc working on other platforms.

 

COPYRIGHT AND LEGAL ISSUES

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. Disclaimer:

This program is provided with no warranty of any kind, either expressed or implied. It is the responsibility of the user (you) to fully research and comprehend the usage of this program. As with any tool, it can be misused, either intentionally or unintentionally. THE AUTHOR(S) IS(ARE) NOT RESPONSIBLE FOR ANYTHING YOU DO WITH THIS PROGRAM or anything that happens because of your use (or misuse) of this program. THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.  

AUTHOR

tgcd is written by Faraz.V (farazv _AT_ users.sourceforge.net)

 

DOWNLOAd

tgcd can be downloaded from here

 

RELATED WORKS

The idea is nothing new and there has been many implementation of it available already, namely:

- Revinetd, available at: http://revinetd.sourceforge.net
- An implementation using "socat", http://www.dest-unreach.org/socat/doc/socat-gender.txt
- FireWall Tunnel, available at: http://sourceforge.net/projects/firewall-tunnel/
- An artile explaining the idea
There also might be other implementations using netcat or other network utilities.


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This document was created by man2html using the manual pages.
Time: 18:08:45 GMT, December 04, 2008