mcudpt

README

mcudpt

Multi-Client UDP Tunnel

Mcudpt is a small program written in Go (Go-lang) designed to mimic the functionality of ssh -R for UDP packets, in tunneling UDP packets over a TCP connection.

Note: this mimicing does not include encryption: the UDP packets are tunnled over an unencrypted TCP connection. If you wish to have encryption, use this on top of a ssh TCP tunnel.

Install

This requires the Go (go-lang) dev tools and a properly setup go workspace (http://golang.org/doc/code.html)

Just execute 'go get github.com/SamLex/mcudpt'. This will create a mcudpt binary in your workspaces bin directory

Usage

The program is split into two components: the receiver and the sender. The receiver listens for incoming UDP packets and sends them to the connected sender over TCP. The sender connects to the receiver and sends any UDP packets it is sent by the receiver to the address given.

Below is an example for forwarding DNS requests.

Receiver:

Set receiver to listen on port 53 for UDP connections and port 5353 for TCP connections

./mcudpt -mode receiver -udp :53 -tcp :5353

Receiver now listens for TCP connection from sender

Sender:

Set sender to connect to tunnel-server (setup above) on TCP port 5353 and send UDP packets to internal-dns.lan:53

./mcudpt -mode sender -udp internal-dns.lan:53 -tcp tunnel-server:5353

Now any DNS requests made to tunnel-server on port 53, will be tunneled to internal-dns port 53 and the reply sent back to the correct address

Security Note

Before the receiever accepts any messages from the sender it asks for user verification that it is the right sender. This is due to the fact that a malicious sender could use a receiver as a DDOS masker/amplifier. Once one sender has been accepted, however, no more can connect so only one verification is required.

Resource Note

Because of the way this program and the UDP protocol are designed, the UDP sockets opened by the sender are never closed during execution so during long-running exececutions or high-traffic situations, an occasional restart is advised to clear the open UDP sockets. This problem may be fixed in the future.

Documentation

Overview

Copyright (c) 2014, SamLex (Euan James Hunter) All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

• Neither the name of mcudpt nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.