GUT stands for Generic UDP Tunneling that can be used to deploy new transport protocols on the end-host without configuration of firewall and NAT devices.
The basic idea of GUT is to encapsulate the native transport protocol and its payload (in general the whole IP payload) within a UDP packet destined to the well-known port GUT_P.
Currently this implemenataion is a prototype of GUT, supports UDP ,ICMP ,DCCP and TCP tunneling.
Installation is pretty straight forward, just do "make" for compiling.

To tunnel traffic between two end-hosts, we need to run GUT service on both hosts and have root access. The following command line options can be used for GUT:

-a addr		Set TUN Interface IPV4 Address
-d port		Set GUT_P (deault 4887)
-i prefix	Set TUN Interface prefix name (default tun)
-m mark_id	Set iptables OUTGOING chain rule mark id (default 3)
-o string	Add iptables OUTGOING chain rule match options
-r table_id	Set TUN routing table id (default 203)
-t path		Set full path to iptables executable (default /sbin/iptables)

Example:

1. Tunnel ICMP Echo Request and Reply traffic between two end-hosts: 

on the ping side, specify TUN interface IP address with -a option, for example 10.0.0.1, specify tunneling traffic to ICMP Echo Request packet with -o option:
gut -a 10.0.0.1 -o “-p icmp --icmp-type 8”

on the pong side specify TUN interface IP address, for example 10.0.0.1 
gut -a 10.0.0.1

2. Tunnel TCP to port 9999: "-p tcp --dport 9999"

3. Tunnel TCP with TCP option 88: "-p tcp --tcp-option 88"

4. Tunnel DCCP: "-p 33" (may need also "-m dccp")