fcnatfw

standalone NAT traversal / automatic port forwarding tool.

components:

• bin/fcnatfw - attempts to create and maintains a globally accessible port mapping using repeated STUN pings and UPnP, prints external address on stdout
• bin/fcnatwrap - overloads C library socket functions to force SO_REUSEPORT

usage example

step -1: install ping, stunclient from stuntman, miniupnpc, nmap's ncat
step 0. compile the evil shared library in lib/ using lib/build.sh (after cd'ing into lib)
step 1. forward port 1234: fcnatfw 1234 tcp (keep this running)
step 2. run ncat under fcnatwrap so it can share the port with fcnatfw: fcnatwrap ncat -k -l -c 'echo Meow!' 1234
step 3. share ip:port printed by fcnatfw with others to connect

this only works if all NATs in your path either are Full Cone, or support UPnP port forwarding.