Reverse tunnel. Connect to a public host somewhere and have it redirect all connections to your machine behind a NAT or firewall

gistfile1.sh

# This enables a publicly available server to forward connections to your computer behind a NAT.
# So if you access http://xx.xx.xx.xx:8080/ on your browser, traffic is redirected to your machine behind a NAT.

# on your local host, type:
ssh -R xx.xx.xx.xx:8888:localhost:80 root@xx.xx.xx.xx

# now wait for your shell, and type:
socat TCP-LISTEN:8080,FORK TCP:127.0.0.1:8888

# This command outputs nothing, just keep it running. While you don't ^C, your tunnel is up and running!

# Address already in use? Change the ports you're using.
# Wanna change the ports? Read this.
# 80 is the port I want to access on my own machine which is behind a NAT
# 8080 is a port that the public server listens on. So if I access http://my-public-server:8880, I actually get to my own machine.
# xx.xx.xx.xx is the IP address of my server. I think you could use a hostname for this.
# 8888 is the port for the reverse tunnel. SSH will listen when my-public-server tries to access it, and forward connections to port 80 on my machine behind NAT.

Great. Works perfectly.

For Address already in use errors, you can use SO_REUSEADDR. (In the following example, I use TCP4, but it should work with TCP).

socat TCP4-LISTEN: 8080,FORK,REUSEADDR TCP4:127.0.0.1:8888

good !