Socat

Forward port 80 to localhost:8090

• socat TCP-LISTEN:80,fork TCP:127.0.0.1:8090
• socat TCP-LISTEN:80,fork,reuseaddr TCP:127.0.0.1:8090

Debugging:

• socat -d -d TCP-LISTEN:80,fork TCP:127.0.0.1:8090

Logs opens connections:

2019/05/13 04:24:30 socat[15433] N listening on AF=2 0.0.0.0:XX
2019/05/13 04:24:43 socat[15433] N accepting connection from AF=2 xx.99.12.xxx:62833 on AF=2 xxx.xxx.xxx.xxx:2244
2019/05/13 04:24:43 socat[15433] N forked off child process 15438
2019/05/13 04:24:43 socat[15433] N listening on AF=2 0.0.0.0:XX
2019/05/13 04:24:43 socat[15438] N opening connection to AF=2 1xx.253.51.xx:XX
2019/05/13 04:24:44 socat[15438] N successfully connected from local address AF=2 xxx.xxx.xxx.xxx:46596
2019/05/13 04:24:44 socat[15438] N starting data transfer loop with FDs [6,6] and [5,5]

See also

• telnet, netcat, nc, nc -l, ncat, socat, ngrok
• Ports, sftp

https://unix.stackexchange.com/a/293308