Socat

wikipedia:socat (2009)

• http://www.dest-unreach.org/socat/
• Alpine: https://hub.docker.com/r/alpine/socat
• brew install socat
• socat -h

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 connections (-d -d):

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]

Errors

socat TCP-LISTEN:8043,fork TCP:10.10.10.xx:443
2020/08/10 19:24:54 socat[1587199] E bind(5, {AF=2 0.0.0.0:8043}, 16): Address already in use

socat TCP-LISTEN:192.168.10.1:80,fork TCP:127.0.0.1:8090
2021/02/07 11:43:49 socat[26463] E TCP-LISTEN: wrong number of parameters (2 instead of 1)

Options

• nodelay Turns off the Nagle algorithm for measuring the RTT (round trip time).

Related terms

• logger, systemd-cat
• Port forwarding
• Santiago Zanella-Beguelin and Microsoft Vulnerability Research

See also

• telnet, netcat, nc, nc -l, ncat, socat, ngrok
• socat, socat -h, websocat

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