I’m using socat to forward traffic from a local port to a remote server over SSL. My command is as follows:
socat -d -d TCP-LISTEN:1234,fork,reuseaddr OPENSSL:192.168.1.2:1234,verify=0
However, I’m experiencing an issue where the child processes created by socat are not terminating even after the client disconnects. When I close the client connection (using nc localhost 1234 to establish the connection and then press ctrl-C), I see the following in the socat debug log:
2024/07/06 22:37:12 socat[146196] N listening on AF=10 [0000:0000:0000:0000:0000:0000:0000:0000]:1234
2024/07/06 22:37:14 socat[146196] N accepting connection from AF=10 [0000:0000:0000:0000:0000:ffff:7f00:0001]:41648 on AF=10 [0000:0000:0000:0000:0000:ffff:7f00:0001]:1234
2024/07/06 22:37:14 socat[146196] N forked off child process 146210
2024/07/06 22:37:14 socat[146196] N listening on AF=10 [0000:0000:0000:0000:0000:0000:0000:0000]:1234
Despite this, the child processes remain active. Here is a pgrep -a socat output of hanging processes:
146196 socat -d -d TCP-LISTEN:1234,fork,reuseaddr OPENSSL:192.168.1.2:1234,verify=0
146210 socat -d -d TCP-LISTEN:1234,fork,reuseaddr OPENSSL:192.168.1.2:1234,verify=0
What I’ve Tried:
- Adding
keepaliveand it’s settings options (based on this question): No improvement. -tand-Tparameters: No improvement.
Observations:
- when I let the client end the session properly, the child process on the socat side shuts down properly
- by default, ten seconds after the client sends the EOF, socat prints this to logs:
N inactivity timeout triggered
N exiting with status 0
but the child process is still active.
I create many forked connections and over time the server creates hundreds of hanging processes that allocate hundreds of megabytes of memory until the server crashes.
Any help or suggestions would be greatly appreciated!