Linux utility to have two TCP server sockets talk to each other

Question

I have two TCP servers and each expects a client connection, but I need to have them talk to each other. This is how the connection looks like:

DEVICE -> UART -> SER2NET -> XXX <- OFONO-PHONESIM

Ser2net listens on a port and ofono-phonesim listens on a port, but ultimately I want the device to speak to the modem simulator.

It would not be hard to implement the XXX, but perhaps there is something ready available? A suggestion of a simple suitable scripting language library would be appreciated as well.

Answer 1

socat.

If I understood your problem correctly, then I can simulate your environment with three terminals.

In the first, I run nc -l -p 1337. In the second, I run nc -l -p 1338.

Now, in the third, I run

socat "TCP4-CONNECT:127.0.0.1:1337" "TCP4-CONNECT:127.0.0.1:1338"

and I am able to enter text in terminal 1 and it arrives in terminal 2. And vice versa.