BG/L compute node supports BSD style socket partly, not completely. You can't use the server side functions.
I provide a concrete example of BG/L socket programming. Actually it's nothing special but it may be convenient for a quick test.
First of all, download cnk-socket.tgz, extract and make it.
Then start a receiver(server) program on the BG/L front end machine.
$ ./simple_tcp_server 9876
Then submit a sender(client) program with the cqsub command (for ANL user). The command like would be something like
$ cqsub -q short -c 16 -n 64 -t 5 ./tcp_client_mpi 172.30.1.102
Once your submitted job starts, the simple_tcp_server program prints recevied message to stdout.
NOTE: 172.30.1.102 is the IP address of the login node where
simple_tcp_server is running. The login node has probably two or more
IP address. You may need to figure out which IP address is for BG/L
Nodes. In other words, the IP address you are looking for is not IP
address you used to login.
The ifconfig command may help you finding all IP addresses on the login node. $SSH_CONNECTION may tell you which IP address you used to login.
$ make all bglcnktcp-ciodwill generate NPtcp and bglcnktcp-ciod, server program and receiver program respectively.
If you have an environment for zoid, try
$ make all bglcnktcp-zoid