I think you first have to look through the open fds in /proc/*/fd, e.g.
4 -> socket:[11147]
and then look for the referenced sockets (by the inode) in /proc/net/tcp (or /proc/net/udp), e.g.
12: B382595D:8B40 D5C43B45:0050 01 00000000:00000000 00:00000000 00000000 1000 0 11065 1 ffff88008bd35480 69 4 12 4 -1