$ gcc server.c -o server

$ gcc client.c -o client

$ ./server &
[1] 6422

$ netstat -ant
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:6010          0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:6011          0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:3306          0.0.0.0:*               LISTEN
tcp        0    216 192.168.56.2:22         192.168.56.1:54688      ESTABLISHED
tcp        0      0 192.168.56.2:22         192.168.56.1:59121      ESTABLISHED
tcp6       0      0 :::22                   :::*                    LISTEN
tcp6       0      0 ::1:6010                :::*                    LISTEN
tcp6       0      0 ::1:6011                :::*                    LISTEN
tcp6       0      0 :::5000                 :::*                    LISTEN

$ ./client
hoge
fuga
piyo