No linux moderno, use o utilitário ss (estatísticas de soquete).
$ ss -s
Total: 10160 (kernel 10262)
TCP: 10349 (estab 8886, closed 408, orphaned 0, synrecv 0, timewait 393/0), ports 3147
Transport Total IP IPv6
* 10262 - -
RAW 0 0 0
UDP 5 5 0
TCP 9941 9941 0
INET 9946 9946 0
FRAG 0 0 0