# netstat -luntp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address  State   PID/Program name
tcp        0      0 0.0.0.0:22    0.0.0.0:*        LISTEN  1679/sshd
udp        0      0 0.0.0.0:68    0.0.0.0:*                1766/dhclient
-------------------------
# netstat -a -n | egrep 'Proto|LISTEN'
Proto Recv-Q Send-Q  Local Address          Foreign Address        (state)
tcp4       0      0  *.587                  *.*                    LISTEN
tcp4       0      0  *.25                   *.*                    LISTEN
tcp4       0      0  *.22                   *.*                    LISTEN
tcp4       0      0  *.993                  *.*                    LISTEN
tcp4       0      0  *.143                  *.*                    LISTEN
tcp4       0      0  *.53                   *.*                    LISTEN
-------------------------
# grep -w 993 /etc/services
imaps           993/udp     # imap4 protocol over TLS/SSL
imaps           993/tcp     # imap4 protocol over TLS/SSL
-------------------------
# sockstat -4 -l
USER     COMMAND    PID   FD PROTO  LOCAL ADDRESS        FOREIGN ADDRESS   
root     sendmail  1141    4 tcp4   *:25                 *:*
root     sendmail  1141    5 tcp4   *:587                *:*
root     sshd      1138    3 tcp4   *:22                 *:*
root     inetd     1133    4 tcp4   *:143                *:*
root     inetd     1133    5 tcp4   *:993                *:*
named    named     1127   20 tcp4   *:53                 *:*
named    named     1127   21 udp4   *:53                 *:*
named    named     1127   22 udp4   *:1351               *:*
-------------------------
# lsof -i -n | egrep 'COMMAND|LISTEN'
COMMAND   PID   USER FD  TYPE     DEVICE SIZE/OFF NODE NAME
named    1127 named  20u IPv4 0xeb401dc0      0t0  TCP *:domain (LISTEN)
inetd    1133  root   4u IPv4 0xeb401ba0      0t0  TCP *:imap (LISTEN)
inetd    1133  root   5u IPv4 0xeb401980      0t0  TCP *:imaps (LISTEN)
sshd     1138  root   3u IPv4 0xeb401760      0t0  TCP *:ssh (LISTEN)
sendmail 1141  root   4u IPv4 0xeb41b7e0      0t0  TCP *:smtp (LISTEN)
sendmail 1141  root   5u IPv4 0xeb438fa0      0t0  TCP *:submission (LISTEN)
