Commonly Used TCP and UDP Ports

This document (7001745) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Desktop 10
SUSE Linux Enterprise Server 10

Situation

For network security, it is frequently needed to know on which port a particular daemon or service is listening.

Resolution

Most services or daemons that have their own PID (process identification) will simply show up in a 'netstat -nlptu' listing. However, services which start with xinetd will show up as xinetd listening on the port. As the Internet Engineering Task Force (IETF) manages these registered ports, identifying these services takes a little further investigation, but these are generally quickly identified by web searches. For specifics on the netstat command-line flags, please refer to the man pages.

Here is a list of commonly-used TCP and UDP ports. A similar list is generated by using the comand, 'netstat -planetu'.

Proto Local Address           Foreign Address         State       PID/Program name
tcp        0.0.0.0:21              0.0.0.0:*               LISTEN      11943/xinetd (ftp)
udp        0.0.0.0:67              0.0.0.0:*                           3857/dhcpd
udp        0.0.0.0:68              0.0.0.0:*                           10523/dhcpcd
udp        0.0.0.0:69              0.0.0.0:*                           11943/xinetd (tftp)
tcp        0.0.0.0:111             0.0.0.0:*               LISTEN      3390/portmap
udp        0.0.0.0:111             0.0.0.0:*                           3390/portmap
udp        0.0.0.0:137             0.0.0.0:*                           11021/nmbd
udp        0.0.0.0:138             0.0.0.0:*                           11021/nmbd
tcp        0.0.0.0:139             0.0.0.0:*               LISTEN      11046/smbd
tcp        0.0.0.0:143             0.0.0.0:*               LISTEN      11943/xinetd (imap)
tcp        0.0.0.0:389             0.0.0.0:*               LISTEN      6443/slapd
tcp        0.0.0.0:445             0.0.0.0:*               LISTEN      11046/smbd
tcp        0.0.0.0:631             0.0.0.0:*               LISTEN      3866/cupsd
udp        0.0.0.0:631             0.0.0.0:*                           3866/cupsd
udp        0.0.0.0:672             0.0.0.0:*                           8977/rpc.mountd
tcp        0.0.0.0:673             0.0.0.0:*               LISTEN      8977/rpc.mountd
udp        0.0.0.0:872             0.0.0.0:*                           10024/ypserv
tcp        0.0.0.0:873             0.0.0.0:*               LISTEN      11943/xinetd (rsync)
tcp        0.0.0.0:874             0.0.0.0:*               LISTEN      10024/ypserv
tcp        0.0.0.0:2049            0.0.0.0:*               LISTEN      - (nfs)
udp        0.0.0.0:2049            0.0.0.0:*                           - (nfs)
tcp        0.0.0.0:3205            0.0.0.0:*               LISTEN      5281/isnsd
tcp        0.0.0.0:3128            0.0.0.0:*               LISTEN      12836/(squid)
udp        0.0.0.0:3130            0.0.0.0:*                           12836/(squid)
tcp        0.0.0.0:3260            0.0.0.0:*               LISTEN      3346/ietd
udp        0.0.0.0:3401            0.0.0.0:*                           12836/(squid)
tcp        0.0.0.0:5801            0.0.0.0:*               LISTEN      11943/xinetd (vnc)
tcp        0.0.0.0:5901            0.0.0.0:*               LISTEN      11943/xinetd (vnc)
udp        0.0.0.0:32768           0.0.0.0:*                           3754/named
udp        0.0.0.0:32793           0.0.0.0:*                           12836/(squid)
tcp        127.0.0.1:25            0.0.0.0:*               LISTEN      6869/master
tcp        127.0.0.1:53            0.0.0.0:*               LISTEN      3754/named
udp        127.0.0.1:53            0.0.0.0:*                           3754/named
tcp        127.0.0.1:427           0.0.0.0:*               LISTEN      3830/slpd
tcp        127.0.0.1:953           0.0.0.0:*               LISTEN      3754/named
tcp        127.0.0.1:2544          0.0.0.0:*               LISTEN      3654/zmd
udp        127.0.0.2:3205          0.0.0.0:*                           5281/isnsd
udp        127.0.0.1:6005          0.0.0.0:*                           5281/isnsd
udp        127.0.0.1:6006          0.0.0.0:*                           5281/isnsd
tcp        192.168.0.128:53        0.0.0.0:*               LISTEN      3754/named
udp        192.168.0.128:53        0.0.0.0:*                           3754/named
udp        192.168.0.128:137       0.0.0.0:*                           11021/nmbd
udp        192.168.0.128:138       0.0.0.0:*                           11021/nmbd
tcp        192.168.0.128:427       0.0.0.0:*               LISTEN      3830/slpd
udp        192.168.0.128:427       0.0.0.0:*                           3830/slpd
udp        224.0.1.22:427          0.0.0.0:*                           3830/slpd
udp        239.255.255.253:427     0.0.0.0:*                           3830/slpd
udp        255.255.255.255:427     0.0.0.0:*                           3830/slpd
udp        255.255.255.255:3206    0.0.0.0:*                           5281/isnsd
tcp        :::22                   :::*                    LISTEN      3653/sshd
tcp        :::53                   :::*                    LISTEN      3754/named
udp        :::53                   :::*                                3754/named
tcp        :::80                   :::*                    LISTEN      4048/httpd2-prefork
udp        :::177                  :::*                                3652/gdm
tcp        :::389                  :::*                    LISTEN      6443/slapd
tcp        :::3260                 :::*                    LISTEN      3346/ietd
udp        :::32769                :::*                                3754/named
tcp        ::1:25                  :::*                    LISTEN      6869/master
tcp        ::1:953                 :::*                    LISTEN      3754/named

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