Introduction of Ubuntu Server Construction

Show a list of correspondence between used port numbers and servers --lsof -i TCP -P

To see a list of correspondences between used port numbers and servers, use the lsof command and specify the following options:

lsof -i TCP -P

The "-i" option is limited to TCP only. Practically, if you can see only TCP, there is no duplication and it is easy to see. With the "-P" option, the port is displayed without displaying the protocol (http, etc.).

This is a sample output result of lsof.

rpcbind 891 root 8u IPv4 29717 0t0 TCP *: 111 (LISTEN)
rpcbind 891 root 11u IPv6 29720 0t0 TCP *: 111 (LISTEN)
systemd-r 1022 systemd-resolve 13u IPv4 31385 0t0 TCP localhost: 53 (LISTEN)
vsftpd 1439 root 3u IPv6 36168 0t0 TCP *: 21 (LISTEN)
redis-ser 1466 redis 6u IPv4 36518 0t0 TCP localhost: 6379 (LISTEN)
redis-ser 1466 redis 7u IPv6 36520 0t0 TCP ip6-localhost: 6379 (LISTEN)
mysqld 1622 mysql 17u IPv4 39040 0t0 TCP localhost: 3306 (LISTEN)
master 1806 root 13u IPv4 38037 0t0 TCP localhost: 25 (LISTEN)
master 1806 root 14u IPv6 38038 0t0 TCP ip6-localhost: 25 (LISTEN)
postgres 1869 postgres 7u IPv4 38483 0t0 TCP localhost: 5432 (LISTEN)
rpc.mount 41471 root 9u IPv4 16631878 0t0 TCP *: 45357 (LISTEN)
rpc.mount 41471 root 11u IPv6 16631884 0t0 TCP *: 34119 (LISTEN)
rpc.mount 41471 root 13u IPv4 16631890 0t0 TCP *: 59105 (LISTEN)
rpc.mount 41471 root 15u IPv6 16631898 0t0 TCP *: 43515 (LISTEN)
rpc.mount 41471 root 17u IPv4 16631904 0t0 TCP *: 49259 (LISTEN)
rpc.mount 41471 root 19u IPv6 16631910 0t0 TCP *: 56847 (LISTEN)
apache2 52756 root 4u IPv6 5714981 0t0 TCP *: 80 (LISTEN)
apache2 52756 root 6u IPv6 5714985 0t0 TCP *: 443 (LISTEN)
sshd 79341 root 3u IPv4 58345111 0t0 TCP *: 55555 (LISTEN)
sshd 79341 root 4u IPv6 58345113 0t0 TCP *: 55555 (LISTEN)
apache2 109162 www-data 4u IPv6 5714981 0t0 TCP *: 80 (LISTEN)
apache2 109162 www-data 6u IPv6 5714985 0t0 TCP *: 443 (LISTEN)
apache2 109163 www-data 4u IPv6 5714981 0t0 TCP *: 80 (LISTEN)
apache2 109163 www-data 6u IPv6 5714985 0t0 TCP *: 443 (LISTEN)
apache2 109164 www-data 4u IPv6 5714981 0t0 TCP *: 80 (LISTEN)
apache2 109164 www-data 6u IPv6 5714985 0t0 TCP *: 443 (LISTEN)
apache2 109165 www-data 4u IPv6 5714981 0t0 TCP *: 80 (LISTEN)
apache2 109165 www-data 6u IPv6 5714985 0t0 TCP *: 443 (LISTEN)
apache2 109166 www-data 4u IPv6 5714981 0t0 TCP *: 80 (LISTEN)
apache2 109166 www-data 6u IPv6 5714985 0t0 TCP *: 443 (LISTEN)
apache2 111526 www-data 4u IPv6 5714981 0t0 TCP *: 80 (LISTEN)
apache2 111526 www-data 6u IPv6 5714985 0t0 TCP *: 443 (LISTEN)
apache2 113400 www-data 4u IPv6 5714981 0t0 TCP *: 80 (LISTEN)
apache2 113400 www-data 6u IPv6 5714985 0t0 TCP *: 443 (LISTEN)