lsof is a linux command to list open files.
To list all files open by a process, run
lsof -p PID
Example
boby@hon-pc-01:~ $ lsof -p 10132 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME tail 10132 boby cwd DIR 8,19 4096 2098166 /home/boby/www tail 10132 boby rtd DIR 8,18 4096 2 / tail 10132 boby txt REG 8,18 64432 4720044 /usr/bin/tail tail 10132 boby mem REG 8,18 2981280 4731729 /usr/lib/locale/locale-archive tail 10132 boby mem REG 8,18 1864888 3801314 /lib/x86_64-linux-gnu/libc-2.23.so tail 10132 boby mem REG 8,18 162632 3801316 /lib/x86_64-linux-gnu/ld-2.23.so tail 10132 boby 0u CHR 136,13 0t0 16 /dev/pts/13 tail 10132 boby 1u CHR 136,13 0t0 16 /dev/pts/13 tail 10132 boby 2u CHR 136,13 0t0 16 /dev/pts/13 tail 10132 boby 3r REG 8,18 262941 4194568 /var/log/syslog tail 10132 boby 4r a_inode 0,11 0 8136 inotify boby@hon-pc-01:~ $
List all Connection on a Port
root@hon-vpn:~# lsof -i :80 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME apache2 6811 www-data 4u IPv6 25414114 0t0 TCP *:http (LISTEN) apache2 11035 www-data 4u IPv6 25414114 0t0 TCP *:http (LISTEN) apache2 11036 www-data 4u IPv6 25414114 0t0 TCP *:http (LISTEN) apache2 11037 www-data 4u IPv6 25414114 0t0 TCP *:http (LISTEN) apache2 11038 www-data 4u IPv6 25414114 0t0 TCP *:http (LISTEN) apache2 11039 www-data 4u IPv6 25414114 0t0 TCP *:http (LISTEN) apache2 25240 root 4u IPv6 25414114 0t0 TCP *:http (LISTEN) root@hon-vpn:~#
lsof -P -iTCP
List all TCP connections
root@hon-vpn:~# lsof -P -iTCP COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME sshd 392 root 3u IPv4 10961 0t0 TCP *:3333 (LISTEN) sshd 392 root 4u IPv6 10970 0t0 TCP *:3333 (LISTEN) prometheu 394 root 21u IPv6 12232 0t0 TCP *:9090 (LISTEN) xinetd 6687 root 5u IPv4 6405498 0t0 TCP *:5666 (LISTEN) pure-ftpd 6750 root 4u IPv4 6405818 0t0 TCP *:21 (LISTEN) pure-ftpd 6750 root 5u IPv6 6405819 0t0 TCP *:21 (LISTEN) apache2 6811 www-data 4u IPv6 25414114 0t0 TCP *:80 (LISTEN) sshd 8551 root 3u IPv4 1148099283 0t0 TCP vpn.hostonnet.com:3333->59.98.136.47:38238 (ESTABLISHED) apache2 11035 www-data 4u IPv6 25414114 0t0 TCP *:80 (LISTEN) apache2 11036 www-data 4u IPv6 25414114 0t0 TCP *:80 (LISTEN) apache2 11037 www-data 4u IPv6 25414114 0t0 TCP *:80 (LISTEN) apache2 11038 www-data 4u IPv6 25414114 0t0 TCP *:80 (LISTEN) apache2 11039 www-data 4u IPv6 25414114 0t0 TCP *:80 (LISTEN) mysqld 16429 mysql 24u IPv6 25405306 0t0 TCP *:3306 (LISTEN) grafana-s 20491 root 5u IPv6 16802620 0t0 TCP *:3000 (LISTEN) grafana-s 20491 root 7u IPv4 1148149055 0t0 TCP vpn.hostonnet.com:38987->220.222.178.107.bc.googleusercontent.com:443 (ESTABLISHED) grafana-s 20491 root 9u IPv4 1148149428 0t0 TCP vpn.hostonnet.com:47816->151.101.0.133:443 (ESTABLISHED) squid3 20833 proxy 9u IPv6 27325704 0t0 TCP *:3128 (LISTEN) apache2 25240 root 4u IPv6 25414114 0t0 TCP *:80 (LISTEN) root@hon-vpn:~#
