Check Linux Listening Ports

linux port security network

ss comand

sudo ss -ltu
sudo ss -ltup  #show process

netstat command

sudo netstat -l
sudo netstat -tulpn | grep LISTEN

Check active connections (-t TCP, -u UDP, -n Show IP)

sudo netstat -vantu  # show ip
sudo netstat -vant   # show FQDN
sudo netstat -vant   # TCP only

lsof command

sudo lsof -i
sudo lsof -i -P -n | grep LISTEN
sudo lsof -i 4 -a

nmap command

sudo nmap -sT -O localhost
sudo nmap -sU -O 192.168.1.20 ## list open UDP ports
sudo nmap -sT -O 192.168.1.20 ## list open TCP ports

Written on November 3, 2017