lsof -i TCP| fgrep LISTEN

netstat -lntu

ss -lntu

netstat -lntu

-n, --numeric       don't resolve service names
-l, --listening     display listening sockets
-t, --tcp           display only TCP sockets
-u, --udp           display only UDP sockets

netstat -tuwanp 2>/dev/null | awk '{print $4}' | sort | uniq -c | wc -l

netstat -lnt | awk 'NR>2{print $4}' | grep -E '0.0.0.0:' | sed 's/.*://' | sort -n | uniq

netstat -lnt | awk 'NR>2{print $4}' | grep -E ':::' | sed 's/.*://' | sort -n | uniq

netstat -lnt | awk 'NR>2{print $4}' | grep -E '(0.0.0.0:|:::)' | sed 's/.*://' | sort -n | uniq

netstat -lnt | awk 'NR>2{print $4}' | grep -E '(127.0.0.1:|::1:)' | sed 's/.*://' | sort -n | uniq