$ netstat -anp --numeric-ports | grep ":80\>.*:" 
tcp6       0      0 :::80           :::*            LISTEN      1914/apache2    

$ fuser -v "80/tcp"
                     USER        PID ACCESS COMMAND
80/tcp:              root       1914 F.... apache2
                     www-data  12418 F.... apache2
...

$ lsof -P -S 2 -i "tcp:80" | grep "\(:80->.*:\|:80 (LISTEN)$\)"
apache2  1914     root    4u  IPv6   11920      0t0  TCP *:80 (LISTEN)
apache2 12418 www-data    4u  IPv6   11920      0t0  TCP *:80 (LISTEN)
...