Utility to investigate sockets
ss -a {{-t/-u/-w/-x}}
ss -p
ss {{state/exclude}} {{bucket/big/connected/synchronized/...}}
ss -t dst 1.2.3.4:80
ss -u src 127/8
ss -t 'dport >= :1024'
ss -x "src /tmp/.X11-unix/*"
ss -t state established '( dport = :ssh or sport = :ssh )'
ss {{-4/-6}}