#ports
4 one-liners with this tag.
All one-liners tagged ports
Check server ports from outside with nmap
$nmap -Pn -p 21,22,25,80,110,143,443,465,587,993,995,3306,8443,8880 server.example.com
List open ports and listening services
#ss -tulpn
Show the published ports of a Docker container
#docker port app
Test if a TCP port is reachable without telnet or nc
$timeout 3 bash -c '</dev/tcp/db.example.com/3306' && echo offen || echo "geschlossen oder gefiltert"