Check open ports

TCP listening ports with PID and process name (modern netstat)

ss -tlnp

More linux commands

Find process by port

ss -tlnp | grep :<port>

Which process is listening on a specific port
CPU usage per process

ps aux --sort=-%cpu | head -15

Top 15 processes by CPU consumption
Memory usage per process

ps aux --sort=-%mem | head -15

Top 15 processes by memory consumption
Follow systemd service logs

journalctl -u <service> -f --since '10 minutes ago'

Stream logs for a systemd unit from the last 10 minutes
Check systemd service status

systemctl status <service> --no-pager -l

Service status, recent log lines, and active timers