Not knowing what port is used for what? No portblem.
Shows every listening TCP/UDP port, explains what it probably is, flags security oddities, and recommends a free port for your next dev server. Reads the local socket tables only — never sends packets.
go install github.com/kaxing/portwhat@latest
export PATH="$HOME/go/bin:$PATH"
portwhatportwhat overview + security notes + recommended next port
portwhat next print only the recommended port number (for scripts)
portwhat 3000 80 show status for specific ports
Some process names may show as unknown without elevated privileges.