nmap

Nmap is a utility for network exploration or security auditing. It
supports ping scanning (determine which hosts are up), many port
scanning techniques, version detection (determine service protocols
and application versions listening behind ports), and TCP/IP
fingerprinting (remote host OS or device identification). Nmap also
offers flexible target and port specification, decoy/stealth scanning,
sunRPC scanning, and more. Most Unix and Windows platforms are
supported in both GUI and commandline modes.

Once installed, this snap needs manually connecting to some plugs:

sudo snap connect nmap:network-control

Main website: https://nmap.org/