CmdID / Commands
Port knocking client to open specific ports on firewall. tldr-pages
On Linux
Opens CmdID with your command. It is read in your browser and sent nowhere.
Knock on ports using different protocols
knock hostname portnumber:protocol
Knock on port using UDP
knock --udp hostname portnumber
Force usage of IPv4/IPv6
knock -4 hostname portnumber
Display errors and details of connection
knock --verbose hostname portnumber