Tools for collecting host public keys
ssh-keyscan command is a tool for collecting a large number of host public keys.
ssh-keyscan(options)(parameters)
-4: Force the use of IPv4 addresses;
-6: Force the use of IPv6 addresses;
-f: Read "address list/name list" from the specified file;
-p: Specify the port to connect to the remote host;
-T: Specifies the timeout period for connection attempts;
-t: Specify the key type to be created;
-v: Information mode, print debugging information.
Host list: Specify the list of hosts from which public keys are to be collected.