OpenSSH provides the ability to hash the known_host file using salted SHA.
Because of how IPv4, IPv6 and host names are created, this tool is able to
attack the following vectors:

1.	Limited char-sets
2.	known plain-text

Description related to:

	a) IPv4 
		A typical IPv4 address consists of four numbers between 0-255
		separated by a dot. Furthermore no IPv4 address can start with a
		dot and it is very likely that private/reserved IP spaces might
		not be used for hosts at the Internet.

		The complexity is below 2^32

	b) IPv6
		IPv6 is hexadecimal and provides a bigger address size.
		Except this everything works like for IPv4.

	c) Host-names
		Host-names have similar rules for their naming scheme than
		IP addresses. But because the char-set is bigger the complexity
		raises. It is known that OpenSSH converts every host-name
		to lowercase which reduces the complexity a lot.
		Except this it is believed that attacking the known_host file
		via the IPs is the faster and more efficient way.
		OpenSSH stores the host-name AND the IP for a given host-name.
		This might not be true for IPv6 at all but you can, in case you
		guessed a valid IPv6 address and the reverse look-up provides
		you the host-name, brute force host-names based upon that
		information.
