-Specifies that in addition to public key authentication, the canonical name
-of the remote host must be present in the comma-separated list of
-patterns.
-The purpose
-of this option is to optionally increase security: public key authentication
-by itself does not trust the network or name servers or anything (but
-the key); however, if somebody somehow steals the key, the key
-permits an intruder to log in from anywhere in the world.
-This additional option makes using a stolen key more difficult (name
-servers and/or routers would have to be compromised in addition to
-just the key).
-.Pp
+Specifies that in addition to public key authentication, either the canonical
+name of the remote host or its IP address must be present in the
+comma-separated list of patterns.