Require Multiple keys per host

[bob-openssh at technogeeks.com]

As of version 3.0.2p1 and perhaps earlier localhost forwarded connections
are checked in known_hosts.  The difficulty is that if you have multiple
forwards, only one of them will exist as a valid host key for localhost.
All the others will be treated as a "Changed" key prompting reduced
functionality including disallowing agent-forwarding.  Depending on
StrictHostKeyChecking being set, the connections might not be allowed at
all.

I suggest that the known host file have a host:port type scheme so a
machine running multiple sshd's will respond correctly as well as multiple
localforwards.

I note that this problem probably did not present itself since
KnownHostKey checkings did not seem to be active for localhost in older
versions of openssh.

Bob