SSH from host to jail

I'm trying to set up some jails in a 5.1R system.  I've pretty much
copied a setup that was working fine in 4.8; but on 5.1 I can't seem
to SSH from the host system into one of its jails.  It acts like the
packets just aren't getting through.

I would really appreciate it if somebody would send me rc.conf fragments
that are known to work for setting up a jail's IP alias and routing on
5.1.



Thanks,
-Pat