remote peer will be connected through. This avoids the ``Checking for
invitation on caller's machine'' problem for multi-homed hosts.
Thanks to: Garrett, for his `find_interface' example
aa.bb aa:bb and aa!bb treated as user+host and not as local user
names (especially aa.bb is common case).
Only @ is valid user/host separator according to manpage.
Pointed-by: doctor@dream.demos.su