isakmpd.policy: how to parse the DN

[Andreas Schuldei <andreas_(_at_)_schuldei_(_dot_)_org>]

I encode the IP address of the vpn-gateways in their DNs of their certificates
request. 

As a peer I want to compare the certificate's DN (=the peer's IP) with the
remote_id_(what do I use here? ). I figure that would be quite save. 

However I do not know how I can tell isakmpd that is should compare the DN
with remote_id_(what_so_ever?) 

Please advise!