ipsec with dynamic ip clients

[Norman Maurer]

Hi all,

im using ipsec-tools + gif interfaces for connection some diffrent
offices via ipsec. This works perfectly!
Now I want to setup some config which allow some people to connection
via ipsec client to this ipsec router. They have a dynamic ip so I think
a certificate is the way to go. But im not sure how i need to setup the
gif interface because the ip address will change probally.

So any idea ? I couldn't find any docu :-/

bye
Norman