The asppp.cf configuration file for a remote host is the same as the one described in "Parts of Basic Configuration File", except for the addition of the parameter negotiate_address:
ifconfig ipdptp0 plumb dummy mojave up path interface ipdptp0 peer_system_name mojave-ppp connectivity_timeout 300 negotiate_address on |
The negotiate_address parameter indicates whether or not local IP address assignment is obtained through negotiation and assigned dynamically. If set to on, the IP address supplied by the server is used as the client's local address for the duration of the connection.