DHCP over PPP - or how to use sockets instead of BPF?

[Sassy Natan]

 Hi All

 Can u please tell me how can I make my DHCP server bind to a ppp interface?
 I want to have a remote machines, connecting to a VPN server that is
 running a DHCP server, gets all the IP from the VPN Server.

 In other words: I have a machine call A connect to a VPN server over
 l2tp tunnel. This Machine A - has two network interface, eth0 which is
 connect to the Internet, eth1 which is the local network LAN
 (172.17.0.1).

 Machine A have a dial up to a the VPN server (Machine B) and get a IP
 address from the Radius Server (172.16.0.10). So  Machine A have:

 eth0 12.34.45.56 public IP address that my ISP provide me
 eth1 172.17.0.1 Local LAN
 ppp0 172.16.0.10 VPN connection

 Machine B, the VPN server has

 eth0 89.78.23.23 public ip address that my ISP provide me
 eth1 172.16.0.1 Local LAN
 ppp0 172.16.0.254 which is the VPN tunnel with 172.16.0.10

 On the VPN server I have configure the routing table so all network
 address to 172.17.0.0 go via  172.16.0.10

 Now, I configure some host in my network, behind the interface
 172.17.0.1, lets say 172.17.0.10 and I can get to all machine in
 172.16.0.0
 but what I want is to get the ip address for the network 172.17.0.0
 from the remote DHCP server which is install on the VPN server
 (172.16.0.1).

 I have configure a dhcp realy in network 172.17.0.0 which point to the
 dhcp server, but here is the problem:
 I can get the dhcp interface can't bind to the ppp0 interface.

 tcpdump on ppp0 do show that dhcp request are coming, but that never
 get into the dhcp service that is running.

 Binding it to the eth0 is not good enough :-(

 What Can I do to make this working? any idea?

 I know about this:
 https://lists.isc.org/pipermail/dhcp-users/2010-April/011197.html

 But I didn't manage to compile it, i get
 /home/Dev/dhcp4/dhcp-4.1.1/common/socket.c:279: undefined reference to
 `get_hw_addr'

 I'm using Ubuntu 9.10

 Can some one please help?
 I working all the day on this and still no good :-(


 Thanks
 Sassy