[pptp-server] Contacting a PPTP Server behind a Linux box w/o ip_masq_vpn ?

[Frederic SOULIER]

Hello there,

  I have to do a very common thing :
  Configure a Linux Box to allow access from an external PPTP client
(W98,WNT,W2K) to a internal (on the LAN) PPTP server (PoPToP, ...).

  My problem is that I have only a linux 2.2.13 kernel and cannot patch
it !
  
  I have portforwarding (TCP 1723) installed on the linux box. PPTP/CTRL
connection is ok. How can I handle GRE packets ? ipfwd works well from
the client to the server but since Linux masquerading (on my 2.2.13
kernel) doesn't handle the GRE protocol (47) no answer is given to the
client.

  So, I'm looking for an alternative to ipfwd (another application),
something like a PPTP/GRE proxy (maybe transparent proxying).

  Any idea ?

Frederic