Written by James McDonald

October 24, 2008

Suppose you have the following configuration

Priv Network A---Windows XP Clients
Linux gateway (iptables NAT etc)
Linux gateway (iptables GRE and PPTP port 1723 NAT'd and forwarded to internal PPTP server)
Priv Network B---<linux PPTP Server>

Both gateways have ip_conntrack_pptp and ip_nat_pptp modules running and currentish kernels.

In my testing I wanted to find out if the PPTP server on Network B would support multiple connections from Network A. So on a single Windows XP workstation I brought up 2 connections. Everytime I brought the second PPTP connection up on the Windows XP client It would kill the current connection and display a 619 error. In the /var/log/messages log of each linux gateway would be a “kernel: ip_conntrack_pptp: error during exp_gre” error.

However multiple PPTP connections from separate Windows XP hosts on the same “Network A” worked fine.

Testing sometimes brings up unexpected behaviour.


Submit a Comment

Your email address will not be published. Required fields are marked *

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

The reCAPTCHA verification period has expired. Please reload the page.

You May Also Like…