PPTP passthrough problem

Discussion in 'Tomato Firmware' started by peterjohn, Aug 30, 2011.

  1. peterjohn

    peterjohn Networkin' Nut Member


    my Home-Network contains a Linksys WRT54GL router with the Tomato 1.28 firmware. Now i'm trying to connect a Synology NAS (with a PPTP VPN-Server on it) in this network, but from an external network. So i have tried the following router settings:

    [1] In Tomato webadmin i created a 'Port Forwarding' (Proto: tcp, Ext Ports: 1723, Int Address: ... the NAS/VPN-Server) and 'NAT Helpers > GRE/PPTP' was checked

    [2] Under 'Scripts > Firewall' i made those additional rules:

    iptables -t nat -I PREROUTING -p tcp --dport 1723 -j DNAT --to
    iptables -I FORWARD -p tcp -d --dport 1723 -j ACCEPT
    iptables -t nat -I PREROUTING -p 47 -j DNAT --to
    iptables -I FORWARD -p 47 -d -j ACCEPT

    At no time i was able to establish an VNP connection from external networks to my home-network VPN-Server. The VPN-Client log contains:

    I do not understand why IP GRE is not forwarded correctly. TCP Forwards (e.g. port 8080) are working perfect. Does anyone have any idea how I could solve this problem?

  2. Toxic

    Toxic Administrator Staff Member

    GRE is not a port that you can forward, its an IP protocol - not port 47

    try forwarding port 1723
  3. Toxic

    Toxic Administrator Staff Member

    also make sure PPTP Pass through is enabled.
  4. peterjohn

    peterjohn Networkin' Nut Member

    Thats true. So i had forwarded both, protocol 47 (i think that's GRE) and tcp-port 1723.

    Is there any other option than 'NAT Helpers > GRE/PPTP' in Tomato 1.28 web interface? I only checked this one.

    Telnet from external networks to the VPN-Server ('telnet ***.dyndns.org 1723') was successful, so i think there's a problem with GRE Forwarding.
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