Inet connectivity via L2TP connection

  • elijah_t

    elijah_t - 2005-12-24

    OK. WinXP Pro SP2.
    coLinux is 0.6.2 with Fedora Core 1 min image
    Network Layout:

    | PC |--network cable-> |Cable Modem| ---Coax.Cable-----> Infrastructre....

    Network Connections have:

    1. Local Area Connection

    On an Ethernet Adapter

    Dynamic IP, which it gets from the infrastructure provider (A Cable company)DHCP. It usualy starts with 172.23..... :(

    2. L2TP Connection

    To the ISP...

    Gets dynamic IP from the ISP.

    I can disconnect it, and the LAN (1.) connection will still be connected and having the same IP. No Inet connectivity though (duh...)

    3. coLinux TAP

    on A TAP installd by coLinux


    when coLinux is not running it says "Network Cable Unplugged", once the coLinux is up, it says connected.

    coLinux has lo and eth0 interfaces, eth0 is, gateway is, bla bla

    I can ping from coLinux
    I CAN'T ping (though Windows claims it to be online...) - it gives me "Host Unreachable)

    So, now what do I have to do to get Inet from coLinux?

    • elijah_t

      elijah_t - 2005-12-24

      Ok, played with it a bit...

      The LAN connection (part of the L2TP) has IP adress of aaa.bbb.95.227 so, I gave the coLinux TAP an IP of aaa.bbb.95.226 and to eth0 inside coLinux - aaa.bbb.95.222 (don't ask me why...), now...

      I still can't ping shit from inside coLinux, but I can ping aaa.bbb.95.222 (eth0 om coLinux)and aaa.bbb.95.226 (TAP) from windows prompt and I can ssh from Windows to coLinux.

      I wonder what that may mean.. :\

    • Danny Staple

      Danny Staple - 2005-12-26

      Have you bridged (under windows) the tap network and your ethernet (or other real network interface)?

      To do so - select icons for both networks, right click, and click bridge to bridge them. You should then be able to ping the gateway.

    • elijah_t

      elijah_t - 2005-12-26

      Nah... bridging is no good. If I bridge the TAP and the LAN connections I can't ping nothing and my Internet connection in Windows stops workin. BUT

      I restored it all back, e.g. :

      LAN has the whatever ip it needs to have (assined by  CSP)

      TAP has IP of
      L2TP connection is being shared (ICS) with TAP connection

      eth0 on coLinux has IP of

      NOW THE TRICK IS to allow in windows incoming ICMP. Now I can ping eth0 to TAP and back.

      And I have Inet in coLinux.

      Seems pretty easy. Dunno why it took me so long. Maybe it's better not to stay up untill 4AM ? : )


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