Routing table drops packets via ppp0

From: Mark Devin (mdevin_at_ozemail.com.au)
Date: 10/21/03

  • Next message: Paul Mackinney: "Re: Thanks Pigeon for Your mailfilterrc" 
    Date: Tue, 21 Oct 2003 17:39:11 +1000
To: Debian User <debian-user@lists.debian.org>

    I am having some trouble getting routing to work properly on a box with
    three network connections. One, eth0, is connected to a router and is
    the default gateway. Another, ppp0 (eth1 - ADSL) is connected to a
    private network on the 192.168.17.0/24 address range. The third is a
    standard LAN (eth2) on 192.168.2.0/24.

     From the debian box, I can ping other machines connected via the ADSL
    modem via ppp0. I can also ping machines on the internet via eth0 from
    this box. In addition, any machine on the Office LAN can connect to
    machines on the internet.

    However, if a machine on the office LAN tries to connect to a machine on
    the 192.168.17.0/24 network, the packets disappear somewhere in the
    debian box. I can see the packets coming in with tcpdump but then they
    disappear. The debian box does not try to route them at all.

    Note that I have switched off all firewalling and switched ip_forwarding
    on in the kernel.

    The problem is related to the ADSL - ppp0 interface. The routing rules
    look OK. I can ping from the debian box via ppp0 to hosts on the
    connected network. However, if I ping from the office LAN, the packets
    do get to the debian box OK, but it doesn't route them out ppp0. It
    just seems to drop them. There is nothing in the logs to indicate any
    errors. The packets just disappear.

    The setup looks like this:

       Internet
           |
         x.x.47.224/27 Router x.x.47.225
           |
       eth0| x.x.47.226
           |
    #------------# (eth1 -ppp0 ADSL)
    # Debian Box #--192.168.17.2-->x.x.16.78-->192.168.17.0/24
    #------------#
           |
       eth2| 192.168.2.1
           |
           |
        Office LAN (192.168.2.0/24)

    The routing table looks like:
    # route -n
    Destination Gateway Genmask Flag Met Ref Use Iface
    x.x.16.78 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0
    x.x.243.224 0.0.0.0 255.255.255.224 U 0 0 0 eth0
    192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth2
    192.168.17.0 x.x.16.78 255.255.255.0 UG 0 0 0 ppp0
    0.0.0.0 x.x.243.225 0.0.0.0 UG 0 0 0 eth0

    Any ideas?

    Regards.
    Mark. 

    -- 
To UNSUBSCRIBE, email to debian-user-request@lists.debian.org 
with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
  • Next message: Paul Mackinney: "Re: Thanks Pigeon for Your mailfilterrc"

    Relevant Pages

    • DHCP Not working properly
      ... Desktop Workstations running Windows XP SP2 (wired network connections) ... These two machines will not pick up a DHCP address from the server. ...
      (microsoft.public.windows.server.sbs)
    • Re: Routing table drops packets via ppp0
      ... > three network connections. ... > private network on the 192.168.17.0/24 address range. ... > From the debian box, I can ping other machines connected via the ADSL ... > The routing table looks like: ...
      (Debian-User)
    • Re: network "stalls" ?
      ... Start, settings, control panel, network connections... ... > 30 seconds later I may or may not see all the machines on my network. ...
      (microsoft.public.win2000.networking)
    • Re: Calling for help
      ... this location and we had 20,000 connections showing on the PIX. ... After monitoring the connections we found a few machines that were infected ... The problem seems to occur when everyone is on the network around the middle ... >>to be able to browse the internet do any kind of external nslookup or ping ...
      (microsoft.public.windowsxp.network_web)
    • XP Home Workgroup - Access Denied on One PC...
      ... However, although I can see all 4 machines on the network, I ... I have checked the Windows firewall is not blocking connections on the first ... The network is connected by a wireless router on which the first pc is the ...
      (microsoft.public.windowsxp.general)