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I'm having some routing problems with a machine and can't figure out why. eth0 is in 172.17.192.0/20 network. I'm trying to connect from a different network - 172.17.16.* but with ...
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  1. #1
    Just Joined!
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    Sep 2008
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    [SOLVED] routing table issue


    I'm having some routing problems with a machine and can't figure out why.

    eth0 is in 172.17.192.0/20 network.

    I'm trying to connect from a different network - 172.17.16.* but with no avail.
    I suspect it won't use the gateway.
    Is this a metric problem?


    Code:
    Kernel IP routing table
    Destination Gateway Genamsk Flags Metric Ref Use Iface
    139.10.0.0 * 255.255.0.0 U 0 0 0 eth1
    172.17.0.0 * 255.255.0.0 U 0 0 0 eth0
    default 172.17.198.110 0.0.0.0 UG 0 0 0 eth0

    Thanks!

  2. #2
    Linux Guru
    Join Date
    Nov 2007
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    1,754
    You have your network sizes mixed up.

    eth0 is in 172.17.192.0/20 network
    This is a network that spans 172.17.192.0 => 172.17.207.255

    But, your eth0 NIC has a subnet mask configured of 255.255.0.0 *which is* 172.17.0.0/16

    When trying to send packets, the kernel thinks that eth0 is on the same network as the destination (172.17.16.X). It sends an arp, gets no response, and then says it can't reach destination host.

    You need to fix the subnet mask on eth0.

  3. #3
    Just Joined!
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    Sep 2008
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    Of course!



    Thanks a lot, I really appreciate

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