No UDP between VMware hosts

Discussion in 'Linux Networking' started by wg, May 8, 2014.

  1. wg

    wg Guest


    There are 2 machines running on a vmware machine with hostnames LinuxA
    and LinuxB.

    On LinuxA a UDP server is listening on port 5090 on all interfaces
    On LinuxB a UDP message is sent with netcat:
    echo XXX | netcat -uvv LinuxA 5090

    However, the message sent from LinuxB to LinuxA is not received.

    Using a diffeerent posrt, e.g. 32000 does not help.

    TCP traffic works between LinuxA and LinuxB.
    Running the command on LinuxA works as required.

    Running 'iptables -L' shows that there is no paket filter on either

    Any hints?

    Thanks for reading.
    wg, May 8, 2014
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  2. wg

    Tauno Voipio Guest

    Usually the first step is to catch the traffic on both
    hosts with Wireshark or tcpdump. The traffic caught
    with tcpdump can be stored on disk for later analysis
    using Wireshark:

    tcpdump -s 1500 -w grabfile

    You should see the traffic from A to B on both hosts.
    Also, the possible response by B should be visible.
    Tauno Voipio, May 8, 2014
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  3. wg

    Bob Hauck Guest

    I am not so familiar with VMware but on VirtualBox the default network
    setup (called "NAT") does not allow guests to talk to each other. If
    that is desired a different network option must be specified ("bridged"
    or "internal").

    It think VMWare has similar options. You might want to check how the
    VMWare networking is set up for these two hosts.
    Bob Hauck, May 10, 2014
  4. wg

    wg Guest

    Problem solved;

    with tcpdump I noticed that UDP packets with size < 4 are not arriving
    at the destination server.
    This is on a VMware 4.5 with SuSE SLES11/SP2.
    I changed the application and things are running ok.

    Thanks guys for your comments.
    wg, May 13, 2014
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