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Strange Security Message

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ghilly63
ghilly63 Posts: 3
in Linux Security

My internal network runs with a 192.168.2.x class C address range but my router (It's also the DHCP server of course) keeps emailing me the following message:

2009-11-17 19:53:00 - UDP Flood - Source:192.168.1.3

,58393,LAN - Destination:194.168.4.100,53,WAN

How come the source is 192.168.1.3?

The Destination is my ISP DNS server I guess

I hope someone can explain whats going on,

Gordon

P.S. I don't run an internal DNS Server.

:blink:

Comments

  • mfillpot
    mfillpot Posts: 2,177
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    The issue I see is that the traffic is coming from a 192.168.1.X subnet and going to a 192.168.4.X subnet. That really doesn't make sense since you are running on a 192.168.2.X subnet.

    It sounds like it is receiveing misaddressed packets from the outside connection. Can you confirm the port(s) that have been receiving those packets, your outside connection IP address and the subnet group used on your outside connection to see if the addressing corresponds?
  • ghilly63
    ghilly63 Posts: 3
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    Hi, Thanks for your response, just a quick correction on your reply:

    2009-11-19 09:50:53 - UDP Flood - Source:192.168.1.3
    ,57285,LAN - Destination:194.168.4.100,53,WAN

    The destination is a 194 not a 192 subnet,

    My external IP currently is 77.101.212.219

    My Router primary DNS is 194.168.4.100 which matches the Destination address and its always port 53, which you would expect.

    The router internal address is 192.168.2.1

    DHCP is delivering an IP address range of 192.168.2.100 through 192.168.2.200

    So it makes no sense to me, Could my router be compromised somehow?

    Regards

    Gordon
  • mfillpot
    mfillpot Posts: 2,177
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    Good catch seeing my typo.

    I don't think that your router has been compromised, I would recommend trying to capture some of the questionable packets to analyze their structure to see if they all have the same contents or if the data changes. The UDP flood may be the result of an attempted denial of service attack or maybe even the result of an error on an outside connection, packet analysis can help you to identify the cause and potentially modify your firewall rules to discard those packets.
  • ghilly63
    ghilly63 Posts: 3
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    Thanks Karma I'll see what I can find out

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