DHCP Activity Logging

Discussion in 'Cisco' started by Fred Atkinson, Dec 10, 2005.

  1. Is there any way to make a Cisco 831 router log DHCP changes
    from the provider?

    I'm seeing some weird things. Sometimes, I discover I'm
    getting a 192.168.#.# address instead of a public IP address. I've
    discussed it with Mediacom, but they don't believe me. When I get a
    private IP address on the provider interface, I am unable to use the
    Internet for some strange reason. Since I have VOIP at home, that's a
    problem (no phone service when this happens).

    If I could dump DHCP activity to a file on my TFTP server, I
    could keep it and provide it to Mediacom so perhaps I could get them
    to fix this.


    Fred Atkinson, Dec 10, 2005
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  2. Hi Fred,

    What you could do - you can turn on the debug information for the DHCP
    client. It will log everything related to a DHCP activity. Here is a link to
    the Cisco.com website with some information:


    You may install the Syslog server on your PC (or any PC which is always on),
    and send all log activity to that PC. If you do not have your PC always on,
    you can log to internal router's buffer, and check it daily, if you have

    Good luck,

    CiscoHeadsetAdapter.com, Dec 10, 2005
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  3. Mike,

    Sounds like a plan. I've turned on the debug dhcp option. I'm
    searching for a free syslog server but so far have been unable to
    locate one.

    Any suggestions?

    Thanks very much, sir.

    Fred Atkinson, Dec 10, 2005
  4. Fred Atkinson

    DoubleD4 Guest

  5. Fred Atkinson

    Hansang Bae Guest

    3CDaemon from 3Com



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    Hansang Bae, Dec 10, 2005
  6. I've installed the KIWI syslog server. It doesn't seem to be
    receiving the DHCP activity. I used the 'release dhcp e1' and waited
    for the activity to finish. Then I used the 'renew dhcp e1' and
    waited again.

    No activity registered on the KIWI server.

    I'm suspecting that I need to enter a Cisco command into the
    831 to make it send to the KIWI server. Fortunately, my PC has a
    static IP address.


    Fred Atkinson, Dec 11, 2005
  7. Fred,

    Check you router configuration. You should have logging to the host

    logging host <PC IP Address>
    logging trap <logging desired level>

    You may change the "facility" for your messages, but it should work even
    without it.

    logging facility <facilily name>

    To check avalable options you can always enter "?" after the command.

    You can always check how and where you send your Syslog messages by typing
    the "show log" command - first section will show you logging status.

    Another thing - sometimes Kiwi Syslog just does not work. Try to stop/start
    it a couple times.

    Good luck,

    CiscoHeadsetAdapter.com, Dec 11, 2005
  8. That's pretty close to what I had in there already. I
    re-entered them, however. I'm getting the same results, no messages.
    Shouldn't it log when I release and renew the e1 interface? It


    Fred Atkinson, Dec 11, 2005
  9. Well,

    I've let the syslog server run for a few days. It has some
    error messages, but it doesn't show any DHCP activity from my router.
    Still confused.

    Fred Atkinson, Dec 14, 2005
  10. Fred Atkinson

    Merv Guest

    exactly what debug commands where entered ?

    I believe for the router as a DHCP client "debug dhcp detail" would be
    the one to use
    Merv, Dec 14, 2005
  11. I put yours in. Then I released and renewed the lease. The
    actions never logged on the syslog server, either.

    What I want to track is what the IP address changes are. I am
    getting some entries, but only that the interface is up or down. There
    is no reference to changes in the IP address.


    Fred Atkinson, Dec 15, 2005
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