Re: Getting specific /32 from cflowd

From: Marcus C. Gottwald (
Date: Fri May 18 2001 - 02:41:35 PDT

  • Next message: Kitti Kosavisutte: "Re: Getting specific /32 from cflowd"


    Devon wrote (Thu 2001-May-17 17:19:36 -0400):

    > When I run "artsnets <filename>", I get the SrcAdr as a /24 or smaller (e.g.
    > /23, /22, etc). Is there anyway to get specific hosts (i.e. /32)? If not,
    > anyone have any suggestions? We are trying to track down an IP address that
    > is sending a lot of traffic.

    Within the flow information sent out by a Cisco, netmasks are
    included. These netmasks match an entry in the current routing

    If you have a specific route in the table (be careful with route
    aggregation, e.g. eigrp auto-summary), the mask should never be
    shorter than the routing entry.

    I have seen Ciscos being more detailled than expected. We had a
    single host-route into a network for which we also had a route
    with a shorter mask. However, all flows coming from or destined
    to a host within this network were given 32bit masks.

    For you, Devon, it might be sufficient to include a host route
    into the network the traffic is coming from. In any case, you
    should be able to do a "binary search" by adding two routes
    which are each 1bit longer, then take the one with all the
    traffic, split that one, ...

    Cheers, Marcus

    Condat AG
    Alt-Moabit 91d | 10559 Berlin | Germany
    Tel: +49.30.39094-167 | Fax: +49.30.39094-555-167
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