[logs] RE: Logging in the DMZ

From: Michael Batchelder (piranhabros@private)
Date: Mon Feb 09 2004 - 22:31:13 PST

  • Next message: Kohlenberg, Toby: "RE: [logs] Logging in the DMZ (fwd)"

    In regards to the stealth log server setup...  While I haven't
    ever done this (the thought of spewing log packets out lots of
    ports makes me nervous), just reading the descriptions people
    have posted or linked to, I think I'll throw in this tidbit.  It
    might a no-brainer for folks, but in any case...
    
    So let's say you are using a bogus IP address in syslog.conf +
    hard-coding a MAC address-to-IP address mappings in the hosts
    generating the logs to get the packets onto the wire.   Remember
    that if said wire is connected into a switch, which is often the
    case, then the configuration of the switch can play a role.  (I
    see the LinuxJournal article did not address this, and assumed
    layer 2 connectivity was provided by a *hub*, which simplifies
    things greatly.)
    
    With a switch, the needed behavior--broadcasting the log packets
    to ALL ports--is possible because a switch which has not learned
    which port to map a given MAC address will be in "learning" mode
    and may broadcast the packet to all ports, thus acting like a
    hub.  But that behavior is configuration-dependent, and the
    heavier the iron, the more ways things get switched.  So a Cisco
    29XX or 35XX is fairly straightforward, but if your DMZ segment
    is a VLAN off a 6509, you may be doing more funky things that
    could impact your ability to broadcast in the general direction
    of the syslog server...  And even 29XX's have modes for port
    security and such that may do stuff to unicast packets w/unknown
    MAC addresses.  Since you're hardcoding MAC addys in the hosts,
    might want to do it in the switch too.  Caveat administrator.
    
    Binky
    
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