[mrtg] Re: Duplicate IP?

Jeff Liebermann jeffl at comix.santa-cruz.ca.us
Tue Aug 10 18:19:25 MEST 1999

> I don't know if this is off topic, but is there a utility that will
> send an alarm when there is a duplicate IP on the network/subnet?

Linux has arpwatch.
SCO Unix OSR5 will complain to syslog and the console.
I believe that Netmon (not sure), a crippled version
that comes with NT4, will also detect dupes.  For the
full version, you'll have to extract the version of Netmon
that comes with MS SMS server.

All the other system can show that the results of:
	arp -a
will change when run repeatedly.  Arp -a will belch a table
of MAC addresses and IP addresses.  If there are two machines
on the lan, with different MAC addresses, but duplicate IP
addresses, it will show up as a constantly changing entry.
> Due to the nature of the systems I"m monitoring, it happens that once
> in a while a duplicate IP is setup on 2 devices.  I would like to be
> able to detect this and be informed (email/alpha pager) of this.

Disclosure of the operating system that you're running
is often helpful in getting a decent answer.

# Jeff Liebermann  Liebermann Design  150 Felker St #D  Santa Cruz  CA  95060
# 831.336.2558 voice  wb6ssy at ki6eh.#cca.ca.usa.noam  wb6ssy.ampr.org
# 831.421.6491 digital_pager    73557,2074  cis [don't]
# jeffl at comix.santa-cruz.ca.us  http://www.cruzio.com/~jeffl

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