Re: Router Discovery

[magnus () linuxtag org (Nils Magnus)]

Re,

On Wed, Dec 22, 2004 at 10:53:15AM +0530, Ankam, Pankaj wrote:

> Is there any way by which I can find all the routers on my network?
>
> Or
>
> Given a IP address, can I find out if that IP is a router or not?

This is a little bit OT in terms of nmap, however, here is the short
answer: nmap does quite a decent job with its -sV and -O scans and
prints its assumptions based on the operating system and the port
signature whether a system is a router or not.

You get much better results if you are directly connected (on link
layer) to a segment. Take a sniffer like tcpdump/ethereal and watch for
packets directed to one and the same MAC address but with different IP
addresses; this is the very nature of a router (or of some advanced
autofailover loadbalancing facilities, for that matter ...).

Regards,

Nils Magnus
Program-Chair LinuxTag 2004 Free Conference Program

LinuxTag 2004: Where .com meets .org - magnus () linuxtag org

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