OT: query routers tables

[Les Mikesell]

On Wed, 2007-01-03 at 15:47 +0100, Mogens Kjaer wrote:

> > This question is way off topic, sorry.  I have googled and googled and have
> > not come up with a answer to my question.
> > 
> > I want to query a switch (via SNMP I think) to get a list of systems
> > attached to it.  I am using Nagios and would like to determine 
> > switch/router
> > dependencies.  Trace route will not work because it will not show
> > routers/switches for systems on the same sub-net as the system doing the
> > trace route and I have seen where it does not return the network based
> > switch a system is attached to, just the router.  If I could get a list
> > systems attached to a router/switch (not a personnel switch, a managed
> > switch) I can correlate the information and build dependencies.  I have a
> > hand-held Fluke network tester than runs Linux that will do this for me 
> > when
> > I type in a hostname, I would rather do it programmaticly because I have
> > over 300 systems I need to do.  I am open to any method that works that I
> > can script so I don't have to do it every time a new system appears.  Just
> > in case it matters some systems are attached to a V-lan off a managed 
> > switch
> > and I do NOT have admin rights to the routers or switches.
> > 
> 
> I wrote a C program that uses SNMP for this.
> 
> It queries the switches and hubs for the MAC addresses
> seen at each port and the number of bytes in/out.
> 
> Some switches have a MAC to IP table, else I would
> ask the ARP table of the router for a table like this.

OpenNMS (http://www.opennms.org) does this if you enable
it.

> The program then prepares a nice top-10 on the
> intraweb showing which computers are generating
> most traffic, and another table with traffic
> at each switch/hub port.

Ntop (http://www.ntop.org) will do nice summaries of traffic
by hosts/ports/whatever for whatever systems are bridged
to the collecting port.

-- 
  Les Mikesell
   lesmikesell at gmail.com