From: "Nicolás Brailovsky" <nicolasbrailo@...>
Date: 2009-10-02T00:00:45+09:00
Subject: Re: Problems with SNMP

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2009/10/1 Rocir Santiago <rocirleite@gmail.com>

> Hi, Nicol=E1s.
>
> Thanks for the reply. My switch works fine with SNMP. It's 3com Baseline
> Switch 2226 Plus.


Problem is though it may support SNMP protocol it sure won't support all th=
e
options (OIDs) the RFC defines. Some switches do support listing known
devices, some don't.


> My doubt it's about the ruby code to find the MAC
> address of each computer "pluged" in my switch. I can figure out some
> examples at the doc page of this lib. But when I just try to get the
> ifPhysAddress, the application raises an error and I don't know why.
>

My experience with SNMP si mostly in C++, not Ruby, but it may be helpful t=
o
know which exception is your application raising. It may be because the OID
is not supported (no such instance exception) or because it's not defined i=
n
your code. To assert if the switch does support this OID try using snmpget
from console, not from within a program.

BTW, if I remember correctly ifPhysAddress will give you the iface's mac
internal to the switch, not the mac of the device in that port (there may b=
e
many known macs per port too).

Regards,
--=20
Nicol=E1s Brailovsky - http://nicolasb.com.ar/




>
> Here is the code:
>
> _________
> require 'snmp'
>
>  ifTable_columns =3D ["ifIndex", "ifDescr", "ifInOctets", "ifOutOctets",
> "ifPhysAddress"]
>  SNMP::Manager.open(:Host =3D> 'xxx.xxx.xxx.xxx') do |manager|
>      manager.walk(ifTable_columns) do |row|
>          row.each { |vb| print "\t#{vb.value}" }
>          puts
>      end
>  end
> _________
>
> I just added the ifPhysAddress to the example in the site. If I just
> remove the ifPhysAddress, it works fine.
>
>
> Nicol=E1s Brailovsky wrote:
> > Rocir, you should first check if your switch supports this
> > functionality. If
> > it does I'd try to do an snmpwalk through the complete table to find an
> > OID
> > providing a list of known mac addresses, which will most likely be
> > grouped
> > by interface (port).
> >
> > This link may come in handy: http://www.oid-info.com/index.htm
> >
> > Regards
> >
> > --
> > Nicol=E1s Brailovsky
> >  - http://nicolasb.com.ar/
> >  - http://monosinfinitos.com.ar/
> >
> > 2009/10/1 Rocir Santiago <rocirleite@gmail.com>
>
> --
> Posted via http://www.ruby-forum.com/.
>
>

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