GS has asked for the wisdom of the Perl Monks concerning the following question:

Hello monks,
I am trying to do a snmpwalk for interface descriptions on a cisco device using SNMP module, it looks there is no walk procedure available, I am trying the following and it walks through the whole MIBs instead of the branch just for interfaces.
Below is the script:
appreciate help, thanks! 
 
use SNMP;
 
 $sess = new SNMP::Session(DestHost => cisco_router, Community => publ
+ic);
 $vb = new SNMP::Varbind([.1.3.6.1.2.1.2.2.1.2]);
 do {
    $val = $sess->getnext($vb);
    print "@{$vb}\n";
 } until ($sess->{ErrorNum});

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Replies are listed 'Best First'.
Re: snmpwalk problem
by davidrw (Prior) on Jun 20, 2005 at 01:36 UTC
    I can't comment directly about your code, but i see that SNMP::Info can provide "Interface Information" and that SNMP::Util actually has a walk() method for doing a snmpwalk ... are either of these better suited for your needs?
[reply]
[d/l]
      David, SNMP::Util requires ucd-snmp to be installed, and I am working in a production environment where as a user I am not able to install any packages at this point. regards.
[reply]
Re: snmpwalk problem
by monarch (Priest) on Jun 20, 2005 at 07:07 UTC
    I always test the returned varbind to ensure the OID hasn't incremented past the branch that I want. (getnext always gets the next OID regardless of what the initial OID was). (OID = object identifier, it's the .1.3.6.1... thing) 

      my $baseoid = ".1.3.6.1.2.1.2.2"; # ifTable
  my $thisoid = $baseoid;
  while ( 1 ) {
    $val = $sess->getnext($thisoid);
    last if ( $thisoid !~ m/^$baseoid\./ );
    last if ( $sess->{ErrorNum} );

    print( "@{$thisoid}\n" );
  }

    [download]

    Update: I always use Net::SNMP, too. Why? Because it's pure Perl, unlike SNMP which relies on the UCD tools. The latest Net::SNMP, however, does some tricky SNMPv3 stuff that requires a recent version of Perl, making it not that useful for running on old installations of 5.005.. in which case getting an older copy of Net::SNMP isn't a bad idea.

[reply]
[d/l]
[select]
      Monarch,
      Tried the following and it didn't like the OID, see the output below.
      rgds. 
      my $baseoid = ".1.3.6.1.2.1.2.2"; # ifTable
  my $thisoid = $baseoid;
  while ( 1 ) {
    $val = $sess->getnext($thisoid);
    print "$val \n";
    last if ( $thisoid !~ m/^$baseoid\./ );
    last if ( $sess->{ErrorNum} );
    print( "@{$thisoid}\n" );


Cisco Internetwork Operating System Software 
IOS (tm) 3600 Software (C3640-JS-M), Version 12.1(5)T8,  RELEASE SOFTW
+ARE (fc1)
TAC Support: http://www.cisco.com/cgi-bin/ibld/view.pl?i=support
Copyright (c) 1986-2001 by cisco Systems, Inc.
Compiled Tue

      [download]
[reply]
[d/l]
      A reply falls below the community's threshold of quality. You may see it by logging in.
Re: snmpwalk problem
by decnartne (Beadle) on Jun 21, 2005 at 14:52 UTC
    I use the following in a script I run to get a list of interfaces from Cisco... (perhaps the leading "." on your varbind is the culprit? - or not...) 
    ...

use strict;
use Net::SNMP;

...

sub get_if_ids
{
    my ( $hostname ) = @_;
    my %ifs;
    my $ifEntry = "1.3.6.1.2.1.2.2.1.2";

    my ( $session, $error ) = Net::SNMP->session(
        -hostname  => $hostname,
        -version   => 1,
        -community => "public" );

    if ( !defined( $session ) )
    {
        print "ERROR: SNMP - $error\n";
        return undef;
    }

    my $result = $session->get_next_request( -varbindlist => [$ifEntry
+] );

    while ( defined( $result ) )
    {
        foreach my $key ( keys %$result )
        {
            if (  $key !~ /^$ifEntry/ )
            {
                $result = undef;
                last;
            }

            #  process $result...
            #  Update:  $key is 1.3.6.1.2.1.2.2.1.2.n for the nth inte
+rface
            #           $result->{$key} is interface name

            $result = $session->get_next_request( -varbindlist => [$ke
+y] );
        }
    }

    $session->close();

    return \%ifs;
}

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    decnartne ~ entranced

[reply]
[d/l]
      Thanks.
[reply]

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