pgwiz1 has asked for the wisdom of the Perl Monks concerning the following question:

My Environment:
I downloaded and installed net-snmp5.4.2.1-1.win32.exe from sourceforge (needed a binary for windows that would work on Perl v5.8.9). I followed the README instruction to install the Perl modules:
ppm remove NETSNMP
cd (install folder)\Perl
ppm install NetSNMP.ppd
Test the install:
net-snmp-perl-test.pl
Result:
Testing translateObj
********************
Test passed. Result: .1.3.6.1.2.1.1.1
I test that my perl module is installed correctly:
perl -MSNMP -e 1

Issue:
Right now I am just writing some basic code to get the number of interfaces, and then print that number. I am getting nothing returned when I call $session->get. Here is my code. I am passing in the ip and the community string.

     use SNMP;
     $ENV{'MIBS'} = 'ALL';
     &SNMP::initMib();

     $session = new SNMP::Session(DestHost => $ARGV[0], Community =>$A
+RGV[1]);
     $numInts = $session->get('1.3.6.1.2.1.2.1.0');
     print "Number of Interfaces: $numInts\n";

[download]
When I run my code, I get:
Number of Interfaces:

I have tried a bunch of other things, but can't get it to return any values. If I just go to my commandline and type:
snmpget -v1 -c <community string> <ip> 1.3.6.1.2.1.2.1.0
I get results back as expected.....

Replies are listed 'Best First'.
Re: SNMP Perl Module methods not returning any values...
by Khen1950fx (Canon) on Sep 02, 2010 at 01:39 UTC
    To debug your script, you can start by adding verbose and debugging: 
    #!/usr/bin/perl

use strict;
use warnings;
use Devel::SimpleTrace;
use SNMP;

$SNMP::verbose   = 1;
$SNMP::debugging = 1;

$ENV{'MIBS'} = 'ALL';
&SNMP::initMib();

my $session = new SNMP::Session(DestHost => $ARGV[0], Community =>$ARG
+V[1]);
my $numInts = $session->get('1.3.6.1.2.1.2.1.0');
print "Number of Interfaces: $numInts\n";

    [download]
    That'll tell you why you're not getting back any values.

    Here's a different script with errors: 

    #!/usr/bin/perl

use strict;
use warnings;
use SNMP;

my $hostname  = 'localhost';
my $port      = 161,
my $community = 'public';

$SNMP::verbose     = 1;
$SNMP::debugging   = 1;
$SNMP::dump_packet = 1;

my $session = new SNMP::Session(
              'DestHost'     => $hostname, 
              'Community'    => $community,
              'RemotePort'   => $port,
              'UseSprintValue' => 1 );    
die "session creation error: Can't fire-up!\n" 
unless (defined $session); 

my $vars = new SNMP::VarList(['ipNetToMediaNetAddress'], 
           ['ipNetToMediaPhysAddress']); 

my  ($ip,$mac) = $session->getnext($vars); 
die $session->{ErrorStr} if ($session->{ErrorStr}); 

while (!$session->{ErrorStr} and $$vars[0]->tag eq 
"ipNetToMediaNetAddress") { 
    print "$ip -> $mac\n"; 
};
($ip,$mac) = $session->getnext($vars);

    [download]
    SNMP is just one of those modules that have a steep learning curve. It's also extremely difficult to get it to work properly, at least for me.

    As for interfaces, I don't think that SNMP will get that for you. Instead, try SNMP::Info. Here's an example using SNMP::Info::Layer3::NetSNMP: 

    
#!/usr/bin/perl

use strict;
use warnings;
use SNMP::Info;

$SNMP::verbose   = 1;
$SNMP::debugging = 1;

my $netsnmp = new SNMP::Info(
              AutoSpecify => 1,
              Debug       => 1,
              DestHost    => 'myrouter',
              Community   => 'public',
              Version     => 3
              )
    or die "Can't connect to DestHost.\n";
    
my $class = $netsnmp->class();
print "SNMP::Info determined this device to fall
       under subclass: $class\n";

    [download]
[reply]
[d/l]
[select]
Re: SNMP Perl Module methods not returning any values...
by pgwiz1 (Initiate) on Sep 02, 2010 at 14:43 UTC
    I FINALLY figured out my issue...in my session creation, I had to specify Version => 1 for it to work. Wanted to post back here incase others had a similar issue!
[reply]

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