Net::SNMP get_request problem

chrism01 has asked for the wisdom of the Perl Monks concerning the following question:

Monks
I'm trying to cvt a cmd line snmp call like this:

/usr/bin/snmpget -Oq 1.2.3.4 passwd interfaces.ifTable.ifEntry.ifOutOctets.6

to a Perl Net::SNMP cmd as part of a Perl script.
I tried the following, based on the example from the relevant CPAN module page:


#!/usr/bin/perl -w
use strict;
use Net::SNMP;

my ($session, $error) = Net::SNMP->session(
  -hostname  => shift || '1.2.3.4',
  -community => shift || 'passwd',
  -port      => shift || 6
);

if (!defined($session)) {
  printf("Session ERROR: %s.\n", $error);
  exit 1;
}

#my $octets_out = '1.3.6.1.2.1.1.3.0';
my $octets_out = 'interfaces.ifTable.ifEntry.ifOutOctets';

my $result = $session->get_request(
  -varbindlist => [$octets_out]
);

if (!defined($result)) {
  printf("get_req ERROR: %s.\n", $session->error);
  $session->close;
  exit 1;
}

printf("octets_out for host '%s' is %s\n",
  $session->hostname, $result->{$octets_out}
);

$session->close;
[download]

and got the following result:

get_req ERROR: Expected OBJECT IDENTIFIER in dotted notation.

Can anybody help me out, bearing in mind that I've never used SNMP before?
(In both examples I've obscured the ip address + communitystring)
Thx
Chris

Comment on Net::SNMP get_request problem Download Code

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Re: Net::SNMP get_request problem by pg (Canon) on Sep 29, 2005 at 02:43 UTC
If you open up the source code (the code is in Net::SNMP::PDU), you will see that the module is expecting the input to match `/^\.?\d+\.\d+(?:\.\d+)/` [download] And the format that you commented out was just fine. `use strict; my $a = '1.3.6.1.2.1.1.3.0'; if ($a =~ /^\.?\d+\.\d+(?:\.\d+)/) { print "match\n"; }` [download]	[reply] [d/l] [select]
Re: Net::SNMP get_request problem by spiritway (Vicar) on Sep 29, 2005 at 01:59 UTC
I've checked your code. It runs when I reverse your comments, as follows: `my $octets_out = '1.3.6.1.2.1.1.3.0'; #my $octets_out = 'interfaces.ifTable.ifEntry.ifOutOctets';` [download] Not surprisingly, I got a message telling me that host 1.2.3.4 wasn't responding, but it certainly is a hopeful indication that you're on the right track. Could it be that your code (as I changed it) was working, but you thought it was hanging because it was timing out?	[reply] [d/l]
Re: Net::SNMP get_request problem by chrism01 (Friar) on Sep 29, 2005 at 03:59 UTC
Actually, I should have pointed out that the line with the commented out IP address was from the CPAN example. (maybe I should have deleted it :) ) The cmd line code I inherited uses the names format instead, and I don't know what the numbers would be. Is there any way of continuing to use the names, as it's a darn sight more informative/maintainable? If not, how do I find out the numbers? Thx again Chris	[reply]
Re^2: Net::SNMP get_request problem by insaniac (Friar) on Sep 30, 2005 at 17:37 UTC
one quick way to find out the numbers (OIDs) of the names, is to use the `snmpwalk` or `snmpget` command with the option `-On`. example: `insaniac][musashi: ~ : snmpget -On -v1 -cpublic localhost interfaces.i +fTable.ifEntry.ifOutOctets.1 .1.3.6.1.2.1.2.2.1.16.1 = Counter32: 4093056087 insaniac][musashi: ~ : snmpget -v1 -cpublic localhost interfaces.ifTab +le.ifEntry.ifOutOctets.1 IF-MIB::ifOutOctets.1 = Counter32: 4093056087` [download] to ask a question is a moment of shame to remain ignorant is a lifelong shame	[reply] [d/l] [select]
Re: Net::SNMP get_request problem by insaniac (Friar) on Sep 30, 2005 at 08:57 UTC
From my days with playing with Net::SNMP, I remember that I liked the get_next_request more than get_request and all my OIDs start with a dot. Some working code (which i seem to copy paste a lot): my ($s,$e)=Net::SNMP->session(-hostname=> $ip, -community =>$community +); if (!defined($s)) { printf("error: %s.\n", $e); exit 1; } $oid = ".1.3.6.1.4.1.9.9.42.1.2.1.1.2"; my @args = ( -varbindlist => [$oid]); while ( defined $s->get_next_request(@args) ) { $_ = ( keys(%{ $s->var_bind_list }) )[0]; if (!oid_base_match($oid, $_)) { last; } printf("%s => %s", $_, $s->var_bind_list->{$_}); my @n = split /\./, $_; print " (index: ",$n[$#n],")\n"; @args = (-varbindlist => [$_]); } # Let the user know about any errors if ($s->error() ne '') { print $s->error(),"\n"; } [download] Try to see if you understand this small example (read: perldoc it);-) cheers PS: I think your problem is just that you have to start your OID with a DOT (like the error message says). Nothing more... to ask a question is a moment of shame to remain ignorant is a lifelong shame	[reply] [d/l]