Net::SNMP get_request problem

[chrism01]

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;

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

[pg]

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+)*/

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";
}

[chrism01]

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

[insaniac]

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

[spiritway]

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';

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?

[insaniac]

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";
}

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...