Net::SNMP not retreiving Hex-STRING correctly

serge123 has asked for the wisdom of the Perl Monks concerning the following question:

Hello,

I'm having an issue with Net:SNMP and retreiving values listed as Hex-STRING. Here's a unix snmpwalk which looks OK:

snmpwalk -v 2c -c COMM 10.1.1.1 1.3.6.1.4.1.9.9.273.1.2.1.1.16
SNMPv2-SMI::enterprises.9.9.273.1.2.1.1.16.1.11.97.108.105.97.110.116.95.119.105.102.105.0.19.206.233.215.61 = Hex-STRING: 0A 40 12 81
SNMPv2-SMI::enterprises.9.9.273.1.2.1.1.16.1.11.97.108.105.97.110.116.95.119.105.102.105.0.144.75.10.176.166 = Hex-STRING: 0A 40 12 45
SNMPv2-SMI::enterprises.9.9.273.1.2.1.1.16.1.11.97.108.105.97.110.116.95.119.105.102.105.0.144.150.180.214.183 = Hex-STRING: 0A 40 12 96
SNMPv2-SMI::enterprises.9.9.273.1.2.1.1.16.1.11.97.108.105.97.110.116.95.119.105.102.105.0.144.150.182.172.193 = Hex-STRING: 0A 40 12 87

Here's the same walk with perl:

perl walktest.pl (walking 1.3.6.1.4.1.9.9.273.1.2.1.1.16)
Trying 'snmpwalk' on 10.1.1.1
1.11.97.108.105.97.110.116.95.119.105.102.105.0.19.206.233.215.61:
@
1.11.97.108.105.97.110.116.95.119.105.102.105.0.144.75.10.176.166:
@E
1.11.97.108.105.97.110.116.95.119.105.102.105.0.144.150.180.214.183:
@
1.11.97.108.105.97.110.116.95.119.105.102.105.0.144.150.182.172.193:
@

I get similar weird results if I do an snmpget with perl on 1 OID:

perl test.pl
1.3.6.1.4.1.9.9.273.1.2.1.1.2.1.11.97.108.105.97.110.116.95.119.105.102.105.0.19.206.233.215.61 = bÚZ`

Either way, the “Hex-STRING” data is never returned correctly. This happens with any OID holding a “Hex-STRING”. I don't have a problem with other OID types. At first I thought it was just a formatting issue so I played with printing the output using “hex” but it didn’t help. There also aren't enough chars sent back to be a formatting issue. I wonder if Net::SNMP can’t handle an OID value with a space in it?

The perl code I'm using looks like this:

use strict;
use Net::SNMP;
use BER;
use SNMP_Session;
use SNMP_util;
#variable declaration and assigment omitted...
print "Trying 'snmpwalk' on $host\n";
  @ret = &snmpwalk("$community\@$host\:\:\:\:\:$version", $oid );
foreach (@ret) {
 print "$_\n";
 }
[download]

As you can see I've been trying various SNMP modules. I've always get the same problem regardless of which way I query to OID.

Any help you can provide would be appreciated.

Thanks,
Serge

Comment on Net::SNMP not retreiving Hex-STRING correctly Download Code

Replies are listed 'Best First'.
Re: Net::SNMP not retreiving Hex-STRING correctly by Argel (Prior) on Mar 09, 2006 at 23:38 UTC
Instead of doing an snmpwalk have you tried a get_request? `$response_href = $session->get_request( $sysContact, $sysDescr, $sysLo +cation, $sysObjectID, $localDomain, $localHostname );` [download] You might also want to use Data::Dumper to output the results: `use Data::Dumper; print Data::Dumper->Dump([$response_href],['response hash']);` [download]	[reply] [d/l] [select]
Re: Net::SNMP not retreiving Hex-STRING correctly by atcroft (Abbot) on Mar 09, 2006 at 23:58 UTC
There was a bug report for Net::SNMP that seems to describe your issue. A former coworker of mine was referred to it when he experienced a similar issue a year or two ago. Hope that helps.	[reply]
Re: Net::SNMP not retreiving Hex-STRING correctly by serge123 (Initiate) on Mar 10, 2006 at 17:30 UTC
Hello, Thanks for the info. This following walk did the trick: `use strict; use Net::SNMP; use Data::Dumper; #Variable declaration & assigment ommited ($session, $error) = Net::SNMP->session( -hostname => $host, -version => $version, -community => $community, ); # do the SNMP walk, returns a hash ($bindings) = $session->get_table ($oid); # close the SNMP Session $session->close(); # print "Errors: $error\n"; print Data::Dumper->Dump([$bindings],['response hash']);` [download] The output looks as follows: $response hash = { '1.3.6.1.4.1.9.9.273.1.2.1.1.16.1.11.97.108.105.97.110.116.95.119.105.102.105.0.18.121.63.143.69' => '0x0a4012bb', '1.3.6.1.4.1.9.9.273.1.2.1.1.16.1.11.97.108.105.97.110.116.95.119.105.102.105.0.9.45.133.249.209' => '0x0a4012cc' }; The OIDs shown above actually have 3 values as indexes. It's easier to walk to base OID than gather the 3 index values and use a get. That's why I'm not using snmpget ;) Thank you very much! Serge	[reply] [d/l]
Re: Net::SNMP not retreiving Hex-STRING correctly by ikegami (Patriarch) on Jun 29, 2007 at 15:10 UTC
`@` is ASCII char `0x40`. `E` is ASCII char `0x45`. Your data is simply "packed". `unpack('H*', $_)` will convert the gobbledygook to "0A401281".	[reply] [d/l] [select]