in reply to SNMP from script conflicts with snmpwalk

The simplest answer I can think of is the while loop..
    while (!$session->{ErrorStr} ) { 
        print( "q - $q, num jobs - $num_jobs, "
               . "comment - $share_comment, "
               . "tag - " . $$vars[0]->tag . "\n" );
------> ($q, $num_jobs) =  $session->getnext($vars);
    }

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..why isn't the marked line assigning $share_comment? Also, because of the while loop, it appears that you're attempting to read in a table (or a series of columnar objects), in which case you don't want to start with object .0 (although there's no harm in doing this because the SNMP RFCs state that columnar objects must never commence with a .0 suffix - unfortunately Nortel struggles to comply with this in their SNMP agents).

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Re^2: SNMP from script conflicts with snmpwalk
by bowei_99 (Friar) on Nov 15, 2005 at 00:12 UTC 
    ------> ($q, $num_jobs) =  $session->getnext($vars);

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    Duh, I knew it was something trivial. Yeah, I updated the line with 

    ($q, $num_jobs, $share_comment) =  $session->getnext($vars);

    [download]

    and it works,i.e. it shows the values I expect. I think I had changed it earlier in the code, but forgot to change this line, too.

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[select]
      If your IP addresses are getting jumbled up you now have to ask yourself: "are all my values that are returned on the same row?"

      If it is at all possible that particular rows have a field missing then your individual column getnexts are going to get out of sync.. you may be retrieving share name for row 12 while retrieving comment for row 15.

      To guard against this you are going to have to harvest the last integer from the OID of each column and ensure they are all the same. (The last OID of each column is the row number, or more accurately, the index of the row.. actually the index might be an IP address and consist of many integers.. The only right way to obtain the row number is to strip off the leading digits that match the OID of the variable you are getting - confused yet?).

      Read more... (3 kB)

      Whilst SNMP is a simple protocol to implement, it's not so simple to use.. you have my empathy.

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        I see. So, even though the output from snmpwalk turns out OK, I still get erroneous results when autointerpreting MIB values. So for that reason, it would be safe to use OIDs instead names? If so, it seems odd that snmpwalk returns what I expect, but perl returns another.

        For example, when I run the script, I get: 

        q - "A6_1640_cn", comment -
q - "D1_319_CN3", comment - ""
q - "130_1016_4+", comment - "61.134"
q - "130_1035_4+", comment - "61.116"

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        So, it seems that the script is seeing blank values for the first two queues, and is getting messed up. However, when I check those values using snmpwalk, things are what I expect:

        [burvil@localhost printer-list]$ foreach p ( A6_1640_cn D1_319_CN3 )
foreach? snmpwalk server-ip-address public .1.3.6.1.4.1.77.1.2.27.1.1 
+| egrep $p
foreach? end
enterprises.77.1.2.27.1.1.10.65.54.95.49.54.52.48.95.99.110 = "A6_1640
+_cn"
enterprises.77.1.2.27.1.1.10.68.49.95.51.49.57.95.67.78.51 = "D1_319_C
+N3"


[burvil@localhost printer-list]$ foreach p ( 10.65.54.95.49.54.52.48.9
+5.99.110 10.68.49.95.51.49.57.95.67.78.51)
foreach? snmpwalk server-ip-address public .1.3.6.1.4.1.77.1.2.27.1.3 
+| egrep $p
foreach? end
enterprises.77.1.2.27.1.3.10.65.54.95.49.54.52.48.95.99.110 = "57.13"
enterprises.77.1.2.27.1.3.10.68.49.95.51.49.57.95.67.78.51 = "61.88"
[burvil@localhost printer-list]$

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        Somewhat annoying, since one of the main reasons I chose SNMP over Net::SNMP or SNMP_Session was because it could parse MIBs, allowing me to write (in theory at least) more maintainable code.
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      Actually, the comments show up as IP addresses expected, but they are jumbled up, i.e. different values from what I see in Windows.... Hmm... the values from snmpwalk match with what's seen through the Windows share - perhaps something with this module?

      This is what the code looks like now. Only made a couple changes - since I only need the queue name and comments, I only collect that ... 

      sub QuerySNMP {
        use SNMP;
        #$SNMP::debugging = 2;
        $ENV{'MIBFILES'} = "LanMgr-Mib-II-MIB.my";
        my ($hostname) = shift @_;
        my ($session) = new SNMP::Session(
                DestHost => $hostname,
                Community => "public",
                UseSprintValue => 1,
        );

        if (!(defined($session))) {
                die "Session creation error:  $SNMP::Session::ErrorStr
+  - $!\n" ;
        }

        my ($vars) = new SNMP::VarList(['svPrintQName'],
                                                                   ['s
+vShareComment
'],
                                                                );
        my ($q, $num_jobs, $share_comment) =  $session->getnext($vars)
+;

        if ($session->{ErrorStr}) {;
                die "Getnext failed - error: " . $session->{ErrorStr} 
+. " - $!\n"
        }
        while (!$session->{ErrorStr} ) {
                print "q - $q, comment - $share_comment\n";
                my ($q, $share_comment) =  $session->getnext($vars);
        }

}

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[reply]
[d/l]

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