found Bug in older Net-SNMP (or SNMP.pm.)

Hello there,

I got a terrible headache collecting some instance specific data from an Cisco Router using SNMPv2c, GET, NET-SNMP (Perl SNMP.pm) V.5.1.4 on an AIX 5.3.

Some time it works fine, but then there are errors. Perl canŽt find the responsed data. 

I traced the last 5 Days while looking for bugs in my code and found a strange behavior thanks to iptrace, wireshark and $SNMP::debugging =3.

It looks like if Net-SNMP v.5.1.4 sends a get request (say with request-id 10) waiting for a receive and "somehow" sees an earlier responsed packet (say with request-id 8).
Instead of comparing the request-id, the varbinds item name or atlast the timestamp, this response is taken.

The error appears randomly (using get/Bulkwalk/getbulk) too. 

If my community wasnŽt spoiled all over the dump, I would hand it to you. It put a tiny&dirty skript together which will replicate the error.

Thanks,

Bastian

 

 

 

###################################################use warnings; use SNMP;
use SNMP::Multi; my @data = <DATA>;
my @routers = qw (); #place routers
my @mib = qw ( ); #place mibs see list after __DATA__ my $nonrep = 0;
my $rep = 0;
my @nonrep = ();
my @rep = (); 
foreach my $ids ( @mib ) {
 foreach my $dainline ( @data ) {
 $da =~ s/\s+//;
 print "$da\n";
 if ($ids =~ /$dainline\.\d/) {
 push (@nonrep,$ids);
 print "found a nonrep\n";
 $nonrep++;
 
 } elsif ($m =~ /$dainline\b/) {
 push (@rep,$ids);
 print "found a rep\n";
 $rep++;
 } 
 } 
} my $methode = undef; if ($nonrep){
 @mib = ();
 push (@mib,@nonrep);
 $methode = 'get';
 &frag;
 $nonrep=0;
} if ($rep) {
 @mib = ();
 push (@mib,@rep);
 $methode = 'bulkwalk';
 &frag; 
} 
$nonrep = @nonrep;
print "Found $rep Reps and $nonrep Nonreps.\nUsing Methode: $methode!\n";
@mib=();
@nonrep=();
@rep=(); sub frag() {
 my $mib = undef;
 my $lastdefhe = 0;
 my $oid = 1;
 
 my $requested = SNMP::Multi::VarReq->new (
 nonrepeaters => $nonrep,
 hosts => [ @routers ],
 vars => [ $mib[0] ],
 ); 
 while (defined ($mib[$oid])) {
 print "ask for $mib[$oid]\n";
 $requested->add( vars => [ $mib[$oid] ] );
 $oid++;
 $lastdefhe++;
 }
 
 #print "Vars to request $lastdefhe\n";
 
my $session = SNMP::Multi->new (
 Method => "$methode",
 MaxSessions => 100,
 PduPacking => 32,
 Community => "xxx",
 Version => '2c',
 Timeout => 5,
 Retries => 3,
) or warn "$SNMP::Multi::error \n";
 
 $session->request ($requested) or print $session->error;
 
 my $resp = $session->execute(15) or print "Execute: $SNMP::Multi::error\n"; 
 
 undef %reprouters;
 
 if (defined $resp) {
 print "got response\n";
 for my $host2 ($resp->hosts()) {
 print "host $host2\n";
 $reprouters{$host2} = $host2;
 }
 }
 
 # *** Feststellen ob welche fehlen ***
 for $host3 (@routers) {
 if (!$reprouters{$host3}) {
 $tomdatum = localtime($now);
 print LOG "$now: $tomdatum $host3 hat nicht geantwortet\n";
 print "$now: $tomdatum $host3 hat nicht geantwortet.\n";
 }
 }
 
 if (defined $resp) {
 for my $host ($resp->hosts()) {
 print "looking host $host resultes\n";
 # *** Ist dieser host im Ergebnis vorhanden ***
 for my $result ($host->results()) {
 print "$result host resultes\n";
 if (defined $result) {
 if ($result && $result->error()) {
 print "got errors\n";
 # *** no value received for this*** 
 next; 
 } else {
 print "no errors\n";
 for my $varlist ($result->varlists()) {
 print "Varlist:\n", map {"\t" . $_->fmt() . "\n" } @$varlist;
 print "working $varlist list requestet with $methode\n";
 foreach (@{$varlist}) { foreach (@$_) {print "$_ \n";};};
 }
 }
 }
 }
 }
 } 
 }
} #sysObjectID 1.3.6.1.2.1.1.2 .0
#sysUpTime 1.3.6.1.2.1.1.3 .0
#tcpCurrEstab 1.3.6.1.2.1.6.9 .0
#ipMRouteHCOctets 1.3.6.1.2.1.83.1.1.2.1.16
#ipMRouteUpTime 1.3.6.1.2.1.83.1.1.2.1.6 
#ifLastChange 1.3.6.1.2.1.2.2.1.9 
#ifHCInOctets 1.3.6.1.2.1.31.1.1.1.6
#ifHCInUcastPkts 1.3.6.1.2.1.31.1.1.1.7
#ifHCInMulticastPkts 1.3.6.1.2.1.31.1.1.1.8
#ifHCInBroadcastPkts 1.3.6.1.2.1.31.1.1.1.9
#ifHCOutOctets 1.3.6.1.2.1.31.1.1.1.10
#ifHCOutUcastPkts 1.3.6.1.2.1.31.1.1.1.11
#ifHCOutMulticastPkts 1.3.6.1.2.1.31.1.1.1.12
#ifHCOutBroadcastPkts 1.3.6.1.2.1.31.1.1.1.13
#ifHighSpeed 1.3.6.1.2.1.31.1.1.1.15
#ipMRouteInterfaceHCInMcastOctets 1.3.6.1.2.1.83.1.1.4.1.7
#ipMRouteInterfaceHCOutMcastOctets 1.3.6.1.2.1.83.1.1.4.1.8
#casAuthenResponseTime 1.3.6.1.4.1.9.10.56.1.2.1.1.6
#casAcctResponseTime 1.3.6.1.4.1.9.10.56.1.2.1.1.22
__DATA__
1.3.6.1.2.1.1.2
1.3.6.1.2.1.1.3
1.3.6.1.2.1.6.9
1.3.6.1.2.1.83.1.1.4.1.7
1.3.6.1.2.1.2.2.1.9
1.3.6.1.2.1.31.1.1.1.6
1.3.6.1.2.1.31.1.1.1.7
1.3.6.1.2.1.31.1.1.1.8
1.3.6.1.2.1.31.1.1.1.9
1.3.6.1.2.1.31.1.1.1.10
1.3.6.1.2.1.31.1.1.1.11
1.3.6.1.2.1.31.1.1.1.12
1.3.6.1.2.1.31.1.1.1.13
1.3.6.1.2.1.31.1.1.1.15
1.3.6.1.2.1.83.1.1.4.1.7
1.3.6.1.2.1.83.1.1.4.1.8
1.3.6.1.2.1.83.1.1.2.1.6
1.3.6.1.4.1.9.10.56.1.2.1.1.6
1.3.6.1.4.1.9.10.56.1.2.1.1.22#########################################################

 


	
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