mrtg and snmp help needed

[Chavdar Videff <chavdar@mr-bricolage.bg>]

Hi, list.

I am planning to set up a statistics generator for a number of hosts. My idea 
was to try mrtg.
I read a few articles on the net and installed on my test machine the packets 
mrtg and snmpd.
The test machine is a knoopix 3.6 installed on the hard drive and upgraded to 
debian-sid.
The hosts I intend to monitor are debian-sid too.
I tried the following sample configuration of mrtg in order to test things on 
the localhost:

/etc/mrtg.conf is liek this:

######################################################################
# Multi Router Traffic Grapher -- Sample Configuration File
######################################################################
# This file is for use with mrtg-2.5.4c

# Global configuration
WorkDir: /var/www/mrtg
WriteExpires: Yes


Title[^]: Traffic Analysis for

# 128K leased line
# ----------------
Title[leased]: a 128K leased line
PageTop[leased]: <H1>Our 128K link to the outside world</H1>
Target[leased]: 1:public@10.50.0.17:161
MaxBytes[leased]: 16000

and the /etc/snmp/snmp.conf is this:

com2sec readonly 10.50.0.0/25 public

However nothing happeds.
I included in the mrtg.conf a script that checks the test machine cpu and 
memory and I am sure mrtg works properly, for I get graphs, etc for the 
second configuration.

I am sure snmpd listens on all interfaces, for netstat -a says so.

But when I fire up 
# mrtg
I get the output:

root@it2:/home/chavdar# mrtg
SNMP Error:
no response received
SNMPv1_Session (remote host: "10.50.0.17" [10.50.0.17].161)
                  community: "public"
                 request ID: 1061100499
                PDU bufsize: 8000 bytes
                    timeout: 2s
                    retries: 5
                    backoff: 1)
 at /usr/share/perl5/SNMP_util.pm line 490
SNMPGET Problem for ifInOctets.1 ifOutOctets.1 sysUptime sysName on 
public@10.50.0.17:161:::::v4only
 at /usr/bin/mrtg line 1854
WARNING: skipping because at least the query for ifInOctets.1 on  10.50.0.17 
did not succeed
WARNING: no data for ifInOctets&ifOutOctets:public@10.50.0.17. Skipping 
further queries for Host 10.50.0.17 in this round.
ERROR: Target[leased][_IN_] ' $target->[0]{$mode} ' did not eval into defined 
data
ERROR: Target[leased][_OUT_] ' $target->[0]{$mode} ' did not eval into defined 
data

And indeed when I tcpdump I don't see the response on the snmp requests:
root@it2:/home/chavdar# tcpdump -i lo
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 96 bytes
11:39:03.256499 IP 10.50.0.17.32819 > 10.50.0.17.snmp:  GetRequest(39)  
interfaces.ifTable.ifEntry.ifInOctets.2 [|snmp]
11:39:05.254971 IP 10.50.0.17.32819 > 10.50.0.17.snmp:  GetRequest(39)  
interfaces.ifTable.ifEntry.ifInOctets.2 [|snmp]
11:39:07.255045 IP 10.50.0.17.32819 > 10.50.0.17.snmp:  GetRequest(39)  
interfaces.ifTable.ifEntry.ifInOctets.2 [|snmp]
11:39:09.255103 IP 10.50.0.17.32819 > 10.50.0.17.snmp:  GetRequest(39)  
interfaces.ifTable.ifEntry.ifInOctets.2 [|snmp]

I have no clue here. Can someone give me a hint, because in the articles I 
read in the official sites of mrtg, snmpd and elsewhere it is implied that 
everything works but not wirh me.

Thanks for your help!

Regards

Chavdar Videff