no SNMP remote communication

no SNMP remote communication

Post by Greg Le » Thu, 30 Dec 2004 06:37:14



I've just installed net-snmp, v 5.2, on two Linux systems,
and locally, each works, but they don't talk to each
other.  "snmpget ling sysUpTime.0" gives "snmpget: Timeout".

I started the snmpd daemon on both systems with "-d", and
when I watch /var/log/snmpd.log, I see no packets sent or
received on either system.  There's no firewall, so far as
I know.  On the sending system side, "netstat -u -s" gives
"258926 packets sent" before the "snmpget" and afterward,
gives "258932 packets sent", but on the receiving system,
the figure for packets received doesn't change.

Any ideas about what I'm doing wrong?

(Sending system has Linux 2.6.6, receiving system has Linux
2.6.9.)

--

 
 
 

no SNMP remote communication

Post by Allen McIntos » Thu, 30 Dec 2004 11:17:05



> I've just installed net-snmp, v 5.2, on two Linux systems,
> and locally, each works, but they don't talk to each
> other.
> ...
> Any ideas about what I'm doing wrong?

Things to try and things I've been bitten by:

- Do you need to force V2c?
- Do you need to edit the config file?
- Is firewalling turned off?
- Run ethereal at the far end.  Better yet, run ethereal at both ends.

 
 
 

no SNMP remote communication

Post by Greg Le » Fri, 31 Dec 2004 01:51:19




> > I've just installed net-snmp, v 5.2, on two Linux systems,
> > and locally, each works, but they don't talk to each
> > other.
> > ...
> > Any ideas about what I'm doing wrong?
> Things to try and things I've been bitten by:
> - Do you need to force V2c?

"-v1", "-v2c", "-v3" give the same result.

Quote:> - Do you need to edit the config file?

I don't understand the config options very well, but I have done
considerable fiddling with the config files.

Quote:> - Is firewalling turned off?

I think so.  I never set it up, there is no reference to "iptables"
in my init scripts, and "iptables -L" shows no entries.

Quote:> - Run ethereal at the far end.  Better yet, run ethereal at both ends.

I never heard of ethereal.  I'm in the process of installing it.

Thanks for the suggestions.
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no SNMP remote communication

Post by Allen McIntos » Fri, 31 Dec 2004 04:19:40


Quote:> I never heard of ethereal.  I'm in the process of installing it.

Think of it as tcpdump with lots more decodes and a GUI.
 
 
 

no SNMP remote communication

Post by Greg Le » Fri, 31 Dec 2004 05:55:03



> > I never heard of ethereal.  I'm in the process of installing it.
> Think of it as tcpdump with lots more decodes and a GUI.

I've installed it now on both the system I'm sending a snmp
request from and the system I'm sending it to.  I see the
snmp GET requests on the sending system.  I see lots of
snmp traffic looking from the receiving system, but nothing
coming from me.  It's fun, but so far it hasn't told me
anything I didn't know about my problem.
--

 
 
 

no SNMP remote communication

Post by Greg Le » Sat, 01 Jan 2005 00:58:04




> > > I never heard of ethereal.  I'm in the process of installing it.
> > Think of it as tcpdump with lots more decodes and a GUI.
> I've installed it now on both the system I'm sending a snmp
> request from and the system I'm sending it to.  I see the
> snmp GET requests on the sending system.  I see lots of
> snmp traffic looking from the receiving system, but nothing
> coming from me.  It's fun, but so far it hasn't told me
> anything I didn't know about my problem.

Ha.  Got it working by sending to and listening on a tcp port
instead of the default udp port 161.  I'm conjecturing that
my receiving system, on a different subnet, is behind some
filter.

--

 
 
 

no SNMP remote communication

Post by Allen McIntos » Sat, 01 Jan 2005 11:24:22


Quote:> I've installed [ethereal] now on both the system I'm sending a snmp
> request from and the system I'm sending it to.  I see the
> snmp GET requests on the sending system.  I see lots of
> snmp traffic looking from the receiving system, but nothing
> coming from me.  It's fun, but so far it hasn't told me
> anything I didn't know about my problem.

Ah, but it has.  Without a sniffer, you have no way of knowing if
packets are being sent and received.  With the sniffer, you now know
(almost) for certain that packets are leaving the sending system and
never arriving at the receiving system.  You know that the showstopper
is not a configuration problem, and that the traffic is not getting
through.  You confirmed this when you changed the port number and got
things working.
 
 
 

no SNMP remote communication

Post by Greg Le » Sat, 01 Jan 2005 13:22:07



> > coming from me.  It's fun, but so far it hasn't told me
> > anything I didn't know about my problem.
> Ah, but it has.  Without a sniffer, you have no way of knowing if
> packets are being sent and received.

When I first asked about this, I mentioned that I had used
netstat to determine that packets were being sent but not
received.

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1. ucd-snmpd snmp.conf remote access configuration.

Greetings.

I'm trying to use ucd-snmpd bundled with Linux 7.2. It loads fine
and I can do mib walks and gets no problem but snmpset
doesn't work.

If I have a remote host lets say.. 192.168.181.50 and I want
my agent to let it have complete access what would be be the
line on snmp.conf ?

I tried something like

com2sec local 192.168.181.50

without success.

thanks for any help.

Javier.

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