Re: SNMP Informs sent from snmpd do not work if firewall is enabled on the machine

I tried giving a clientaddr entry but looks like it ignores the port
and still uses an available port when sending out notifications.

-Datta.

On Sat, Jun 4, 2011 at 4:45 AM, Xiang Li <[email protected]> wrote:
>
> On 6/1/2011 10:58 PM, Dattaram Porob wrote:
>
> In case of a v2 inform, the Inform message is sent by the agent
> (net-snmp 5.6.1) and received by the receiver but the ACK sent by the
> receiver does not reach the agent since it is blocked by the firewall.
> This results in the agent sending the Inform message again (n times
> depending on the number of retries configured) and so there are
> duplicate Informs at the receiver.
> In case of a v3 Inform, before sending the actual Inform message, the
> agent tries to discover the engineId of the receiver. The response to
> the discover is not received by the agent and so it is not be able to
> send out the Inform message itself.
> We are using 'iptables' as the firewall on the linux machine where the
> agent is running. The problem is that the Inform response is always on
> a different UDP port, so it is not possible to configure a specific
> port to allow incoming traffic.
>
> You can try using  'clientaddr' to force traps using a fixed local port.
> snmp.conf
>
> clientaddr [<transport-specifier>:]<transport-address> specifies the source
> address to be used by command-line applications when sending SNMP requests.
> See snmpcmd(1) for more information about the format of addresses.
> This value is also used by snmpd when generating notifications.
> This way, it is  possible to configure a specific port to allow incoming
> traffic.
>
>
>
>
>
> --
> Xiang Li
> http://www.champnms.com

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