Re: SNMP Informs sent from snmpd do not work if firewall is enabled on the machine
Xiang Li <[email protected]>
| Newsgroups | gmane.network.net-snmp.user |
|---|---|
| Message-ID | <[email protected]> |
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
<http://www.net-snmp.org/docs/man/snmpcmd.html>(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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