[snmp] SNMP proxy - trap forwarding

[Birgit Arkesteijn]

Hi Sri,

I'm not sure I can answer all of your questions.

Trap v1 has property IpAddress, the equivalent in TrapPduv2 would be
snmpTrapEnterprise (see http://www.ietf.org/rfc/rfc3418.txt).

The javadoc documentation on class uk.co.westhawk.snmp.stack.TrapPduv2 
explains the Trap v2 requirements and has pointers to two of the RTFs:
  http://www.ietf.org/rfc/rfc3416.txt
  http://www.ietf.org/rfc/rfc3418.txt

TrapPduv2 requires:
- sysUpTime.0
- snmpTrapOID.0


> In this process, the Source of the trap is changed to my Server's IP
> address.

Don't you mean your change the 'destination' of the trap to your
Server's IP address?
In fact, you probably have to make sure the 'source' of the trap is the
original source and not the proxy.


I don't have experience with 1.3.6.1.6.3.18.1.3.0 (= snmpTrapAddress.0)
    "The value of the agent-addr field of a Trap PDU which
    is forwarded by a proxy forwarder application using
    an SNMP version other than SNMPv1.  The value of this
    object SHOULD contain the value of the agent-addr field
    from the original Trap PDU as generated by an SNMPv1
    agent."
but you could try.
However, the section in RFC 2576 relates to translating SNMPv1 traps to
SNMPv2 traps. This is not what you are doing. You are forwarding (not
translating) a SNMPv2 trap via a proxy.


I'm not up to speed with how a proxy works exactly.
Because you create a new trap PDU, the server will probably think the
trap comes from the proxy.

The question is, when your server receives a trap (v1 or v2) from your
proxy and checks where it came from, will it check
- the socket (or the datagram packet) 
- the PDU varbind list
?

You can change the PDU varbind list in the stack, however, you cannot
change the datagram's address in the stack. The later is part of the
transport layer, and outside the scope of the stack.

Hope the above helps.

Cheers, Birgit


On Thu, Apr 12, 2007 at 09:45:16AM -0500, Nookala, Sridevi (Sridevi) wrote:
> Dear westhawk team,
> 
> We use westhawk stack for northbound trap forwarding.
> 
> My server listens for traps from multiple agents.
> 
> Some forward v1 and some v2
> 
> My server acts as a proxy. I simply pass thru v1 / v2 traps to
> northbound destinations.
> 
> By pass thru I mean I make a new v1trappdu for incoming v1 and new v2
> trap pdu for incoming v2.
> 
> I copy the varbinds from in the incoming trap.
> 
> In this process, the Source of the trap is changed to my Server's IP
> address.
> 
> Folks /Customers at the northbound don't want to see the proxy ip
> address and want to see the actual agent address.
> 
> How can I achieve this with the stack ? westhawk api
> 
> I hope my question is clear
> 
> This is urgent and any response will be greatly valued and welcomed.
> 
> The platform is SUN solaris 9 and stack version is snmp 4.13
> 
> -thx,
> Sri


On Thu, Apr 12, 2007 at 11:23:10AM -0500, Nookala, Sridevi (Sridevi) wrote:
> Dear westhawk,
> 
> Can somebody also enlighten me if the application acting as a proxy
> forwarder should tag in additional varbinds other than those varbinds
> that came in the original trap.
> 
> Any links/pointers to RFC's would be great
> 
> -thx,
> Sri


On Thu, Apr 12, 2007 at 12:25:40PM -0500, Nookala, Sridevi (Sridevi) wrote:
> Dear westhawk,
> 
> I was reading google and if an application is acting as a proxy and
> forwarding traps looks like it needs to tag/append extra varbinds with
> the actual remote agent information from RFC2576-MIB
> 
> Extra oid  .1.3.6.1.6.3.18.1.3.0
> 
> This  oid will take the value of the actual remote agent address
> 
> This is especially when proxying v2 traps.
> 
> I need confirmation from SNMP experts on if we should be tagging this
> extra information
> 
> Thanks and waiting for your response
> 
> Sri


On Thu, Apr 12, 2007 at 02:31:33PM -0500, Nookala, Sridevi (Sridevi) wrote:
> Dear westhawk,
> 
> I want to be more precise.
> 
> I have a sender (S1) sending traps to R1( receiver 1)
> 
> R1 now has to send R2 ( a different receiver - difft host/port)
> 
> When I receive a trap from S1 sender, I get the srcIP out of the
> incoming trap.
> 
> If it's a v1 trap that S1 sent, I can use OneTrapPduv1 and call
> setIpAddress to set the IP address.
> 
> If it's a V2 trap, how do I explicitly or do I have a way to explicitly
> specify the SRC IP.
> 
> In my case, when R1 has to forward to R2 from R1 (sun machine), I need
> to put the ipaddress of the actual sender S1
> 
> -thx,
> 
> Any help is really appreciated
> Sridevi

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-- Birgit Arkesteijn, birgit at westhawk.co.uk,
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