Re: SNMP

[Jeremy Winder <jwinder@logicalsi.com>]

This is going to be an interesting project. The first problem is snmp
works on gets and sets. So you either get an object's value or you set
and object's value. You can not do both in the same operation. In your
example, you will need to setup an object that you can set the IP
address you want arped to. Then you need to setup an object that you can
get the results back from. To have box B arp 10.0.0.1, you would do a
two step operation. First a snmpset REMOTEARP-OID 10.0.0.1, then a
snmpget REMOTEARP-OID.

Make sense? I hope so. I'm not completely awake yet this morning.

For the get part you could use the NET-SNMP-EXTEND-MIB, I suggest google
for examples. As for the set part, I'm not going to be much help as I've
not done it.

Another, option would be to walk the arp table OID
(IP-MIB::ipNetToPhysicalPhyAddress) and look for your IP address.
However, if machine B hasn't talked to the IP in awhile, it may not be
in the arp table anymore. Also, during a quick test I found it takes
Linux a minute or so between when a new address enters the arp table and
when it is exposed via snmp. So your mileage my vary.

Hope this helps,

Jeremy

On Wed, 2009-03-25 at 14:13 +0200, Alex wrote:
> Hi, i want to run a script just interrogating a specific OID defined by
> me, to be more specific i have two boxes A and B,
> from box A i want to use snmpwalk to trigger a script which will run
> arping on  box B that's simple but i want to pass the ip which i want to
> arping via  snmpwalk from box A, does anywone have a clue how can i do this?
> 
>