[Nagiosplug-devel] Feature request: extend check_ping to specify source address

[John P. Rouillard]

In message <488044D7.1070001 at op5.se>,
Andreas Ericsson writes:
>Dave Horsfall wrote:
>> On Thu, 17 Jul 2008, Matthias Eble wrote:
>>> this feature is already provided by check_icmp.
>> Err, how?
>It isn't, and I fail to see how that could work at all.
>
>check_icmp and ping alike mark their packets with pid, sequence-number,
>host-id (decided internally) etc, etc. Modifying the ip->src_addr field
>would cause the targeted host to send its ICMP_ECHO_REPLY packets to a
>different host, so check_icmp (or ping) wouldn't be able to pick them
>up at a later time.

Well you set the source address to one of the ip addresses on the box.

>Otoh, it's not hard to implement, so convince me it's needed and I'll
>add it :-)

I don't have any systems like this now, but imagine a multihomed host
on a routed network.

One interface at ip 1.1.1.2 allows direct access to the host 1.1.1.4,
while interface B on 2.2.2.2 allows access to 1.1.1.4 via some set of
routers starting with 2.2.2.1.

Unless you can set the source address, (which I assume also selects
the network interface the ping goes out), you have no way to test the
connectivity to the 1.1.1.1 network from the 2.2.2.2 box via the
routers starting at 2.2.2.1.

--
				-- rouilj
John Rouillard
===========================================================================
My employers don't acknowledge my existence much less my opinions.