[Nagiosplug-devel] [ nagiosplug-Bugs-1284352 ] check_dhcp -s not compatible with helpers/relays

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Bugs item #1284352, was opened at 2005-09-07 16:19
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Category: General plugin execution
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Greg Connor (nekodojo)
Assigned to: Nobody/Anonymous (nobody)
Summary: check_dhcp -s not compatible with helpers/relays

Initial Comment:
check_dhcp -s is supposed to verify that a response is
received from a certain server (or servers).  But, when
used with a dhcp relay agent (or an iphelper in Cisco
speak) the offer appears to come from the relay, not
the actual server which answered.

When the plugin is used with $HOSTADDRESS$ to target a
particular server, the reply comes from the
relay/forwarder and not from the dhcp server, so the
status will show an error even if the DHCP server we
want to test is up.

This can be worked around by testing the relays with -s
instead of the ip of the dhcp server.  However, if
there are multiple servers to be monitored and they are
not on the same network as the nagios server.  In that
case, the plugin will always report at least one answer
from each relay and the plugin can't tell if all the
dhcp servers are working.

The expected behavior is to use the IP from "siaddr" if
it is non-zero, which would indicate that the reply was
forwarded on behalf of a remote DHCP server.  (see diff
for a suggested fix)

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