Red Hat Bugzilla – Bug 72487
RFE: Add support for disabling the duplicate IP check
Last modified: 2014-03-16 22:30:29 EDT
Description of Problem:
It would be useful in some situations, if it would be possible to disable
the duplicate IP check (or maybe warn about the situation but still
continue on). Also displaying the offending MAC address(es) would be useful.
Reason I need it is that my DSL runs PPPoE over some bridging LRE boxes
which means 192.168.0.1 etc. addresses might (and are) randomly get chosen by
some other user. Horribly broken, I know, but forcing the address (and statically
setting the arp entries + filtering out outside crap based on mac addresses)
works just fine until I get another ethernet card, which is the only good solution
(or get the provider to configure their boxes correctly :) )
Solved this problem ages ago by getting another ethernet card, but
the feature still could be useful so here's a patch that does the trick
(a bit kludgy, I know, but my shell scripting is a bit rusty :-) ).
Actually the check as it is now is somewhat useless depending on how fast
the adapter gets the link up after a ifconfig ethX up, since the arping
queries end up in /dev/null. (same problem as with DHCP, which is why there is a
check_link_down before the dhcp client gets run).
For static addresses the extra delay required probably isn't worth it and
generally if the network is temporarily down and you have a static ip address,
you'd want things to automatically work when it does come back up.
You'd also want that users who don't know the difference between "IP address"
and "Router/DNS server IP address" can't DoS your router/DNS server when
it is booting (which is another scenario where the DUPLICATE_IP_CHECK=no
option might be useful, although on such "hostile" networks switch port locking
is the way to go ;) ).
Created attachment 95489 [details]
Patch to allow disabiling the duplicate IP check and show offending MAC address
The patch makes sense. Bill, any objections to having this patch
merged this bug week? There appears to be zero risk in applying the
patch, since behaviour only changes if the system is configured for
a) magic config setting
b) non-translatable output string
Created attachment 109755 [details]
Updated version of the original patch
This still has a magic config setting, but this time it's documented and the
string is translatable.
I just ran across this while setting up LVS with "direct routing." Any chance
of getting this, along with another option to disable the later call to arping,
in? If so, I'll gladly work up a patch.
Bill-what are your thoughts on this... patch is attached
I think that this functionality is already included