Bug #1408
closed
DHCP DNS servers still get routes even if allow override is unchecked
Added by Jim Pingle over 13 years ago.
Updated over 13 years ago.
Affected Architecture:
All
Description
If you have hardcoded DNS servers and uncheck "Allow DNS server list to be overridden by DHCP/PPP on WAN", DNS servers assigned by the DHCP server on a WAN are still given routes even if they are not added as system DNS servers.
Easy to reproduce by adding some DNS servers, unchecking the option, and then watching the routing table. The DNS server(s) assigned by the DHCP WAN show up in the routing table with a MAC (not an IP) as the gateway.
This is caused by the dhclient script.
I do not think this should be fixed for 2.0 as this has been the behavior until now.
What is the issue it causes?
Seems like a pretty bad bug if you checked the option to ignore the DNS servers and yet they get static routes. I'd prefer to see a fix in 2.0, I don't think anyone would expect or have been relying on this misbehavior.
The problem I had with it is that I wanted to route 8.8.4.4 over my DSL, and had set the GUI to do just that. However, my Cable provider started handing out 8.8.4.4 as a DNS server over DHCP, so dhclient added a route to 8.8.4.4 over Cable, even though the GUI was set to route that over DSL. This led to an inconsistency in the GUI such that I chose to do two specific things (route this IP one way, and disallow override) neither of which really happened as expected.
I worked around it by flipping the WANs I had assigned for each of those servers, but if my cable provider starts handing out 8.8.8.8 as a DNS server too then I'll be stuck again and have to pick another DNS server, since dhclient isn't honoring the "do not override" setting.
- Status changed from New to Feedback
- Status changed from Feedback to Resolved
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Updated by Ermal Luçi 
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