[Dnsmasq-discuss] Incorrect broadcast address given

OB Lutz ob.lutz at gmail.com
Tue Oct 14 02:24:48 BST 2008


I'll get that output tomorrow. When multiple routers are in the
network, there will be routes to other sets of ips, like
182.168.8.1/27 going out the wireless (ath0), but theres never another
route to 192.168.8.224/27. A default route is only present when
another router is setup as an internet gateway. This output was from a
router isolated from the rest of the mesh network (it was on a
different wireless channel). The problem exists both when the router
is alone or when its talking to its brethren, so I chose the isolated
version to make everything as simple as possible.

On Mon, Oct 13, 2008 at 9:11 PM, richardvoigt at gmail.com
<richardvoigt at gmail.com> wrote:
> On Mon, Oct 13, 2008 at 2:23 PM, OB Lutz <ob.lutz at gmail.com> wrote:
>> My routing table:
>> # route
>> Kernel IP routing table
>> Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
>> 192.168.8.224   *               255.255.255.224 U     0      0        0 br-lan
>> 224.0.0.0       *               240.0.0.0       U     0      0        0 bmf0
>>
>> Nothing ambiguous there. olsr adds routes going out the wireless
>> interfaces when appropriate. iptables just forwards olsr traffic
>> between wireless interfaces. Routes are clearly defined
>
> Not entirely sure, but I think your routing table is probably too
> complex for the "route" tool to handle, since it didn't find a default
> route or any external routes whatsoever.  Do you have the iproute2
> toolkit, can you use "ip route show" instead of "route"?
>
> Especially since you mentioned single-stepping through the dnsmasq
> code that sets the broadcast address and it matching on multiple
> iterations of the loop.  There's more going on than "route" is showing
> you.
>
>>
>> On Sat, Oct 11, 2008 at 9:15 AM, richardvoigt at gmail.com
>> <richardvoigt at gmail.com> wrote:
>>> On Wed, Oct 8, 2008 at 1:41 PM, OB Lutz <ob.lutz at gmail.com> wrote:
>>>> The routing is fine. All the eth*s are bridged to br-lan, which is
>>>> given 192.168.8.225/27 (255.255.255.224). ath0 is 192.168.8.226/27,
>>>> ath1 192.168.8.227/27. iptables rules take care of forwarding
>>>> appropriate traffic around. Routing is not an issue.
>>>
>>> That's not fine.  Routing should never be done with iptables rules, it
>>> should be done with the kernel routing table.  And a particular subnet
>>> needs to correspond to a bridging (L2 forwarding) domain.  Right now
>>> your route to 192.168.8.224/27 is ambiguous.
>>>
>>> Fix your IP address assignment and dnsmasq is going to work properly.
>>> Dnsmasq reads information from the kernel routing table, if you've got
>>> invalid information in there because you're overriding routing with
>>> iptables, you can't expect it to work.
>>>
>>> And as far as your thought that dhcp is dhcp and routing is routing
>>> and never the twain shall meet, the broadcast address is routing.
>>> Dnsmasq has to give it out.  So your nice idea of separation breaks
>>> down.
>>>
>>
>



More information about the Dnsmasq-discuss mailing list