[Dnsmasq-discuss] [FEAT.REQ] Further localisation of --localise-queries

[Alex Hermann]

Luca Landi wrote:
> Alex Hermann ha scritto:
> 
>>On Sunday 01 May 2005 14:19, Luca Landi wrote:
>>
>>>Alex Hermann ha scritto:
>>>
>>>>>>server: eth0 192.168.1.1 <---> client1 : 192.168.1.101
>>>>>>        eth1 192.168.1.2 <---> client2 : 192.168.1.102
>>>>>>        eth2 192.168.1.3 <---> client3 : 192.168.1.103
>>>>>>        eth3 public ip   <---> inet
>>>
>>>[...]
>>>if you want your server to play the role of the switch then all you have 
>>>to do is to bring up a bridge interface, [...]
>>
>>Sadly enough, some things aren't possible with the (linux) bridging code. 
>>My connections are a horrible mix of Gbit, 100Mbit, 10Mbit and wifi. To 
>>get the max out of the Gbit connection I need a high MTU on that iface. 
>>The bridging code doesn't support a MTU other than 1500 at all (or just 
>>not across different bandwidth devices). Also, there seem to be some more  
>>problems with my nics and bridging that need some further investigation. 
> 
> 
> Ok, I see.
> 
> So, to go back to your original question, did you try to run three different 
> instances of dnsmasq, each serving only one IP address, where two of them 
> serve only DNS requests and the third one serves both DNS and DHCP? this 
> way you can configure each dnsmasq instance to read a different "hosts" 
> file while at the same time keep DHCP centralised. Having different "hosts" 
> files let you fine tune which static IP addresses get sent to your clients. 
> Basically the whole thing shoud look like this:
> 
> dnsmasq -a 192.168.1.1 -H /etc/hosts1 -h -F <your-DHCP-range-of-addresses>
> dnsmasq -a 192.168.1.2 -H /etc/hosts2 -h
> dnsmasq -a 192.168.1.3 -H /etc/hosts3 -h

That would need a separate instance for the DHCP service, otherwise it will 
only listen on one interface.

> I only thought it and didn't try it but to me looks like it may work fine. 
> The only remaining issue might be the '-h' option, which is needed to 
> prevent dnsmasq from reading the main /etc/hosts file. If you have no 
> common static hostnames to serve then I think you should be fine, else I'm 
> afraid you'd have to duplicate the common static hostnames into the other 
> three "hosts" files.

For the common static names, the --addn-hosts option can be used.

This scheme might actually work acceptable, and I will try it. One issue might 
be memory consumption when I need multiple instances of dnsmasq, each having a 
hosts file of over 500kB in memory (ad-server redirects).

The fallback option will be using separate subnets.

Thanks for the hints,


Alex.