[Dnsmasq-discuss] IP range with 0.0.0.0 netmask?

Simon Kelley simon at thekelleys.org.uk
Wed Oct 30 12:44:41 GMT 2013


On 28/10/13 10:57, Andrea Galvani wrote:
> Hello everyone.
>
> I'm working on a particular network architecture which allows a host to
> have any address inside of a network (that is, not only private
> addresses!). The host is not directly reachable, and every connection
> with the host is managed by the router above the network with an ad-hoc
> protocol, which is not the matter here.
>
> Since every host has a fixed IP, I'm using dnsmasq for storing static
> leases for every host in the network.
> For now I've been using only 10.0.0.0/8 addresses, but my idea is to
> start using really "any" address possible (for example: 1.2.3.121).
>
> So, apart from the static leases, I configured dnsmasq like this:
>
> dhcp-range=wlan0,1.0.0.1,255.255.255.254,0.0.0.0,1h
>
> Every host should obtain his static IP, without any restriction (even
> outside of the 10.0.0.0/8 range).
> The range seems to be ok as dnsmasq boots:
>
> dnsmasq-dhcp[6180]: DHCP, IP range 1.0.0.1 -- 255.255.255.254, lease
> time 1h
>
> But as soon as I connect a host (which should obtain 1.2.3.121) I get
> this error as a result:
>
> dnsmasq-dhcp[6180]: no address range available for DHCP request via wlan0
>
> Is the range not accepted by dnsmasq?
> Is it really possible to configure dnsmasq in order to provide "any"
> address?
> Are there some constraints (for example, on the netmask) which I'm missing?
> If so, which is the biggest address pool that is possible to configure?
>


The reason it's behaving like that is that for a dhcp-range to be valid, 
the netmask has to equal the netmask of the interface where the  DHCP 
request arrived. I think it's unlikely that you have 0.0.0.0 as the 
netmask, and if you did, it would break routing anyway. That explains 
the problem: I don't think that there is a solution.


Cheers,
Simon



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