[Dnsmasq-discuss] Simplest working "shared-network" configuration?

[Paul Gear]

On 10/7/21 9:52 pm, Geert Stappers via Dnsmasq-discuss wrote:
> On Sat, Jul 10, 2021 at 05:57:40PM +1000, Paul Gear wrote:
>> On 10/7/21 5:13 pm, john doe wrote:
>>> On 7/10/2021 7:58 AM, Paul Gear wrote:
>>>> Hi all,
>>>>
>>>> It's been a while since I originally posted about this, and I've done a
>>>> lot of experimenting without landing on a working setup.
>>>>
>>>> I'm trying to get a very simple test case working, where I have a 
>>>> number
>>>> of vnet interfaces, all configured with the link-local address
>>>> 169.254.0.1/16, and have dnsmasq allocate the leases out of a different
>>>> range (in this case, I'm using a portion of the documentation prefix,
>>>> 203.0.113.0/29).  Here's my configuration:
>>>>
>>>> pid-file=/var/lib/dnsmasq-vnet/dnsmasq-vnet.pid
>>>> bind-dynamic
>>>> interface=vnet*
>>>> log-dhcp
>>>> no-hosts
>>>> dhcp-range=203.0.113.0, 255.255.255.248, 1d
>>> From (1):
>>>
>>> " this dhcp-range MUST include the netmask."
>>>
>>> Unless I'm missing something, I don't see a subnet mask being specified.
>>>
>>>
>>> 1)  https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html
>>
>> Hi John,
>>
>> Unless I'm missing something 255.255.255.248 is a netmask, and dnsmasq
>> doesn't appear to support CIDR notation in dhcp-range specifications.  At
>> least, when I attempt to use /29 instead, it fails to start, saying:
>>
>> dnsmasq: bad dhcp-range at line 41 of /var/lib/dnsmasq-vnet/dnsmasq.conf
> Snippet dnsmasq manual page
>
> --dhcp-range=[tag:<tag>[,tag:<tag>],][set:<tag>,]<start-addr>[,<end-addr>|<mode>][,<netmask>[,<broadcast>]][,<lease 
> time>]
>
> So
>>>> dhcp-range=203.0.113.0, 255.255.255.248, 1d
> should be something like
> } } } dhcp-range=203.0.113.0, 203.0.113.7,255.255.255.248, 1d
>
>
> Back to
>>> From (1):
>>>
>>> " this dhcp-range MUST include the netmask."
>>>
>>> Unless I'm missing something, I don't see a subnet mask being specified.
>>>
>>>
>>> 1)  https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html
>>>
> If so, the
> --dhcp-range=[tag:<tag>[,tag:<tag>],][set:<tag>,]<start-addr>[,<end-addr>|<mode>][,<netmask>[,<broadcast>]][,<lease 
> time>]
> should be
> --dhcp-range=[tag:<tag>[,tag:<tag>],][set:<tag>,]<start-addr>[,<end-addr>|<mode>],<netmask>[,<broadcast>][,<lease 
> time>]
> or even
> --dhcp-range=[tag:<tag>[,tag:<tag>],][set:<tag>,]<start-addr>,<end-addr>|<mode>,<netmask>[,<broadcast>][,<lease 
> time>]

Hi John & Geert,

So bottom line is that end-addr is not optional when netmask is 
specified, even though a literal reading of the current man page 
suggests that it is.  I'll try to get a documentation patch together(is 
here the right place to post it?) when I'm done.

That one little change was enough to turn my basic test case into a 
fully working setup.  Thanks for your help.

Regards,
Paul