[Dnsmasq-discuss] How to NOT bind dnsmasq to lo?

[Tim Tassonis]

On 7/10/24 22:52, Sven Geuer wrote:
> Hi Tim,
> 
> On Wed, 2024-07-10 at 21:55 +0200, Tim Tassonis wrote:
>> Hi all
>>
>> I tried using dnsmasq as local resolver, which in general works fine.
>>
>> However, I however would like to run a second instance of dnsmasq
>> binding only to a tap0, for a virtual network (vde2) for some qemu
>> virtual machines, and I can't seem to get that to work, as it always
>> complains about 127.0.0.1 already being taken.
>>
>> I tried:
>>
>>
>> DHCP_OPT="192.168.8.9,192.1688.8.99,255.255.255.0,192.168.8.255,8h"
>> dnsmasq --log-queries --user=dnsmasq \
>>           --dhcp-leasefile=/var/lib/misc/qemu-vde-dnsmasq.leases \
>>           --dhcp-range=$DHCP_RANGE \
>>           --listen-address=192.168.8.1 \
>>           --interface=tap0 --except-interface=lo \
>>           --domain=decentral.ch \
>>           --enable-tftp  \
>>           --dhcp-boot=/var/lib/qemu-vde/pxeboot/pxelinux.0 \
>>           --pid-file=/run/qemu-vde-dnsmasq.pid
>>
>>
>>
>> This works fine, but only if the local dnsmasq is not started.
>>
>> Otherwise, it will fail with:
>>
>> dnsmasq: failed to create listening socket for 127.0.0.1: Address
>> already in use
>>
>> Any ideas?
> 
> Looks like --bind-interfaces is missing from your configuration. I
> would also recommend to drop --interface and --except-interface, and
> only keep --listen-address.
> 
> Please re-read the manual page:
> 
> 
> -i, --interface=<interface name>
>     Listen only on the specified interface(s). Dnsmasq automatically
>     adds the loopback (local) interface to the list of interfaces to use
>     when the --interface option is used. [...]
> 
> -a, --listen-address=<ipaddr>
>     Listen on the given IP address(es). Both --interface and --listen-
>     address options may be given, in which case the set of both
>     interfaces and addresses is used. Note that if no --interface option
>     is given, but --listen-address is, dnsmasq will not automatically
>     listen on the loopback interface. To achieve this, its IP address,
>     127.0.0.1, must be explicitly given as a --listen-address option.
>     
> -z, --bind-interfaces
>     On systems which support it, dnsmasq binds the wildcard address,
>     even when it is listening on only some interfaces. [...] Setting
>     this option also enables multiple instances of dnsmasq which provide
>     DHCP service to run in the same machine.
>     
> Hope this helps,

Yes, the --bind-interfaces did the trick, thank you very much!


Bye
Tim