[Dnsmasq-discuss] 2.53rc2

[Simon Kelley]

clemens fischer wrote:
> clemens fischer wrote:
> 
>> 2010-05-27_16:07:11.54045 socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 7
>> 2010-05-27_16:07:11.54059 setsockopt(7, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
>> 2010-05-27_16:07:11.54073 bind(7, {sa_family=AF_INET,
>>  sin_port=htons(53), sin_addr=inet_addr("0.0.0.0")}, 16) = -1 EADDRINUSE
>>  (Address already in use)
>> 2010-05-27_16:07:11.54092
>> 2010-05-27_16:07:11.54110 dnsmasq: failed to create listening
>>  socket: Address already in use
> 
> I forgot to mention this:
> 
>   except-interface=nic0
>   except-interface=nicI
>   except-interface=lo
>   no-dhcp-interface=nic0
>   no-dhcp-interface=nicI
>   no-dhcp-interface=lo
> 
> With these settings and "--interface=x --bind-interfaces" on the command
> line, I still get:
> 
>   dnsmasq 16293 nobody 5u IPv4 60646 0t0 UDP *:67
>   dnsmasq 16293 nobody 6u IPv6 60660 0t0 TCP [fe80::21f:1fff:fe52:9dbd]:53 (LISTEN)
>   dnsmasq 16293 nobody 7u IPv6 60661 0t0 UDP [fe80::21f:1fff:fe52:9dbd]:53
>   dnsmasq 16293 nobody 8u IPv4 60662 0t0 TCP 192.168.3.1:53 (LISTEN)
>   dnsmasq 16293 nobody 9u IPv4 60663 0t0 UDP 192.168.3.1:53
> 
> I expected dnsmasq to bind 192.168.3.1:67 instead of *:67.  This is no
> problem in my situation, but what happens when I need to use a dhcp
> relay?
> 

Binding 192.168.3.1:67 means that packets from unconfigured hosts which
are sent to 255.255.255.255:67 have problems on some platforms.

If you set --bind-interfaces then dnsmasq will set the SO_REUSEADDR flag
on that socket, which allows you to run a relay which also listens on
*:67, as long as it also sets that flag.

On my list is to add a command-line option to dhcp-helper to do exactly
that.


Cheers,

Simon.