Re: [Dnsmasq-discuss] Different behaviour with "interface=" on two almost identical systems

2024-03-30 Thread Chris Buechler
On Sat, Mar 30, 2024 at 4:39 AM Chris Green  wrote:
>
> On Fri, Mar 29, 2024 at 03:45:20PM -0500, Chris Buechler wrote:
> >On Thu, Mar 28, 2024 at 11:40 AM Chris Green <[1]c...@isbd.net> wrote:
> >
> >  I did try stopping dnsmasq and then nothing was listening on port
> >  53.
> >  However, just to prove it:-
> >  root@backup:~# ss -tulpn sport = 53
> >  Netid State  Recv-Q Send-Q Local Address:Port  Peer Address:Port
> >  Process
> >  udp   UNCONN 0  0[2]0.0.0.0:53
> >  0.0.0.0:* users:(("dnsmasq",pid=1826,fd=4))
> >  udp   UNCONN 0  0   [::]:53[::]:*
> >   users:(("dnsmasq",pid=1826,fd=6))
> >  tcp   LISTEN 0  32   [3]0.0.0.0:53
> >  0.0.0.0:* users:(("dnsmasq",pid=1826,fd=5))
> >  tcp   LISTEN 0  32  [::]:53[::]:*
> >   users:(("dnsmasq",pid=1826,fd=7))
> >
> >That's the nature of how dnsmasq binds by default. You need two config
> >lines to actually bind only to localhost:
> >listen-address=127.0.0.1
> >bind-interfaces
> >The listen-address config will make it only reply to queries to
> >localhost, but doesn't prevent wildcard binding. bind-interfaces makes
> >it bind explicitly to the listen-address. See the bind-interfaces
> >section of the man page for details.
> >[4]https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html
> >
> OK, thank you, I did read those man page entries but found it rather
> confusing!  It has fixed the problem though! :-)
>
> I still don't quite understand why it seemed to work on one system but
> not on another almost identical one.

Glad that worked for you. The difference is likely either the other
system already had bind-interfaces in its config somewhere so it's not
binding wildcard, or otherwise has a host firewall blocking port 53 if
it is wildcard binding.

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Re: [Dnsmasq-discuss] Different behaviour with "interface=" on two almost identical systems

2024-03-30 Thread Chris Green
On Fri, Mar 29, 2024 at 03:45:20PM -0500, Chris Buechler wrote:
>On Thu, Mar 28, 2024 at 11:40 AM Chris Green <[1]c...@isbd.net> wrote:
> 
>  I did try stopping dnsmasq and then nothing was listening on port
>  53.
>  However, just to prove it:-
>  root@backup:~# ss -tulpn sport = 53
>  Netid State  Recv-Q Send-Q Local Address:Port  Peer Address:Port
>  Process
>  udp   UNCONN 0  0[2]0.0.0.0:53
>  0.0.0.0:* users:(("dnsmasq",pid=1826,fd=4))
>  udp   UNCONN 0  0   [::]:53[::]:*
>   users:(("dnsmasq",pid=1826,fd=6))
>  tcp   LISTEN 0  32   [3]0.0.0.0:53
>  0.0.0.0:* users:(("dnsmasq",pid=1826,fd=5))
>  tcp   LISTEN 0  32  [::]:53[::]:*
>   users:(("dnsmasq",pid=1826,fd=7))
> 
>That's the nature of how dnsmasq binds by default. You need two config
>lines to actually bind only to localhost:
>listen-address=127.0.0.1
>bind-interfaces
>The listen-address config will make it only reply to queries to
>localhost, but doesn't prevent wildcard binding. bind-interfaces makes
>it bind explicitly to the listen-address. See the bind-interfaces
>section of the man page for details.
>[4]https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html
> 
OK, thank you, I did read those man page entries but found it rather
confusing!  It has fixed the problem though! :-)

I still don't quite understand why it seemed to work on one system but
not on another almost identical one.

-- 
Chris Green

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