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

[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]cl at isbd.net> wrote:
> 
>      I did try stopping dnsmasq and then nothing was listening on port
>      53.
>      However, just to prove it:-
>      root at 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