netstat showing multiple lines for each listening socket

[Ondřej Surý]

That's correct.

Since BIND 9.16, `named` binds to individual addresses instead of "any" because
it needs to send responses back from the same address and it's just easier this way.

Cheers,
--
Ondřej Surý (He/Him)
ondrej at isc.org

My working hours and your working hours may be different. Please do not feel obligated to reply outside your normal working hours.

> On 8. 7. 2024, at 10:52, Thomas Hungenberg via bind-users <bind-users at lists.isc.org> wrote:
> 
> Hello,
> 
> we have been running some BIND nameservers on Debian-based systems for many years.
> 
> Until (including) Debian 10 with BIND 9.11.5, netstat always showed only one line
> per listening socket, e.g.
> 
> tcp        0      0 10.x.x.x:53             0.0.0.0:*               LISTEN      1234/named
> tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN      1234/named
> udp        0      0 10.x.x.x:53             0.0.0.0:*                           1234/named
> udp        0      0 127.0.0.1:53            0.0.0.0:*                           1234/named
> 
> 
> We noticed that with Debian 11 and 12 (BIND 9.16.48 / 9.18.24), netstat instead
> shows multiple (on some systems four, on others up to 20) completely identical lines
> for each listening socket, like this:
> 
> tcp        0      0 10.x.x.x:53             0.0.0.0:*               LISTEN      1234/named
> tcp        0      0 10.x.x.x:53             0.0.0.0:*               LISTEN      1234/named
> tcp        0      0 10.x.x.x:53             0.0.0.0:*               LISTEN      1234/named
> tcp        0      0 10.x.x.x:53             0.0.0.0:*               LISTEN      1234/named
> tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN      1234/named
> tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN      1234/named
> tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN      1234/named
> tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN      1234/named
> udp        0      0 10.x.x.x:53             0.0.0.0:*                           1234/named
> udp        0      0 10.x.x.x:53             0.0.0.0:*                           1234/named
> udp        0      0 10.x.x.x:53             0.0.0.0:*                           1234/named
> udp        0      0 10.x.x.x:53             0.0.0.0:*                           1234/named
> udp        0      0 127.0.0.1:53            0.0.0.0:*                           1234/named
> udp        0      0 127.0.0.1:53            0.0.0.0:*                           1234/named
> udp        0      0 127.0.0.1:53            0.0.0.0:*                           1234/named
> udp        0      0 127.0.0.1:53            0.0.0.0:*                           1234/named
> 
> 
> We wonder what is causing this and if this is intended behaviour?
> 
> 
>   - Thomas
> 
> -- 
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