[BALUG-Admin] "all better now": Re: ns0.balug.org refusing AXFR request from ns1.linuxmafia.com, zone balug.org

[Michael Paoli]

Thanks for catching that.
Should be "all better now".

Apparently was "operator error" (me) 8-O ...
I shouldn't ought be trying to pay attention to & do multiple important
things at the same time (was on relatively long non-trivial phone
call, while also doing unrelated Linux sysadmin activities at same
time ... what could possibly go wrong?  Well ...).
W evening, I accidentally took down network interface on
incorrect system (intended to do it on an unrelated virtual
machine, but inadvertently did so on the physical host (oops!),
which also had implications for other virtual machines (notably
balug) on same physical host.  Went about working to correct that,
and after some futzing about, got all the interfaces and networking
stuff squared away again ... but alas, I forgot to check bind9 (and
potentially other services too).
For better and/or worse, bind9 is pretty good at dropping privilege.
Unfortunately this also causes bind to - at least mostly - stop
listening on interfaces (or at least IPv4 IPs) that go away ... even
if/when they come back ... at least typically without a reload or the like.
I may have done a reload, but in any case, didn't check.  And, with whatever
happened in this particular case, reload wasn't sufficient to get bind also
listening on TCP on the primary Internet facing IPv4 IP address ...
(the interface didn't merely drop IPs, but was taken fully down and
away and brought back - in part of the earlier troubleshooting/correction
process), a restart of bind9 did, however resolve the listening issue -
and seems things to be "all better now".

I ought put some more proper monitoring in place - one of many things on
the todo list.  I'm more likely to do that after I upgrade my
relevant Debian oldstable installations to stable (by adding the
monitoring after such upgrade, that's one less set of custom configurations
needing review and possibly upgrades going through major OS version upgrade).

> From: "Rick Moen" <rick@linuxmafia.com>
> To: balug-admin@lists.balug.org
> Cc: Michael Paoli <Michael.Paoli@cal.berkeley.edu>
> Subject: ns0.balug.org refusing AXFR request from  
> ns1.linuxmafia.com, zone balug.org
> Date: Fri, 17 Jan 2020 00:37:18 -0800

> Nameserver ns0.balug.org responds to ping, responds to DNS queries,
> _but_ refuses AXFR request for zone balug.org from slave nameserver
> ns1.linuxmafia.com.  (Below mail from logcheck shows the first
> appearance of refusal in the logs; this behaviour is still ongoing.)
>
> [rick@linuxmafia]
> ~ $ dig -t axfr balug.org @96.86.170.229
> ;; Connection to 96.86.170.229#53(96.86.170.229) for balug.org failed:
> connection refused.
> [rick@linuxmafia]
> ~ $
>
> ----- Forwarded message from logcheck system account  
> <logcheck@linuxmafia.com> -----
>
> Date: Thu, 16 Jan 2020 12:02:01 -0800
> From: logcheck system account <logcheck@linuxmafia.com>
> To: root@linuxmafia.com
> Subject: linuxmafia.com 2020-01-16 12:02 System Events
>
> System Events
> =-=-=-=-=-=-=
> Jan 16 11:33:15 linuxmafia named[4620]: client 96.86.170.229#6229:  
> received notify for zone 'balug.org'
> Jan 16 11:33:15 linuxmafia named[4620]: zone balug.org/IN: Transfer started.
> Jan 16 11:33:15 linuxmafia named[4620]: transfer of 'balug.org/IN'  
> from 96.86.170.229#53: failed to connect: connection refused
> Jan 16 11:33:15 linuxmafia named[4620]: transfer of 'balug.org/IN'  
> from 96.86.170.229#53: Transfer completed: 0 messages, 0 records, 0  
> bytes, 0.028 secs (0 bytes/sec)
>
>
> ----- End forwarded message -----