[systemd-devel] inetd-style service with connection logging

[Brian Kroth]

Brian Kroth <bpkroth at gmail.com> 2016-06-22 13:48:
>On Jun 17, 2016 11:11, "Brian Kroth" <bpkroth at gmail.com> wrote:
>>
>> Mantas Mikulėnas <grawity at gmail.com> 2016-06-17 08:00:
>>>
>>> On Fri, Jun 17, 2016 at 5:05 AM, Brian Kroth <bpkroth at gmail.com> wrote:
>>>
>>>> Hi, I'm trying to convert an old school inetd service into a systemd
>>>> socket activation.
>>>>
>>>> More or less what was describe in [1] worked for me.  However, the bit
>I'm
>>>> currently missing is connection logging.
>>>>
>>>> With the openbsd-inetd package (Debian), one could enable libwrap style
>>>> logging with the -l option to inetd and get something like this:
>>>>
>>>> Jun 16 00:00:16 faitest32 inetd[16032]: connection from 10.130.105.148,
>>>> service nrpe (tcp)
>>>>
>>>> Anyone know how to do that with systemd socket/service pairs?  Does it
>>>> just require a ExecPreStart sort of rule to echo %i (or some such) into
>a
>>>> logger pipe (or whatever the journal equivalent of that is), or is
>there a
>>>> directive to get that that I'm just missing in my googling?
>>>>
>>>
>>> As of v209, the source address is *always* logged when the instance
>starts
>>>
>>> (well, technically, it's added to the service description) – search the
>>> journal for MESSAGE_ID=39f53479d3a045ac8e11786248231fbf. (Can't filter by
>>> unit unfortunately since UNIT= only has the unique name of the instance,
>>> not the generic one...)
>>>
>>> Jun 16 18:19:10 frost systemd[1]: Started OpenSSH Per-Connection Daemon
>>> ([fd80:56c2:e21c:288b:8199:931f:3a4e:cfb3]:56168).
>>> Jun 16 18:22:07 frost systemd[1]: Started OpenSSH Per-Connection Daemon (
>>> 10.114.14.18:60064).
>>> Jun 17 07:52:34 frost systemd[1]: Started Ident (RFC 1413) per-connection
>>> server ([::1]:50860).
>>
>>
>> Hmm, I'm running v215 on a Debian Jessie machine, but that MESSAGE_ID
>isn't turning anything up for the messages I was expecting.
>>
>> # journalctl --all -x | grep -i nrpe
>> ...
>> Jun 17 10:05:15 faitest64 systemd[1]:
>[/etc/systemd/system/nagios-nrpe-server at .service:25] Failed to parse nice
>priority, ignoring: $NICENESS.
>>
>> (from before I took that out from my other question thread)
>>
>>
>> # journalctl MESSAGE_ID=39f53479d3a045ac8e11786248231fbf
>> -- Logs begin at Thu 2016-06-16 18:46:02 CDT, end at Fri 2016-06-17
>11:09:04 CDT. --
>> Jun 17 00:19:35 faitest64 systemd[886]: Reached target Paths.
>> Jun 17 00:19:35 faitest64 systemd[886]: Reached target Timers.
>> Jun 17 00:19:35 faitest64 systemd[886]: Reached target Sockets.
>> Jun 17 00:19:35 faitest64 systemd[886]: Reached target Basic System.
>> Jun 17 00:19:35 faitest64 systemd[886]: Reached target Default.
>> Jun 17 00:19:40 faitest64 systemd[886]: Reached target Shutdown.
>>
>>
>> Do you know the commit id for that change offhand?  Maybe Debian stripped
>the patch or something, though I'm not sure why that would have happened.
>>
>> Thanks,
>> Brian
>
>Anyone else have any other thoughts on the lack of inetd style connection
>logs?
>
>Thanks,
>Brian

Ah, I figured it out.  Our grub setup had the "quiet" keyword on the 
boot command line, and the version of systemd (v215) in Debian Jessie 
doesn't include the fix [2] for the issue described in [1].

Basically, there was a hard call to "log_set_max_level(LOG_NOTICE);" in 
the main systemd process while processing the kernel command line 
arguments, which happens after parsing the /etc/systemd/system.conf 
config file, so any LogLevel value set there (mine was explicitly set to 
LogLevel=info) is overwritten.  That wasn't documented so it took a 
while for me to find.

I'll submit a bug to Debian to request a backport of that fix, but in 
the meantime, in case anyone else runs into this, an alternative 
workaround for the meantime is to also include "systemd.log_level=info" 
in the kernel boot parameters (possibly after the "quiet" keyword).

Thanks,
Brian

[1] https://lists.freedesktop.org/archives/systemd-devel/2014-December/026271.html (commit 5e07a79e)
[2] https://lists.freedesktop.org/archives/systemd-devel/2015-February/027946.html (commit d7b15e0a)
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