[syslog-ng] syslog-ng 1.5.17 and tcp-keep-alive not working

Olaf Hoyer ohoyer at ohoyer.de
Thu Jun 16 16:21:57 CEST 2005

On Thu, 16 Jun 2005, Balazs Scheidler wrote:

>> Ahh, ok. makes sense. But how do I solve my problem, that, whenever the
>> syslog-ng on the loghost has to be restarted or other problems, that I
>> have to manually restart the syslog-ng on the client?
>> There are some scenarios, where on the loghost the syslog-ng does not
>> only get a SIGHUP, but might die and needs to be restarted, some admin
>> or startscript does a full stop/start etc.
>> So in that case it would be fine if the client can upon detection of a
>> terminated tcp connection try to re-establish it, therefore avoiding the
>> manual restart of syslog-ng on the client side.
>> How can this be solved?
> This is how it works. syslog-ng automatically reconnects if the
> connection is broken. 1.5.17 might not be perfect in this regard
> however, this functionality had some bugs in the past. (1.5.17 is a
> development release, 1.6.x is stable series)
Ahh, ok- I already assumed so. I would have liked to test against both 
1.6.x versions of syslog-ng, but because of being the one of them an 
embedded device, I could not test this with the concrete application.

It also looks like that on the loghost itself after stop/start of 
syslog-ng, the tcp socket enters FIN_WAIT_2, and on the client 
CLOSE_WAIT. After some time (I had to wait several minutes, will do some 
timing measurements later, to check for the CLOSE_WAIT timeout) I sent 3 
messages, the first 2 got lost, the third arrived. So the session has 
been reestablished as it should, and some data has been lost, which also 
was foreseeable.

Hmm, I'll make some timing tests and will post the results...

Thanks a lot

Olaf Hoyer        ohoyer at ohoyer.de
Fuerchterliche Erlebniss geben zu raten,
ob der, welcher sie erlebt, nicht etwas Fuerchterliches ist.
(Nietzsche, Jenseits von Gut und Boese)

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