[syslog-ng] Broken TCP connection

Zoltán Pallagi pzolee at balabit.hu
Tue Jan 12 21:17:34 CET 2010


Hi,

Yes, it is. You need to increase log_fetch_limit() and log_fifo_size() 
in this case. Keep your mind the log_fifo_size must be larger than the 
log_fetch_limit.
I don't suggest reducing flush_timeout but you should increase both 
flush_timeout and flush_lines. Because this message (dropping message) 
means your client send messages too fast and the syslog-ng cannot be 
able to write them in time.
Back to the original problem, I don't have much idea the reason for 
disconnecting. Can you send me the tcpdump file?  I suspect the problem 
may be here in relation to high traffic.


2010.01.11. 21:49 keltezéssel, James Pirman írta:
> pzolee,
>
> The client happens to be a custom application, so I don't have a 
> client config, and flow control doesn't really apply on the client 
> side.  I was able to setup a test environment and recreated the 
> problem.  The message immediately before the disconnect message is the 
> following:
>
> <47>1 2010-01-11T14:36:40.239-06:00 server-04 syslog-ng 30082 - [meta 
> sequenceId="122761"] debug Destination queue full, dropping message; 
> queue_len='1000', mem_fifo_size='1000'
>
> I am guessing if I don't have flow control on the client side that I 
> need to play with the numbers to ensure that none of the buffers ever 
> get filled up.  Is this correct?
>
> Thanks again,
> Jim
>
>
> ------------------------------------------------------------------------
> Date: Thu, 7 Jan 2010 21:11:15 +0100
> From: pzolee at balabit.hu
> To: syslog-ng at lists.balabit.hu
> CC: jim_pirman at hotmail.com
> Subject: Re: [syslog-ng] Broken TCP connection
>
> 2010.01.07. 17:53 keltezéssel, James Pirman írta:
>
>     Yes, that is correct.  The 127.0.0.1 destination is actually my
>     own application.
>
> Ok
>
>
>     I just noticed today that the problem seems to be happening when
>     the amount of traffic increases.  Right now I am testing with
>     log_fetch_limit increased from 100 to 1000, and I added
>     log_fifo_size globally and set it to 50000.  I also decreased my
>     flush timeout from 100 to 10.  This appears to be helping and I
>     haven't dropped a connection since.  Does this seem like the
>     correct approach?
>
> I think, this is just a game with numbers but not the real reason for 
> this behaviour. If you have problem with large traffic, just write the 
> "flags(flow-control)" field into the right destination of your client 
> config.
> Answer me that I asked of you, please (client config and debug log)
>
>
>     Thanks,
>     Jim
>
>     ------------------------------------------------------------------------
>     Date: Thu, 7 Jan 2010 17:38:41 +0100
>     From: pzolee at balabit.hu <mailto:pzolee at balabit.hu>
>     To: syslog-ng at lists.balabit.hu
>     <mailto:syslog-ng at lists.balabit.hu>; jim_pirman at hotmail.com
>     <mailto:jim_pirman at hotmail.com>
>     Subject: Re: [syslog-ng] Broken TCP connection
>
>     Hi,
>
>     If I understand you correctly, you have three client/servers,
>     don't you?
>     client(.218) -> relay server(.198) -> local server on relay server
>     (127.0.0.1)
>
>     and the problem is that sometimes your relay server drops the
>     connection of client.
>
>
>     James Pirman írta:
>
>         Is there anyone that can help with this?  Is there any more
>         information that I need to provide in order for me to get
>         help? I've been dealing with for weeks and am starting to
>         think the only solution is to write my own server.
>
>         ------------------------------------------------------------------------
>         From: jim_pirman at hotmail.com <mailto:jim_pirman at hotmail.com>
>         To: syslog-ng at lists.balabit.hu <mailto:syslog-ng at lists.balabit.hu>
>         Date: Tue, 5 Jan 2010 11:22:36 -0600
>         Subject: [syslog-ng] Broken TCP connection
>
>         I am currently having an issue with syslog-ng 3.0.4 where my
>         TCP connection between my client and server is lost throughout
>         the day.  By looking at the pcap file from tcpdump I can tell
>         that the TCP connection reset was initiated by the syslog-ng
>         server.  The only information that was initially in the log
>         file regarding this disconnection was the following 2 lines:
>
>         <45>1 2010-01-05T10:29:32.323-06:00 server-db-01 syslog-ng
>         29213 - [meta sequenceId="2733719"] notice Syslog connection
>         closed; fd='9', client='AF_INET(192.168.27.218:46326)',
>         local='AF_INET(192.168.27.198:20514)'
>
>     Can you show me the previous few lines before this log message?
>     Because if syslog-ng drops the connection usually sends log
>     message about the reason of this behaviour, like this:
>
>     2010-01-07T17:24:48+01:00 syslog-ng err Invalid frame header;
>     header=''
>     2010-01-07T17:24:48+01:00 syslog-ng notice Syslog connection
>     closed; fd='10', client='AF_INET(10.100.20.1:33251)',
>     local='AF_INET(10.30.0.32:20514)'
>
>
>     Your client config can also be useful, the problem may be on
>     client side. Can you show me the debug log of your client when the
>     connection lost?
>
>
>         and
>
>         <46>1 2010-01-05T10:29:32.323-06:00 server-db-01 syslog-ng
>         29213 - [meta sequenceId="2733720"] info Closing log transport
>         fd; fd='9'
>
>
>         In order to get more information, I set the following flags in
>         init.d: "-v -d -t".
>
>         This did not give me any more information about the TCP
>         disconnect, however I did notice that a lot of my normal
>         messages were preceeded by the following text:
>
>         <47>1 2010-01-05T10:29:32.323-06:00 server-db-01 syslog-ng
>         29213 - [meta sequenceId="2733718"] debug Incoming log entry;
>         line=
>
>         A normal log message then follows the '=' sign.
>
>         A decent percentage of my messages are preceeded by this
>         throughout the day, but just before the disconnect it appears
>         that all of my messages from server-db-01 are preceeded by the
>         debug line.  Any ideas as to what could be going on?  I have
>         included my config file below if that helps.
>
>         Any assistance would be greatly appreciated.
>         -Jim
>
>         @version: 3.0
>         #Default configuration file for syslog-ng.
>         #
>         # For a description of syslog-ng configuration file
>         directives, please read
>         # the syslog-ng Administrator's guide at:
>         #
>         #
>         http://www.balabit.com/dl/html/syslog-ng-admin-guide_en.html/bk01-toc.html
>         #
>         options {
>         keep_hostname(yes);
>         keep_timestamp(yes);
>         frac_digits(3);
>         };
>         source all {
>         internal();
>         syslog(ip("192.168.27.198") port(20514) transport("tcp")
>         log_fetch_limit(100));
>         };
>         destination allclientsfile {
>         file("/data/local/Logs/server-$YEAR-$MONTH-$DAY.log"
>         flags(syslog-protocol)
>         flush_timeout(100)
>         create_dirs(yes)
>         dir_owner(jpirman)
>         dir_group(jpirman)
>         owner(jpirman)
>         group(jpirman)
>         template("$PRIORITY $MESSAGE")
>         );
>         };
>         destination msgserver {
>         udp("127.0.0.1" port(20515)
>         flush_timeout(100)
>         template("$ISODATE $PROGRAM $PRIORITY $MESSAGE\n"));
>         };
>         log { source(all); destination(allclientsfile);
>         destination(msgserver);};
>
>
>
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>
>            
>
>
>
>     -- 
>     pzolee
>        
>
>
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>        
>
>
>
> -- 
> pzolee
>
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>    


-- 
pzolee
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