Segment failed SYNCOOKIE?

Andre Oppermann andre at freebsd.org
Wed May 30 12:39:59 UTC 2007


Steve Kargl wrote:
> On Mon, May 28, 2007 at 05:31:18PM +0200, Andre Oppermann wrote:
>> Steve Kargl wrote:
>>> Anyone have ideas on how to cure
>>>
>>> May 25 16:20:03 node13 kernel: TCP: [192.168.0.15]:53815 to
>>> [192.168.0.13]:50992 tcpflags 0x11<FIN,ACK>; syncache_expand:
>>> Segment failed SYNCOOKIE authentication
>>>
>>> The hardware and kernel on 192.168.0.15 and 192.168.0.13
>>> are identical.
>> Do you have any daemon listening on [192.168.0.13]:50992?
>>
> 
> I've set "net.inet.tcp.syncookies=0" in /boot/loader.conf
> to disable syncookies.  I'm now seeing 
> 
>> May 28 16:39:59 node13 kernel: bge0: watchdog timeout -- resetting
>> May 28 16:39:59 node13 kernel: bge0: link state changed to DOWN
>> May 28 16:40:02 node13 kernel: bge0: link state changed to UP
>> May 28 16:41:51 node13 kernel: TCP: [192.168.0.13]:62460 to
>> [192.168.0.13]:56460 tcpflags 0x10<ACK>; syncache_expand: Spurious ACK
>> May 28 16:41:51 node13 kernel: TCP: [192.168.0.13]:64274 to
>> [192.168.0.13]:49985 tcpflags 0x10<ACK>; syncache_expand: Spurious ACK
>> May 28 16:41:51 node13 kernel: TCP: [192.168.0.11]:51473 to
>> [192.168.0.13]:57885 tcpflags 0x11<FIN,ACK>; syncache_expand: Spurious ACK
>> May 28 16:41:51 node13 kernel: TCP: [192.168.0.12]:49393 to
>> [192.168.0.13]:57885 tcpflags 0x10<ACK>; syncache_expand: Spurious ACK
>> May 28 16:41:51 node13 kernel: TCP: [192.168.0.12]:61494 to
>> [192.168.0.13]:52887 tcpflags 0x10<ACK>; syncache_expand: Spurious ACK
>> May 28 16:41:51 node13 kernel: TCP: [192.168.0.12]:63379 to
>> [192.168.0.13]:63472 tcpflags 0x10<ACK>; syncache_expand: Spurious ACK
> 
> This is occurring with an openmpi application.

I have committed further changes and logging to tcp_input() that
will give more insight into this.  Please update to the latest
current and report the new log messages.

-- 
Andre


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