Bug#856843: [Pkg-samba-maint] Bug#856843: smbclient: connection flood to port 445 on mounting cifs volume under kernel 4.9.0
Then this is a kernel issue, I assumed that cifsd was part of smbclient
and I see that taking up resources, but maybe that is unrelated (it was
in a normal resource usage range).
Please reassign as you think appropriate.
On 2017-03-05 14:36, Jelmer Vernooij wrote:
> On Sun, Mar 05, 2017 at 12:30:33PM +0100, nils wrote:
>> Package: smbclient
>> Version: 2:4.2.14+dfsg-0+deb8u2
>> Severity: important
>>
>> Hello,
>> after upgrading my kernel from 4.0.8 to 4.0.9 I am getting connection floods to
>> my FreeNAS samba server from my debian machine. I never had this issue with
>> 4.0.8
>>
>> Linux dnet64 4.9.0-0.bpo.1-amd64 #1 SMP Debian 4.9.2-2~bpo8+1 (2017-01-26)
>> x86_64 GNU/Linux
>> ii smbclient 2:4.2.14+dfsg-0+deb8u2 amd64 command-line
>> SMB/CIFS clients for Unix
>>
>> After mouting the cifs share(s) everything is OK for about 10 minutes, then a
>> flood of connections happens. Here is an extract of 'netstat -an' run every
>> second. Only one or two connections are shown for every 'netstat -an' run. The
>> connections are opening and closing at an incredible speed (nethogs goes to
>> 100% and doesn't show anything because it's overwhelmed). gkrellm reports about
>> 70k/Sec traffic due to this. See how the source port numbers increase
>> increadibly quickly to get an idea of how many connections are really
>> happening...
>> ....
>> tcp 0 1 10.0.2.15:55044 192.168.2.88:445 SYN_SENT
>> tcp 0 1 10.0.2.15:55252 192.168.2.88:445 SYN_SENT
>> tcp 0 0 10.0.2.15:55288 192.168.2.88:445 ESTABLISHED
>> tcp 0 1 10.0.2.15:55314 192.168.2.88:445 SYN_SENT
>> tcp 0 1 10.0.2.15:55348 192.168.2.88:445 SYN_SENT
>> tcp 0 0 10.0.2.15:55396 192.168.2.88:445 ESTABLISHED
>> tcp 0 1 10.0.2.15:55454 192.168.2.88:445 SYN_SENT
>> tcp 0 0 10.0.2.15:55500 192.168.2.88:445 ESTABLISHED
>> tcp 0 0 10.0.2.15:55544 192.168.2.88:445 ESTABLISHED
>> tcp 0 42 10.0.2.15:55586 192.168.2.88:445 ESTABLISHED
>> tcp 0 0 10.0.2.15:55630 192.168.2.88:445 ESTABLISHED
>> tcp 0 0 10.0.2.15:55676 192.168.2.88:445 ESTABLISHED
>> tcp 0 0 10.0.2.15:55720 192.168.2.88:445 ESTABLISHED
>> tcp 0 1 10.0.2.15:55770 192.168.2.88:445 SYN_SENT
>> tcp 1 0 10.0.2.15:55820 192.168.2.88:445 CLOSE_WAIT
>> tcp 0 1 10.0.2.15:55868 192.168.2.88:445 SYN_SENT
>> tcp 0 0 10.0.2.15:55912 192.168.2.88:445 ESTABLISHED
>> tcp 0 0 10.0.2.15:55962 192.168.2.88:445 ESTABLISHED
>> tcp 1 0 10.0.2.15:56010 192.168.2.88:445 CLOSE_WAIT
>> tcp 0 1 10.0.2.15:56058 192.168.2.88:445 SYN_SENT
>> tcp 0 0 10.0.2.15:56056 192.168.2.88:445 LAST_ACK
>> tcp 0 0 10.0.2.15:56104 192.168.2.88:445 ESTABLISHED
>> tcp 0 0 10.0.2.15:56162 192.168.2.88:445 ESTABLISHED
>> tcp 0 0 10.0.2.15:56202 192.168.2.88:445 ESTABLISHED
>> tcp 0 1 10.0.2.15:56246 192.168.2.88:445 SYN_SENT
>> tcp 0 0 10.0.2.15:56290 192.168.2.88:445 ESTABLISHED
>> ....etc.
>>
>> Rebooting in 4.0.8 makes the issue go away, and I can have the shares mounted
>> as long as I want without a connection flood. Hence I assume that it's a
>> smbclient + Kernel 4.0.9 issue
> smbclient is a command-line tool, if you're just mounting CIFS shares then this
> is an issue in the kernel rather than in smbclient.
>
> Jelmer
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