Date: Sat, 22 Mar 2014 00:18:20 -0700 From: Kevin Oberman <rkoberman@gmail.com> To: Marcelo Gondim <gondim@bsdinfo.com.br> Cc: FreeBSD Stable Mailing List <freebsd-stable@freebsd.org> Subject: Re: sshd with zombie process on FreeBSD 10.0-STABLE - workaround Message-ID: <CAN6yY1uEADbTHyrP7=uEgEUQWR%2BcTW2grq=aK00i9idW=ver%2Bg@mail.gmail.com> In-Reply-To: <532D2852.1010700@bsdinfo.com.br> References: <53016D97.5030909@bsdinfo.com.br> <CAN6yY1uucfkdXxkCF30w1Q9vffRpDLxM90Sz1XVbdn5W69vQMg@mail.gmail.com> <5329D81E.7040709@bsdinfo.com.br> <201403201058.38555.jhb@freebsd.org> <532B7DEC.7010809@bsdinfo.com.br> <CAN6yY1sf0z_jBJgBy2dZX0a3JJnyTnq76_DepXzG32GWgHHO6A@mail.gmail.com> <532D2852.1010700@bsdinfo.com.br>
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On Fri, Mar 21, 2014 at 11:06 PM, Marcelo Gondim <gondim@bsdinfo.com.br>wrote: > Em 22/03/14 02:02, Kevin Oberman escreveu: > >> On Thu, Mar 20, 2014 at 4:46 PM, Marcelo Gondim <gondim@bsdinfo.com.br >> >wrote: >> >> Em 20/03/14 11:58, John Baldwin escreveu: >>> >>> On Wednesday, March 19, 2014 1:47:10 pm Marcelo Gondim wrote: >>>> >>>> Em 19/03/14 13:01, Kevin Oberman escreveu: >>>> >>>>> On Wed, Mar 19, 2014 at 6:00 AM, Marcelo Gondim >>>>>> >>>>>> <gondim@bsdinfo.com.br>wrote: >>>>> Hi all, >>>>> >>>>>> While the solution does not appear, did the script below and put it in >>>>>>> crontab to automatically delete zombie sshd processes. >>>>>>> >>>>>>> the_walking_dead.sh: >>>>>>> >>>>>>> #!/bin/sh >>>>>>> kill -9 `ps afx|grep sshd|grep unknown|awk '{print $1}'` >>>>>>> >>>>>>> >>>>>>> Put this in /etc/crontab: >>>>>>> >>>>>>> 00 1 * * * root the_walking_dead.sh >>>>>>> >>>>>>> >>>>>>> If 'kill -9' works, the process is not really a zombie. It simply >>>>>>> >>>>>> still >>>>>> >>>>>> has >>>>> a socket open and is waiting for it to be closed before exiting. >>>>> >>>>>> You might takes a look at network sockets with sockstat(1) and see if >>>>>> you >>>>>> can get any indication of why these sockets are not being closed. It >>>>>> may >>>>>> >>>>>> be >>>>> that the issue is not sshd but some other issue in the OS leaving >>>>> sockets >>>>> >>>>>> open. >>>>>> >>>>>> Hi Kevin, >>>>>> >>>>> My ps -afx below: >>>>> >>>>> [...] >>>>> 42139 - Is 0:00.01 sshd: unknown [priv] (sshd) >>>>> 42140 - Z 0:00.01 <defunct> >>>>> 42141 - IW 0:00.00 sshd: unknown [pam] (sshd) >>>>> 58445 - Is 0:00.01 sshd: unknown [priv] (sshd) >>>>> 58446 - Z 0:00.02 <defunct> >>>>> 58447 - IW 0:00.00 sshd: unknown [pam] (sshd) >>>>> 65635 - Is 0:00.01 sshd: vinicius [priv] (sshd) >>>>> 65636 - Z 0:00.01 <defunct> >>>>> [...] >>>>> >>>>> # sockstat | grep 42140 >>>>> # >>>>> >>>>> # sockstat | grep 58446 >>>>> # >>>>> >>>>> # sockstat | grep 65636 >>>>> # >>>>> >>>>> No associated socket with zombie process. >>>>> >>>>> Do a pstree. I bet the zombies are children of the other processes >>>> that >>>> are stuck on a socket as Kevin described. >>>> >>>> # ps afx|grep sshd |grep unk >>>> >>> 10948 - Is 0:00.02 sshd: unknown [priv] (sshd) >>> 10955 - IW 0:00.00 sshd: unknown [pam] (sshd) <==== >>> 11701 - Is 0:00.02 sshd: unknown [priv] (sshd) >>> 11704 - IW 0:00.00 sshd: unknown [pam] (sshd) >>> 25450 - Is 0:00.01 sshd: unknown [priv] (sshd) >>> 25452 - IW 0:00.00 sshd: unknown [pam] (sshd) >>> 41193 - Is 0:00.02 sshd: unknown [priv] (sshd) >>> 41196 - IW 0:00.00 sshd: unknown [pam] (sshd) >>> 42193 - Is 0:00.02 sshd: unknown [priv] (sshd) >>> 42195 - IW 0:00.00 sshd: unknown [pam] (sshd) >>> 80638 - Is 0:00.02 sshd: unknown [priv] (sshd) >>> 80640 - IW 0:00.00 sshd: unknown [pam] (sshd) >>> 81484 - Is 0:00.02 sshd: unknown [priv] (sshd) >>> 81486 - IW 0:00.00 sshd: unknown [pam] (sshd) >>> >>> With proctstat I could see the socket as follows: >>> >>> # procstat -f 10955 >>> PID COMM FD T V FLAGS REF OFFSET PRO NAME >>> 10955 sshd text v r r------- - - - /usr/sbin/sshd >>> 10955 sshd cwd v d r------- - - - / >>> 10955 sshd root v d r------- - - - / >>> 10955 sshd 0 v c rw------ 6 0 - /dev/null >>> 10955 sshd 1 v c rw------ 6 0 - /dev/null >>> 10955 sshd 2 v c rw------ 6 0 - /dev/null >>> 10955 sshd 3 s - rw---n-- 2 0 TCP 186.xxx.xx.2:22 >>> 186.xxx.xx.8:57035 >>> 10955 sshd 5 p - rw------ 2 0 - - >>> 10955 sshd 6 s - rw------ 2 0 UDS - >>> 10955 sshd 7 p - rw------ 1 0 - - >>> 10955 sshd 8 s - rw------ 2 0 UDS - >>> >>> I do not understand why these connections are remaining locked in FreeBSD >>> 10.0 >>> >>> I'll try this sysctl: net.inet.tcp.delayed_ack=0 >>> >>> If the problem is still showing up, can you see what is going on with >> the >> socket? What is the state of the connection. Try "netstat -f inet -p tcp" >> and see what state the connection is in. I'm wondering if there is some >> sort of race going on where the socket hangs. >> >> Ideally I'd look to try and capture the packets st the end of the session. >> Can you do something to trigger this reliably? if so "standard" "tcpdump >> -pw file.bpf host HOST". I seem to recall that these connections are >> scheduled. If so, you can put the packet capture in a crontab to run at >> the >> same time. If you feed this to a tool like wireshark, you should get a >> good >> idea of what is happening, if not why. I understand that the timing of >> this >> might be very tricky. >> > Hi Kevin, > > Thanks for your help. > > I did the netstat and the state of the connection is closed as you can see > below: > > # procstat -f 26177 > PID COMM FD T V FLAGS REF OFFSET PRO NAME > 26177 sshd text v r r------- - - - /usr/sbin/sshd > 26177 sshd cwd v d r------- - - - / > 26177 sshd root v d r------- - - - / > 26177 sshd 0 v c rw------ 6 0 - /dev/null > 26177 sshd 1 v c rw------ 6 0 - /dev/null > 26177 sshd 2 v c rw------ 6 0 - /dev/null > 26177 sshd 3 s - rw---n-- 2 0 TCP > 186.193.48.10:4321 186.193.48.8:50094 > 26177 sshd 4 s - rw------ 1 0 UDS - > 26177 sshd 5 p - rw------ 2 0 - - > 26177 sshd 6 s - rw------ 2 0 UDS - > > # procstat -f 10110 > PID COMM FD T V FLAGS REF OFFSET PRO NAME > 10110 sshd text v r r------- - - - /usr/sbin/sshd > 10110 sshd cwd v d r------- - - - / > 10110 sshd root v d r------- - - - / > 10110 sshd 0 v c rw------ 6 0 - /dev/null > 10110 sshd 1 v c rw------ 6 0 - /dev/null > 10110 sshd 2 v c rw------ 6 0 - /dev/null > 10110 sshd 3 s - rw---n-- 2 0 TCP > 186.193.48.10:4321 186.193.48.8:63048 > 10110 sshd 4 s - rw------ 1 0 UDS - > 10110 sshd 5 p - rw------ 2 0 - - > 10110 sshd 6 s - rw------ 2 0 UDS - > > # netstat -f inet -p tcp > Active Internet connections > Proto Recv-Q Send-Q Local Address Foreign Address (state) > tcp4 0 0 bart.24173 pppoe17250.8728 ESTABLISHED > tcp4 0 0 bart.53795 pppoe17249.8728 TIME_WAIT > tcp4 0 0 bart.54191 pppoe149.8728 TIME_WAIT > tcp4 0 0 bart.12476 pppoe148.8728 TIME_WAIT > tcp4 0 0 bart.36846 pppoe142.8728 TIME_WAIT > tcp4 0 0 bart.39944 186.193.48.22.8728 TIME_WAIT > tcp4 0 0 bart.60233 186.193.48.25.8728 TIME_WAIT > tcp4 0 0 bart.50946 186.193.48.9.8728 TIME_WAIT > tcp4 0 0 bart.13403 186.193.48.19.8728 TIME_WAIT > tcp4 0 0 bart.36982 zeus.linuxinfo.c.8728 TIME_WAIT > tcp4 0 0 bart.rwhois pppoe769.49896 ESTABLISHED > tcp4 0 0 bart.mysql mail.15711 ESTABLISHED > tcp4 0 0 bart.mysql mail.16087 ESTABLISHED > tcp4 0 0 bart.mysql mail.25051 ESTABLISHED > tcp4 0 0 bart.mysql mail.59126 ESTABLISHED > tcp4 0 0 bart.mysql mail.59051 ESTABLISHED > tcp4 0 0 bart.mysql mail.29446 ESTABLISHED > tcp4 0 0 bart.mysql mail.45453 ESTABLISHED > tcp4 0 0 bart.mysql mail.14938 ESTABLISHED > tcp4 0 0 bart.mysql mail.46230 FIN_WAIT_2 > tcp4 0 0 bart.mysql mail.16930 FIN_WAIT_2 > tcp4 0 0 bart.mysql mail.28074 FIN_WAIT_2 > tcp4 0 0 bart.mysql mail.53686 FIN_WAIT_2 > tcp4 0 0 bart.mysql mail.14448 FIN_WAIT_2 > tcp4 0 0 bart.mysql mail.52487 ESTABLISHED > tcp4 0 0 bart.rwhois 186.193.48.8.50094 CLOSED > <==== > tcp4 0 0 bart.mysql mail.38286 FIN_WAIT_2 > tcp4 0 0 bart.mysql mail.32387 FIN_WAIT_2 > tcp4 0 0 bart.mysql mail.52219 ESTABLISHED > tcp4 0 0 bart.mysql mail.52144 ESTABLISHED > tcp4 0 0 bart.mysql mail.18862 FIN_WAIT_2 > tcp4 0 0 bart.mysql mail.52636 FIN_WAIT_2 > tcp4 0 0 bart.mysql mail.51607 FIN_WAIT_2 > tcp4 0 0 bart.mysql mail.62581 FIN_WAIT_2 > tcp4 0 0 bart.mysql mail.23071 ESTABLISHED > tcp4 0 0 bart.mysql mail.22862 FIN_WAIT_2 > tcp4 0 0 bart.rwhois 186.193.48.8.63048 CLOSED > <==== > tcp4 0 0 bart.mysql mail.42479 FIN_WAIT_2 > tcp4 0 0 bart.mysql mail.18146 ESTABLISHED > tcp4 0 0 bart.mysql mail.46731 FIN_WAIT_2 > tcp4 0 0 bart.mysql mail.20498 ESTABLISHED > tcp4 0 0 bart.62869 186.193.48.2.1190 ESTABLISHED > tcp4 0 0 bart.mysql mail.55353 ESTABLISHED > I'm sorry. I am now even more confused. Maybe I need to re-read the entire thread. I thought that the hung processes were sshd. These are rwhois. Or is there an ssh tunnel carrying the rwhois connections? (I see no sshd connections in this list.) -- R. Kevin Oberman, Network Engineer, Retired E-mail: rkoberman@gmail.com
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