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Date:      Mon, 17 Jun 2002 19:23:26 -0700
From:      "Philip J. Koenig" <pjklist@ekahuna.com>
To:        questions@FreeBSD.ORG
Cc:        Dan Nelson <dnelson@allantgroup.com>
Subject:   Re: kicking users
Message-ID:  <20020618022326603.AAA594@empty1.ekahuna.com@pc02.ekahuna.com>
In-Reply-To: <20020618013853.GB6214@dan.emsphone.com>
References:  <20020618013550.GA6214@dan.emsphone.com>

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On 17 Jun 2002, at 20:38, Dan Nelson boldly uttered: 

> In the last episode (Jun 17), Dan Nelson said:
> > In the last episode (Jun 17), Philip J. Koenig said:
> > > I've had trouble killing logins manually that way, although I admit 
> > > that I've been using a plain 'kill' command, not 'kill -9'.  
> > > 
> > > Where I need to do this most often is for SSH users whose sessions 
> > > time out due to connectivity problems.  I kill their processes and 
> > > shell, but the login still just sits there for a really long time 
> > > (hours? days? .. in 'who' anyway) before it goes away.
> > 
> > If you kill -9 sshd, it doesn't get a chance to clean up the login
> > records.  Try just kill -9'ing the user's shell.



I dont' kill sshd, just the shell and any other user-owned processes.

 
> > You can also force the connections to time out all by themselves by
> > setting net.inet.tcp.always_keepalive=1 in /etc/sysctl.conf.  That'll
> > force the kernel to send an empty packet after a TCP socket has been
> > idle for a couple of hours.  If the packet isn't acked, the kernel
> > closes the socket.
> 
> Hmm.  According to the sshd manpage, it already enables keepalives. 
> Ignore my sysctl idea, then.


Interesting you should mention that though.  I have a problem where 
sessions get killed off, and I think it's because of the stateful 
firewall on one or both ends of the connection timing out the session 
when no packets traverse it for 5-10 mins. (this is actually the main 
reason I end up wanting to kill 'zombie' user sessions)

Even with the keepalive feature turned on, the problem remains.  Out 
of 3 ssh clients I've tried, the only one so far that has a working 
keepalive function that fixes this problem is Putty. (for Windows)  
Both the Windows client from SSH Corp and the openssh client shipped 
with FreeBSD 4.3-4.6 won't keep the connection up. (I don't remember 
if I tried a Linux installation of openssh)


Phil


--
Philip J. Koenig                                       pjklist@ekahuna.com
Electric Kahuna Systems -- Computers & Communications for the New Millenium


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