[openbox] openbox connected to remote display doesn't know X server gone

Anthony Thyssen A.Thyssen at griffith.edu.au
Sun Sep 27 21:19:48 EDT 2009


On Fri, 25 Sep 2009 08:51:52 -0500
Xavier Toth <txtoth at gmail.com> wrote:

| On Thu, Sep 24, 2009 at 9:47 AM, txtoth <txtoth at gmail.com> wrote:
| > On Thu, Sep 24, 2009 at 1:57 AM, Anthony Thyssen
| > <A.Thyssen at griffith.edu.au> wrote:
| >> On Wed, 23 Sep 2009 16:13:10 -0500
| >> Xavier Toth <txtoth at gmail.com> wrote:
| >>
| >> | I'm running an X server for remote display purposes (some might call
| >> | it an X terminal). The X client starts an openbox session when a user
| >> | logs in. If I power off the X server box (something that shouldn't
| >> | happen but can) when a user is logged in and then do a ps on the X
| >> | client I see that openbox and a number of other processes started by
| >> | the openbox session continue to run indefinitely. It appears that
| >> | openbox doesn't know that it's X connection has been lost. Is there
| >> | anything that can be done to cleanup these dead sessions?
| >> |
| >> Many internet connections don't die when the remote server dies.
| >> Basically it cant't tell if the host has disappeared, or is just
| >> not talking.
| >>
| >> When the host comes back online usally such connections get a error
| >> about no such connection from the rebooted host, and the clients
| >> die.  But only when the host comes back.
| >>
| >> This is especially the case with X window UDP packets.
| >>
| >> The other solution is that the socket connection be setup with a
| >> 'keepalive' flag.  This checks the connection for response, and
| >> closed dead connections when the remote client 'dissapears'.
| >>
| >> X windows via SSH tunneling encryption is the standard way X window
| >> connections are handled these days.   And SSH has options to use
| >> 'keepalive' socket techniques.
| >>
| >> In the system ssh_config or your personal $HOME/.ssh/config
| >> add the following...
| >>
| >> ----------8<--------------
| >> Host *
| >>  TCPKeepAlive yes
| >>  ServerAliveInterval 1800
| >> ----------8<--------------
| >>
| >> the second item is not really needed, but sends an "I'm here"
| >> type packet every 5 mins to prevent some firewalls and routers
| >> from killing 'unused connections'.  that takes care of the opposite
| >> problems.   connections dying when you aren't using them even though
| >> nothing is wrong at either end.
| >>
| >> Both flags are worth it.
| >>
| >> PS: to ensure X windows is passed with SSH by default also include a
| >>   ForwardX11 yes
| >> in the above.
| >>
| >>
| >>  Anthony Thyssen ( System Programmer )    <A.Thyssen at griffith.edu.au>
| >>  -----------------------------------------------------------------------------
| >>            Graffito in a MIT lavatory...
| >>                   Heisenberg might have been here
| >>  -----------------------------------------------------------------------------
| >>     Anthony's Home is his Castle     http://www.cit.gu.edu.au/~anthony/
| >> _______________________________________________
| >> openbox mailing list
| >> openbox at icculus.org
| >> http://icculus.org/mailman/listinfo/openbox
| >>
| >
| > We are using an ipsec.The X library is supposedly setting SO_KEEPALIVE
| > on connections it creates so I'll try setting
| > /proc/sys/net/ipv4/tcp_keepalive_time and see if that helps. Thanks
| >
| > Ted
| >
| 
| I set the time in  /proc/sys/net/ipv4/tcp_keepalive_time to 1800 but
| still openbox never realizes that the X server it was connected to is
| no longer running. This causes a real problem because besides openbox
| there are a number of its children and eventually you can have a box
| running with a number of zombies, not good in a production
| environment.
| 
have you tried the connections via SSH?



  Anthony Thyssen ( System Programmer )    <A.Thyssen at griffith.edu.au>
 -----------------------------------------------------------------------------
    Two hydrogen atoms walk into a bar.
    One says, "I've lost my electron".
    The other says, "Are you sure?"
    The first replies, "Yes, I'm positive..."
 -----------------------------------------------------------------------------
     Anthony's Home is his Castle     http://www.cit.gu.edu.au/~anthony/


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