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

txtoth txtoth at gmail.com
Thu Sep 24 10:47:56 EDT 2009


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/
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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


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