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Re: ssh ServerAlive probes


i was faced same problem while designing client server based system.
In that after connecting to host_B to host_A, if any host disconnected
it was not notifing to another even if notifing method defined well.

How to do that?

On 4/5/11, Don Tucker <dtucker@xxxxxxxxxxxxxxxx> wrote:
> Hello,
> I am working on an application that needs to be able to rapidly detect a
> lost connection between an ssh client and ssh server.  I am using ssh to
> do local and remote port forwarding, and sending data across the
> forwarded ports.  I was originally relying upon the TCPKeepAlive probes,
> but found that I could not consistently detect a lost detection.  Using
> the ServerAliveInterval and ServerAliveCountMax options, however, I am
> able to consistently detect a lost connection.  The problem is, if I am
> using a low-bandwidth connection (cellular modem), and I am pushing a
> significant amount of data across, it seems that this hinders the
> communication between the client and server with the ServerAlive
> messages.  In other words, when I am actually USING the connection, my
> application can mistakenly detect the connection as lost because the
> ServerAliveInterval x ServerAliveCountMax is exceeded without a response
> from the server.  I was surprised at this behavior, since I expected the
> ServerAlive probes to only start after data flow between the client and
> server machines across that connection had ceased, but perhaps I am
> misunderstanding.  I do not have much leeway as to how the server is
> configured.  Can someone recommend a way to be able to both (1) quickly
> detect a lost connection [which, seems to require the interval and
> countmax be small], but not mistakenly detect the connection as lost
> when it is being used?
> Thank you for any assistance.
> Don

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