Telnet (and tcp applications in general) sends a keepalive pack every 75 seconds, if you had been lucky enough to resync without clashing with one of these 75 second intervals, your link would have continued.
more specifically, i think the message your telnet client sends to the server is "ack 31" and it expects in reply "ack 4". if the server doesn't receive an ack 31 within it's window, it will end the connection, and the client will end the link without an ack 4 in response.
if you're using a UDP application instead of TCP, it'll implement its own similar keepalive system independantly of any other applications.
if you regularly have these problems, you can look into a gpl application called screen - you use it as part of your login session setup and it will let you run multiple telnet sessions over one link, and more usefully for you, reconnect to a session which had been lost
Ewan
On 5/24/06, Ted Harding Ted.Harding@nessie.mcc.ac.uk wrote:
Hi Folks,
Someone out there will know the answer to my ignorant query ...
Suppose I have an up-and-running internet connection via my ISP. So I telnet into a remote host (e.g. nessie.mcc.ac.uk) and establish a login-session. So far so good.
Next, for DSL reasons, the internet connection is interrupted (the router re-syncs). Shortly afterwards, it is re-established again.
But now, I have lost contact with the login session.
My question is: What is the mechanism (or perhaps absence of mechanism) leading to losing the contact?
Or, turning the question on its head, what is it that keeps my link with the remote host alive so long as the internet connection stays up?
The naive version of the question: If my packets can find their way to my login to nessie before the line drops, and nessie's can find their way back to my telnet, how come they can't continue to do so after the line drops and is re-estiblished?
I hope people understand what I'm asking -- I'll try better if you don't!
Thanks, and best wishes to all, Ted.
E-Mail: (Ted Harding) Ted.Harding@nessie.mcc.ac.uk Fax-to-email: +44 (0)870 094 0861 Date: 24-May-06 Time: 21:03:41 ------------------------------ XFMail ------------------------------