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Old 12-30-2013, 05:01 AM   #1
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Registered: Dec 2013
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"Server unexpectedly closed network connection"-PuTTY

Hi there,

I'm trying to connect to a Uni server through PuTTY but getting the following error.

server unexpectedly closed network connection

I didn't face this error so far, and I've been using PuTTY to connect to that server for the past couple of months. And now I'm suddenly seeing this error. I'm using my home network connection for this and when I try to connect through a different network it works fine.I tried everything I could, restarting the router or clearing the PuTTY's cache, but still no luck.

I know it's probably something to do with my network, but not sure what it is. If you can give me any suggestions on how to go about solving this problem it'll be brilliant. I'm very new to all this and it would be appreciated if you can help me out with this.

Many thanks!

Last edited by hannahb29; 12-30-2013 at 05:05 AM.
Old 12-30-2013, 05:39 AM   #2
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HI hannahb,

Welcome to LQ.

Are you able to ping the IP ?

If you can ping you were using ssh/telnet ? Check the corresponding port is opened .
Old 12-30-2013, 08:18 AM   #3
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Check if you a firewall on your local machine blocking the requests to the host.
Old 12-30-2013, 08:25 AM   #4
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He appears able to ping, and there doesn't seem to be a firewall issue (he gets connected, but unexpectedly disconnected, which MIGHT be a firewall issue though unlikely).

How long after you get connected to the server does it disconnect?

One possiblity (since it used to work) is that the server may have enabled a mandatory "keep alive" packet every so often. I believe putty has an option to enable this. What it does is send an empty packet every so often during idle time, so that the server knows the client is still connected. This allows the server to terminate broken TCP connections (timeout around 15 minutes) much earlier, and reclaim resources sooner.


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