Server Unexpectedly Closed Network Connection
Dec 29, 2016 - Please keep in mind that the keys generated by PuTTY are not compatible with the OpenSSH server (unless you export them to be compatible.
when she tries to log on
this shows up 'Server unexpectedly closed network connection.' like a kind of alert.
I host the site and no one else is having trouble but here and were about 10 that log on with the same port username and password.
The port and host name and everything is all correct.
So I don't see why this continues to happen even after she's restarted her computer and has never had this problem before.
If you could possibly redirect me to where I can find Help or even answer my question here It would be greatly appreciated.
Thank you.
I have a strange issue with a server (hosted in AWS). I can ping from the laptop of my office and it seems that I can also connect on port 22 with telnet like this:
output of telnet:
But If i try to connect with Putty I recieve the following message as soon as I try to click Open:
server unexpectedly closed network connection
Note: that other collegues located in other sites can connect to it.
Note2: I can ping to it
Note3: I need to connect from windows
PuttyLog:
Server Unexpectedly Closed Network Connection Git
2 Answers
Your client and server disagree on something about the key exchange process. Possibly the server has been excessively 'hardened' and either requires stronger DH groups than the old PuTTY version can offer.
To know the exact details you'd have to enable debug logging on the server side, i.e on the end which cuts the connection first.
Either way, PuTTY 0.62 was released in 2011 – nearly six years ago. Since then it has received many updates (the latest version is 0.70), and recent versions are more likely to be accepted by your server.
More importantly, PuTTY 0.68 and later support ECDH, i.e. elliptic-curve key exchange, using both P-256 and X25519. This feature replaces traditional DH altogether, is somewhat faster and more secure, and in particular X25519 is likely to be included in even the strictest copy&pasted configurations.
So as @grawity posted in the comments, I had an out-dated version of Putty.I have updated it to 0.70 and now it works.
So if you can ping your machine and telnet connects to port 22 while putty fails, the answer is to update your putty.
grawity