While trying to logging into a Linux machine you may get the error:
ssh_exchange_identification: Connection closed by remote host
At the same time, you may be able to login to this server from some other machine.
The most common reason for this error is, the machine from where you are trying to login is not allowed to access the server. Means, your local machine is not listed in /etc/host.allow file of the server.
So, please check the following files on the server (you will have to login to the server from a machine which is allowed to access the server. Or else you should contact someone who can do it for you ;))
If you are not sure what should be listed in the /etc/hosts.allow, add the following line to it (and comment all other lines, if it’s not already)
This entry will allow SSH access from anywhere.
By default, there won’t be any entry in /etc/hosts.deny file