not connecting to ssh host

i have tried to connect to the host for my school to turn in my assignments but its not doing so, the all the programs i tried to connect to the host with always tell me the same thing
connection closed by remote host
what does this mean and what can i do to get it to stop doing this and make it connect to the host so i can turn in my work

i have used the ssh command in linux distros, putty on both linux and windows, ans the ssh file transfer client in windows and all of them told me the same story, whats going on here