I just installed Ubuntu yesterday; when i ssh to github, rather than being prompted for a password, it just stalls. The command i entered was:
ssh -T firstname.lastname@example.org
After entering, the cursor blinks but nothing comes up. I've tried using the key on my friend's laptop; he gets a permission denied error message, meaning there is different behavior on different machines. I have a github account with my ssh key included. I was actually able to get my account to work freely on a separate machine, but alas i've had no luck on my personal computer. For reference, I'm running a Lenovo Ideapad 530s.
UPDATE: I was able to ssh to github on a different terminal, which is running scientific linux. Thus i am inclined to believe that the problem is related directly to my machine. As i mentioned, i just installed Ubuntu and thus am unsure how my device might be configured improperly.