I am under a proxy and I am pushing in to git successfully for quite a while.
Now I am not able to push into git all of a sudden.
I have set the RSA key and the proxy and double checked them, with no avail and git is throwing me the error shown in the title of the page.
The reason could be the firewall modification since you are on a network, in which case they may deliberately block some ports.
To double check if this is the reason, run:
ssh -T git@github.com
This should timeout. If that's the case, then use the http protocol instead of ssh. Change your url in the config file to http:
git config --local -e
and change:
url = git@github.com:username/repo.git
to
url = https://github.com/username/repo.git