I've seen the question here but I'm not sure if the same solution would apply to me
I'm on Emacs 25.1 / Ubuntu 16.04. I've just set up SSH-keys according to https://help.github.com/articles/adding-a-new-ssh-key-to-your-github-account/ and I've added the public key to my GitHub account.
When I try to push though, Magit prompts me for my password to my account firstname.lastname@example.org (as always) rather than seeing that I've set an SSH-key into ssh-agent.
M-x getenv SSH_AGENT_PID doesn't exist and
M-x getenv SSH_AUTH_SOCK is
echo $SSH_AGENT_PID is 18145. What is the next step from here?