Managing SSH keys!!!

It was all sudden. I managed to configure the ssh key and it shows you are not authorised to make any changes!!?? 

So what it is? Why this happens??

While trying to figure it out I understood that the ssh agent is confused with the identity file. You can see the permission is denied from the public key. The problem is caused after I added my Gitlab ssh key. Assuming the ssh-agent is confused with my Gitlab and Github ssh keys. When I try to push something, ssh checks for my identity file and  it doesn't know which file to pick!! So it might picked  Github ssh key for Gitlab server which caused the error.

Solution

The problem was identifying the identity file. So I made a config file in .ssh folder for a better understanding.

vi ~/.ssh/config

Host gitlab.com
	PreferredAuthentications publickey
	IdentityFile ~/.ssh/gitlab_key_location
Host github.com
	PreferredAuthentications publickey
	IdentityFile ~/.ssh/github_key_location

Now the ssh agent knows where to look for the private key for each hosts.