Using git with SSH

2019-06-15
best practices AWS



Secure Shell (SSH) is a cryptographic network protocol for operating network services securely over an unsecured network. This allows you to connect securely to other services or machines.

In this post I am going to explain how to configure your linux machine to github using SSH.

1. Create SSH keys

First we will create a SSH key that will allow you to connect to github.

ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

Then I suggest you save the SSH key with some usefull name like /home/ubuntu/.ssh/github_ssh

Finally add a passphrase. This will ensure that your SSH credentials are safe even if someone access your computer.

2. Use keychain

The SSH key you just created has a passphrase and you probably don't want to write it every time you open a new terminal.

You can use keychain to remember the passphrase.

sudo apt install keychain

First of all some people use ssh-agent to add the SSH keys but you need to start one every time you open a new terminal and they don't die. So after some time you will end with a lot of ssh-agents running. If you did that you can step them with:

keychain --stop all

You can check that only one ssh-agent is running with ps -ef | grep ssh-agent

To set up keychain edit the ~/.bashrc file so that keychain is started everytime you open a terminal.

~/.bashrc
# Add this line at the end
eval `keychain --agents ssh --eval github_ssh`

github_ssh is the name of the SSH key to import you could add more separating them by spaces

3. Add the SSH key to github

This guide focus on github but you can do the same following similar steps for other git services like bitbucket.

  1. Copy the content of the ~/.ssh/github_ssh.pub file.
  2. Go to github settings page.
  3. Select SSH and GPG keys section.
  4. Click add new SSH keys.
  5. Use some meaningfull name like aws_ec2, paste the SSH key and save it.
  6. If asked, write your github password.

4. Check the SSH conection

Run the following command:

ssh -T git@github.com

The first time it will say that the authenticity of github.com can't be established. Enter yes to add it to the list of known hosts so that you won't get asked each time.

You should see a message saying Hi XXXX! You've successfully authenticated

5. Cloning a git repo

Since you are using SSH the clone command will change a little bit. Instead of using:

git clone https://github.com/username/repo_name.git

You should use:

git clone git@github.com:username/repo_name.git

After doing all that you can use git without needing to worry about passwords or passphrases anymore.