Generating SSH keys

• 2015-02-03
• 2783 View

Step 1: Check for SSH keys

First, we need to check for existing SSH keys on your computer. Open up your Terminal and type:

ls -al ~/.ssh
# Lists the files in your .ssh directory, if they exist

Check the directory listing to see if you already have a public SSH key. The default public key file names are:

• id_dsa.pub
• id_ecdsa.pub
• id_ed25519.pub
• id_rsa.pub

Step 2: Generate a new SSH key

To generate a new SSH key, copy and paste the text below, making sure to substitute in your email address. The default settings are preferred, so when you're prompted to "Enter a file in which to save the key", just press Enter to continue.

ssh-keygen -t rsa -C "your_email@example.com"
# Creates a new ssh key, using the provided email as a label
# Generating public/private rsa key pair.
# Enter file in which to save the key (/home/you/.ssh/id_rsa):

Next, you'll be asked to enter a passphrase.

# Enter passphrase (empty for no passphrase): [Type a passphrase]
# Enter same passphrase again: [Type passphrase again]

Which should give you something like this:

# Your identification has been saved in /home/you/.ssh/id_rsa.
# Your public key has been saved in /home/you/.ssh/id_rsa.pub.
# The key fingerprint is:
# 01:0f:f4:3b:ca:85:d6:17:a1:7d:f0:68:9d:f0:a2:db your_email@example.com

Then add your new key to the ssh-agent:

# start the ssh-agent in the background
eval "$(ssh-agent -s)"
# Agent pid 59566
ssh-add ~/.ssh/id_rsa

Step 3: Add your SSH key to your account

sudo apt-get install xclip
# Downloads and installs xclip. If you don't have `apt-get`, you might need to use another installer (like `yum`)

xclip -sel clip < ~/.ssh/id_rsa.pub
# Copies the contents of the id_rsa.pub file to your clipboard

Now that you have the key copied, it's time to add it to GitHub:

1. In the top right corner of any page, click .

2. In the user settings sidebar, click SSH keys.

3. Click Add SSH key.

4. In the Title field, add a descriptive label for the new key. For example, if you're using a personal Mac, you might call this key "Personal MacBook Air".
5. Paste your key into the "Key" field.
6. Click Add key.
7. Confirm the action by entering your GitHub password.

Step 4: Test everything out

To make sure everything is working, you'll now try SSHing to GitHub. When you do this, you will be asked to authenticate this action using your password, which was the passphrase you created earlier.

Open up your Terminal and type:

ssh -T git@github.com
# Attempts to ssh to GitHub

...
Agent admitted failure to sign using the key.
debug1: No more authentication methods to try.
Permission denied (publickey).

You may see this warning:

# The authenticity of host 'github.com (207.97.227.239)' can't be established.
# RSA key fingerprint is 16:27:ac:a5:76:28:2d:36:63:1b:56:4d:eb:df:a6:48.
# Are you sure you want to continue connecting (yes/no)?

Don't worry! This is supposed to happen. Verify that the fingerprint in your terminal matches the one we've provided up above, and then type "yes."

# Hi username! You've successfully authenticated, but GitHub does not
# provide shell access.

If that username is yours, you've successfully set up your SSH key! Don't worry about the "shell access" thing, you don't want that anyway.

If you receive a message about "access denied," you can read these instructions for diagnosing the issue.

If you're switching from HTTPS to SSH, you'll now need to update your remote repository URLs. For more information, see Changing a remote's URL.