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Create An SSH Key

An SSH key uniquely identifies you (and your computer) when your computer is communicating with other computers. Think of an SSH key as a fancy password.

You'll need one of these to create your Github account.

Option 1: Do you have a preexisting SSH key for some other reason?

Maybe you went to a previous RailsBridge workshop, or generated an SSH key to push some code to GitHub? You can check with the following command:

Type this in the terminal:
ls ~/.ssh/id_rsa

If you see the message No such file or directory, you don't have an SSH key yet.

'No such file or directory'
'/Users/[something]/.ssh/id_rsa'

Option 2: Generate an SSH key

Use the same email address for git, github, and ssh.

REPLACE student@example.com with your actual email address below.

Type this in the terminal:
ssh-keygen -C student@example.com -t rsa

Press enter to accept the default key save location.

Next, you'll be asked for a passphrase.

Choose whether to use a passphrase

No passphrase

Hit enter to accept blank passphrase, then hit enter again.

Passphrase

If your computer is shared with other people, as in a work laptop, you should choose and enter a real passphrase. Twice.

After key generation is complete, you'll have output that looks like this.

Expected result:
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/student/.ssh/id_rsa):
Created directory '/Users/student/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /Users/student/.ssh/id_rsa.
Your public key has been saved in /Users/student/.ssh/id_rsa.pub.
The key fingerprint is:
88:54:ab:77:fe:5c:c3:7s:14:37:28:8c:1d:ef:2a:8d student@example.com

Verify

Your brand-new public key is now stored at ~/.ssh/id_rsa.pub

Public vs. Private Keys

If you look inside ~/.ssh/, you will notice two files with the same name: id_rsa and id_rsa.pub.

id_rsa.pub is your public key and can be shared freely.

id_rsa is your private key and must be kept secret.

If someone else gets your private key and your passphrase, then they can pretend to be you and log on to your Heroku or Github accounts and cause mischief!

Add your generated key to the authentication agent using the following command:

Type this in the terminal:
ssh-add ~/.ssh/id_rsa
Expected result:
Enter passphrase for /Users/student/.ssh/id_rsa:
Identity added: /Users/student/.ssh/id_rsa (/Users/student/.ssh/id_rsa)"

Could not open a connection to your authentication agent

If the ssh-agent is not running, you will come across this error. Here are a few commands that you can try to use to start the ssh-agent:

For some Windows machines:
eval `ssh-agent -s`
For others (confirmed on some Windows 7, 8, 8.1, and 10 setups):
eval $(ssh-agent)
For Linux:
eval `ssh-agent`

For additional options, this StackOverflow thread has been helpful: http://stackoverflow.com/questions/17846529/could-not-open-a-connection-to-your-authentication-agent

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