Connect with SSH. Troubleshooting SSH. Verify commit signatures. Troubleshoot verification. Checking for existing SSH keys. Note: GitHub is improving security by dropping older, insecure key types. Did this doc help you? Help us make these docs great! Make a contribution Or, learn how to contribute. The associated public key can be shared freely without any negative consequences. The public key can be used to encrypt messages that only the private key can decrypt. This property is employed as a way of authenticating using the key pair.
The public key is uploaded to a remote server that you want to be able to log into with SSH. When a client attempts to authenticate using SSH keys, the server can test the client on whether they are in possession of the private key. If the client can prove that it owns the private key, a shell session is spawned or the requested command is executed. The first step to configure SSH key authentication to your server is to generate an SSH key pair on your local computer.
To do this, we can use a special utility called ssh-keygen , which is included with the standard OpenSSH suite of tools. By default, this will create a bit RSA key pair. The utility will prompt you to select a location for the keys that will be generated. Usually, it is best to stick with the default location at this stage. If you would like to choose a non-standard path, type that in now, otherwise, press ENTER to accept the default.
If you choose to overwrite the key on disk, you will not be able to authenticate using the previous key anymore. Be very careful when selecting yes, as this is a destructive process that cannot be reversed. Next, you will be prompted to enter a passphrase for the key.
This is an optional passphrase that can be used to encrypt the private key file on disk. You may be wondering what advantages an SSH key provides if you still need to enter a passphrase. Some of the advantages are:. Since the private key is never exposed to the network and is protected through file permissions, this file should never be accessible to anyone other than you and the root user. The passphrase serves as an additional layer of protection in case these conditions are compromised.
A passphrase is an optional addition. If you enter one, you will have to provide it every time you use this key unless you are running SSH agent software that stores the decrypted key.
We recommend using a passphrase, but if you do not want to set a passphrase, you can press ENTER to bypass this prompt. You now have a public and private key that you can use to authenticate. The next step is to place the public key on your server so that you can use SSH key authentication to log in.
Note: a previous version of this tutorial had instructions for adding an SSH public key to your DigitalOcean account. There are multiple ways to upload your public key to your remote SSH server. The method you use depends largely on the tools you have available and the details of your current configuration. The following methods all yield the same end result. The simplest, most automated method is described first, and the ones that follow it each require additional manual steps.
You should follow these only if you are unable to use the preceding methods. The simplest way to copy your public key to an existing server is to use a utility called ssh-copy-id. Because of its simplicity, this method is recommended if available. The server can then use its copy of the public key to verify the signature. We welcome your input on features and topics that you would like to see included on this website. Please send us email with your wish list and other feedback.
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