It is better to have different keys for each machine you access Github from. In order to generate the keys, ssh-keygen needs to be installed to the system.

This is the only way to connect to Github if not using an Enterprise account or the Github CLI.

More detailed instructions can be found on the official pages here and here.

Generate

Open a terminal and run the following command:

ssh-keygen -t ed25519 -C "your_email@example.com"

When prompted about the location and file name to save the key to, keep in mind that leaving the default (just pressing Enter) will overwrite any existing keys with the same file name:

> Enter a file in which to save the key (/home/USER/.ssh/id_ALGORITHM):[Press enter]

Using a passphrase is recommended by not required:

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

Add to the agent

Start the agent in the background by running:

$ eval "$(ssh-agent -s)"
> Agent pid 12345

Then proceed with adding to the agent:

ssh-add ~/.ssh/id_ALGORITHM

Finally, the public key needs to be added to your Github account. To do this, first get a copy of the content of the public key file:

cat ~/.ssh/id_ALGORITHM.pub

or open it in a text editor.

Once the copy is in the clipboard, open the Settings page of your Github account and go to Access > SSH and GPG keys. Fill in the relevant fields to complete the process.