To give secure access to private GitHub repositories on less-trusted systems like CI or HPC or shared workstation, consider GitHub Oauth tokens. The Oauth token can give read-only (or other fine-grained permissions) to all or a specific subset of repositories the GitHub account has access to.

Create a GitHub Oauth token with the desired permissions.

For read-only private GitHub repo access the “repo” permission group is selected.

Copy the text string token and SSH into the remote system where access is desired. Configure the global user Git config to use the Oauth token for the desired GitHub organization or user.

Suppose a coworker “sara” has a private GitHub repo “myrepo” and has added your GitHub username as a collaborator in the “myrepo” settings. On the remote computer, configure Git to use the Oauth token for the “sara” GitHub user:

git config --global url.https://oauth2:OauthToken@github.com/sara/.insteadOf https://github.com/sara/

A similar syntax is used for GitHub organizations or specific repositories.

The text OauthToken is replaced with the actual Oauth token string from GitHub.

Related: Git pull HTTPS push SSH