SSH Connection Failure to Git Repository: Hostname Resolution Error Analysis and Solutions

Error Phenomenon and Background

When developers switch their Git repository access method from HTTPS to SSH, they often encounter the following error message:

ssh: Could not resolve hostname git: Name or service not known
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

This error indicates that the system cannot resolve the hostname "git", preventing the establishment of an SSH connection to the remote repository. This situation typically occurs after configuration changes and requires systematic inspection of multiple components.

Core Problem Analysis

This error primarily involves issues at several technical levels:

Incorrect Remote Repository URL Configuration

The most common cause is an improperly formatted remote repository URL. Use the git remote -v command to view the currently configured remote repository addresses:

$ git remote -v
origin  https://git@github.com:userName/repo.git (fetch)
origin  https://git@github.com:userName/repo.git (push)

If HTTPS-formatted URLs are displayed, they need to be modified to the correct SSH format.

SSH Configuration Issues

SSH connections rely on proper key configuration and authentication mechanisms. Ensure that:

• SSH keys are correctly generated and added to ssh-agent
• Public keys are uploaded to the GitLab/GitHub account
• Relevant host configurations are not missing in the SSH config file (~/.ssh/config)

Network and DNS Resolution

Network connectivity issues or DNS resolution failures can also cause this error:

• Network connection interruptions or instability
• DNS servers unable to resolve the "git" hostname
• Firewalls or proxy servers blocking SSH connections
• VPN connection problems (e.g., not connected to corporate VPN)

Solutions and Implementation Steps

Check and Correct Remote Repository URL

First, verify the current remote repository configuration, then use the correct SSH-formatted URL:

$ git remote set-url origin git@github.com:userName/repo.git

Verify the modification result:

$ git remote -v
origin  git@github.com:userName/repo.git (fetch)
origin  git@github.com:userName/repo.git (push)

The correct SSH URL format should be git@hostname:username/repository.git, where hostname depends on the Git service provider used (e.g., github.com, gitlab.com).

SSH Configuration Verification

Test whether the SSH connection can be established normally:

$ ssh -T git@github.com

If the connection is successful, a welcome message will be displayed. If it fails, check:

• Whether SSH keys exist: ls -la ~/.ssh/
• Whether keys are added to ssh-agent: ssh-add -l
• Whether public keys are added to the Git service provider account

Network and DNS Troubleshooting

Use network diagnostic tools to check connection status:

$ ping github.com
$ nslookup github.com

If DNS resolution fails, try:

• Changing DNS servers
• Checking local hosts file configuration
• Verifying network proxy settings
• Confirming VPN connection status (if applicable)

Complete Troubleshooting Procedure

1. Run git remote -v to check current remote configuration
2. If necessary, use git remote set-url to correct the URL
3. Test SSH connection: ssh -T git@hostname
4. Check network connectivity and DNS resolution
5. Verify firewall and proxy settings
6. Confirm SSH key configuration is correct

Preventive Measures and Best Practices

To avoid similar issues, it is recommended to:

• Back up important configurations before switching protocols
• Use version control to manage SSH configuration changes
• Establish standard repository URL naming conventions
• Regularly test SSH connection status
• Document Git configuration standards within the team

Through systematic troubleshooting and standardized configuration management, SSH connection-related issues can be effectively avoided, ensuring smooth development work.