Many developers who work with multiple servers face this situation: your primary SSH connections use a custom port (like 1234) configured in ~/.ssh/config, but GitHub strictly uses port 22. When your default SSH config specifies a non-standard port, Git operations fail with connection errors.

The issue occurs because SSH applies the global port setting to all connections unless specifically overridden. Here's what happens when your config contains:

# ~/.ssh/config
Port 1234
Host *
  User git

This makes all SSH connections (including GitHub) attempt to use port 1234.

1. Host-Specific SSH Configuration

The cleanest solution is to modify your SSH config to handle GitHub separately:

# ~/.ssh/config
# Default settings for your servers
Host mydomain.com
  Port 1234
  User admin

# GitHub-specific settings
Host github.com
  HostName github.com
  User git
  Port 22
  IdentityFile ~/.ssh/github_key

2. URL-Based Port Specification

For one-off cases, you can modify the Git remote URL:

[remote "origin"]
    url = ssh://git@github.com:22/asdf/asdf.git

3. SSH Config Inheritance

If you have multiple GitHub accounts or special cases, use pattern matching:

Host github.com
  HostName github.com
  User git
  Port 22

Host github-work
  HostName github.com
  User git
  Port 22
  IdentityFile ~/.ssh/work_key

Host *
  Port 1234

Test your configuration with:

ssh -T git@github.com

You should see GitHub's success message without port-related errors.

For developers managing both personal and work repositories:

# Personal account
Host github.com-personal
  HostName github.com
  User git
  Port 22
  IdentityFile ~/.ssh/id_ed25519_personal

# Work account
Host github.com-work
  HostName github.com
  User git
  Port 22
  IdentityFile ~/.ssh/id_ed25519_work

# Default for other servers
Host *
  Port 1234

Then configure Git remotes accordingly:

[remote "origin"]
    url = git@github.com-work:company/project.git

---

Many developers working with multiple servers configure a default non-standard SSH port (like 1234) in their ~/.ssh/config for security reasons:

Host *
    Port 1234

This creates conflicts when connecting to GitHub, which exclusively uses port 22. The global setting forces all SSH connections (including GitHub) to use port 1234, resulting in connection failures.

The solution lies in SSH's host-specific configuration capabilities. Here's the proper way to structure your config file:

# Default configuration for most servers
Host *
    Port 1234
    ForwardAgent yes

# GitHub specific configuration
Host github.com
    HostName github.com
    User git
    Port 22
    IdentityFile ~/.ssh/github_key

Ensure your Git remote URLs use the SSH protocol format. Both these formats work with the above configuration:

git@github.com:user/repo.git
ssh://git@github.com:22/user/repo.git

For existing repositories, update the URL with:

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

Verify your configuration works by testing the SSH connection:

ssh -T git@github.com

If you encounter issues, use verbose mode for debugging:

ssh -Tv git@github.com

For developers managing multiple GitHub accounts with different SSH keys, extend the configuration:

Host github-work
    HostName github.com
    User git
    Port 22
    IdentityFile ~/.ssh/work_github_key

Host github-personal
    HostName github.com
    User git
    Port 22
    IdentityFile ~/.ssh/personal_github_key

Then use these custom hosts in your Git remotes:

[remote "origin"]
    url = git@github-work:company/project.git