How to connect to the same host with different SSH keys?

Required Reading:

• Generate an SSH key pair

Optional Reading:

• None

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Setup your SSH configuration file

When connecting to a remote server via SSH, we would use the command line to specify the remote user name, hostname, and port, as shown below:

$ ssh [e-mail] -p 4321

We can connect to the server using the same options as in the previous command by typing ssh avengers after adding the following lines to your ~/.ssh/config:

Host avengers
    HostName avengers.com
    User tony
    Port 4321

We can also specify which SSH key to use when connecting to a specific server in the configuration file by setting IdentityFile:

Host avengers
    HostName avengers.com
    User tony
    Port 4321
    IdentityFile ~/.ssh/id_rsa_avengers

Host marvel
    HostName marvel.com
    User tony
    Port 8080
    IdentityFile ~/.ssh/id_rsa_marvel

The use of IdentityFile is especially useful when connecting to the same hostname with different SSH keys. A real-world example would be having multiple Github accounts, such as personal and work:

Host github_personal
    HostName github.com
    IdentityFile ~/.ssh/github_personal

Host github_work
    HostName github.com
    IdentityFile ~/.ssh/github_work

IdentityFile ~/.ssh/id_rsa 
#default ssh key to use for all other hosts

Using the configuration file above, we can clone repositories from your personal Github account with:

$ git clone git@github_personal:tonystark/ultron.git

Notice that instead of @github.com as the host name, we use @github_personal as defined in the configuration file.

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Updating the configuration file:

• Open your favorite terminal
• Create/Open the SSH configuration file

$ nano ~/.ssh/config

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Resources

• git config file syntax

Comments

[Christophe Colombier]

I found one typo

ssh ... -p 1234

Then

Port 4321

As you are repeating Port 4321, you should fix ssh -p 4321

[Jim Zandueta]

Thanks for the catch! 😄