Using Multiple SSH Keys

Hi everyone! This is my first post and I'm here to talk about SSH and the pain it is to use it sometimes. So let's go directly to the point. Have you ever had the feeling you can´t use GitHub and GitLab at the same time on your devices through SSH? Well, you can!

First Things First

Enter ls -al ~/.ssh and if the output is like

id_rsa.pub
id_ecdsa.pub
id_ed25519.pub

It means that you have the folder we need and also you already have the default keys in place (we're not using those).

Creating Your Keys

GitHub

On your terminal enter

ssh-keygen -f ~/.ssh/id_ed25519_github -t ed25519 -C "[e-mail]"

For some old systems you'll have to use RSA, so do this instead

ssh-keygen -f ~/.ssh/id_rsa_github -t rsa -b 4096 -C "[e-mail]"

In both ways, they're gonna ask you for names and passwords but I just press ENTER and move on.

GitLab

Same thing. At terminal we enter

ssh-keygen -f ~/.ssh/id_ed25519_gitlab -t ed25519 -C "[e-mail]"

For RSA

ssh-keygen -f ~/.ssh/id_rsa_gitlab -t ed25519 -C "[e-mail]"

Add Your Keys To ssh-agent

Be sure that it is running

eval `ssh-agent -s`

And now enter the name of the keys you registered
GitHub

ssh-add ~/.ssh/id_ed25519_github

GitLab

ssh-add ~/.ssh/id_ed25519_gitlab

ATTENTION: If you're using the RSA one be sure to put the correct names of the files.

Register your SSH Key

GitHub

Terminal

• Enter the ssh filter with cd ~/.ssh
• Type cat id_ed25519_github.pub
• Copy the content #### Web Site
• Click your photo profile
• Settings
• SSH and GPG Keys
• New SSH Key
• Give the registry a name on the Title
• Paste the key that you copied from the terminal on the key
• Add SSH Key

GitLab

Terminal

• Enter the ssh filter with cd ~/.ssh
• Type cat id_ed25519_gitlab.pub
• Copy the content #### Web Site
• Click your photo profile
• Settings
• SSH Keys
• Paste the key that you copied from the terminal on the key
• Give the registry a name on the Title
• Add key

The Config File

Now is the tricky part. When you're using the keys on .ssh there is no config file so you need to create one.

• Enter the .ssh folder with cd ~/.ssh
• Create a file with touch config
• Now open the file with nano config
• Paste the configuration below

# GITHUB
Host github.com
   HostName github.com
   PreferredAuthentications publickey
   IdentityFile ~/.ssh/id_ed25519_github

# GITLAB
Host gitlab.com
   HostName gitlab.com
   PreferredAuthentications publickey
   IdentityFile ~/.ssh/id_ed25519_gitlab

Sometimes: ERROR

GitHub likes to make us lose some hair over configuration and sometimes you'll get some errors like:

kex_exchange_identification: read: connection reset by peer ubuntu

If the error has kex_exchange_identification try these changes on the config file:

# GITHUB
Host github.com
   HostName ssh.github.com
   PreferredAuthentications publickey
   IdentityFile ~/.ssh/id_ed25519_github
   Port 443
   User git

# GITLAB
Host gitlab.com
   HostName gitlab.com
   PreferredAuthentications publickey
   IdentityFile ~/.ssh/id_ed25519_gitlab

If you set the port to 443 and put the "ssh." on HostName

Also, there is this annoying possibility you get a permission error. To fix that set your config file to 600:

cd ~/.ssh
chmod 600 config

123 Testing

Now you try ssh -T [e-mail] and ssh -T [e-mail] and see if the message is a friendly one.

The best part is that you can add more versioning sites to use your keys and help with productivity (and also you'll be way less annoyed :) )

PS: If you're still getting errors like the "bad owner or permission" one, try chmod 600 ~/.ssh/config.