Using Multiple SSH Keys

Luciano Lima — Tue, 10 Oct 2023 16:51:48 +0000

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 "your_email@example.com"

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 "your_email@example.com"

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 "your_email@example.com"

For RSA

ssh-keygen -f ~/.ssh/id_rsa_gitlab -t ed25519 -C "your_email@example.com"

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 git@github.com and ssh -T git@gitlab.com 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.

DEV Community: Luciano Lima

Using Multiple SSH Keys

First Things First

Creating Your Keys

GitHub

GitLab

Add Your Keys To ssh-agent

Register your SSH Key

GitHub

Terminal

GitLab

Terminal

The Config File

Sometimes: ERROR

123 Testing