SSH Keys Management on Linux

Generate SSH Keys

• With ED25519 (Recommended)

ssh-keygen -t ed25519 -C "johndoe@email.com"

• With RSA

ssh-keygen -t rsa -b 4096 -C "johndoe@email.com"

Multiple SSH Keys Management

• Generate multiple SSH Keys for your multiple servers.
• When generating the keys use different filenames for different servers.
• Put the configs in the ~/.ssh/config file:

# Server 1
Host MyServer # Give a short name
HostName blog.somewebsite.com # Domain or IP
PreferredAuthentications publickey
IdentityFile ~/.ssh/id_rsa_somewebsite # The Private Key
User ubuntu # The username

# Server 2
Host c2 # Give a short name
HostName 172.117.93.121 # Domain or IP
PreferredAuthentications publickey
IdentityFile ~/.ssh/id_ed25519_secretserver # The Private Key
User root # The username

• When SSHing into a server simply provide the Host like this:

ssh MyServer

Note: Now, when you are cloning the repository (named demo) from the company’s GitHub account, the repository URL will be something like:

Repo URL: git@github.com:abc1234/demo.git

Now, while doing git clone, you should modify the above repository URL as:

git@company:abc1234/demo.git

Notice how github.com is now replaced with the alias “company” as we have defined in the configuration file.

Similary, you have to modify the clone URL of the repository in the personal account depending upon the alias provided in the configuration file.  

Transfer the public key securely

ssh-copy-id -i ~/.ssh/id_ed25519_secretserver.pub root@172.117.93.121