Creating SSH Keys

How to generate a public/private key pair for GitHub or for remote SSH access.

Key Location

List existing keys under ~/.ssh. If any are present, you will see an output similar to this:

ls -l ~/.ssh

total 12
-rw------- 1 user user 3243 jun  1 15:05 id_rsa
-rw------- 1 user user  742 jun  1 15:05 id_rsa.pub
-rw-r--r-- 1 user user 1326 Jun  1 15:05 known_hosts

Create a New Key Pair

In this example we will generate the id_rsa key pair.

Generate a new SSH key.

ssh-keygen -t rsa -b 4096 -C "user@example.com"

Enter file in which to save the key (/home/user/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/user/.ssh/id_rsa.
Your public key has been saved in /home/user/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:xCYt9XPANH0jk76Td96cU1m1D2htEPamHfu8lWce5Kk user@example.com
The key's randomart image is:
+---[RSA 4096]----+
|        .o+.oo   |
|       + ..+*.o .|
|      o = o..B+.o|
|       =   o++++.|
|        S  ..+oo+|
|            + ++*|
|             o OX|
|              .=O|
|             E .o|
+----[SHA256]-----+

Start the SSH agent.
```
eval "$(ssh-agent -s)"
```
```
Agent pid 19690
```

Add the private key to the agent.

ssh-add ~/.ssh/id_rsa

Identity added: /home/user/.ssh/id_rsa (/home/user/.ssh/id_rsa)

Usage

Copy the public key id_rsa.pub.

cat ~/.ssh/id_rsa.pub

ssh-rsa AAAAB3NzaC1yc2EAAAAF...MLZ94Nq2F4ToHR3U6Q== user@example.com

Paste the public key wherever it is required.

For GitHub, go to Settings > SSH and GPG keys.
To allow remote access on another server, append the key to the authorized_keys file inside ~/.ssh.
```
cd /home/server/.ssh
```
```
nano authorized_keys
```

Permissions for the Key Directory

Secure the permissions for the directory and its files.

sudo chmod 600 -R ~/.ssh/*

sudo chmod 644 ~/.ssh/known_hosts

sudo chmod 755 ~/.ssh

References

bash key chmod

Published: June 1, 2020