# About create SSH key on Ubuntu
refference : [How to Set Up SSH Keys on Ubuntu 20.04](https://linuxize.com/post/how-to-set-up-ssh-keys-on-ubuntu-20-04/)
---
## Creating SSH keys on Ubuntu
1. To check whether the key files exist.
```linux
$ ls -l ~/.ssh/id_*.pub
```
2. To generate SSH key pair with your email
```linux
$ ssh-keygen -t rsa -C "your_email@domain.com"
```
* Or you can set the SSH key size
```linux
$ ssh-keygen -i rsa -b 4096 -C "your _email@domain.com"
```
3. Save the key file
```
Enter file in which to save the key (/Users/[you]/.ssh/id_rsa): [Press enter]
```
* You can change the file name ex: xxx_rsa
4. SSH program will ask you to enter passphrase
```
Enter passphrase (empty for no passphrase):
```
5. Show the fingerprint
```
SHA256:********* your@email
```
## We have to use ssh-agent to control our ssh key
reference:[ssh-agent introduction](https://www.ssh.com/academy/ssh/agent)
* ssh-agent is a program on Linux systems
1. Starting ssh-agent on linux
```linux
$eval `ssh-agent -s`
Agent pid *****
```
* use "eval" to execute the ssh-agent
2. Add the rsa key into ssh-agent
```
$ssh-add ~/.ssh/id_rsa
```
* You can choose the key files
* Now you can use your SSH key on Ubuntu