使用SSH协议，您可以连接和验证远程服务器和服务。使用SSH密钥，您可以在每次访问时无需提供用户名或密码即可连接到GitHub。

1. 在生成SSH密钥之前，您可以检查是否已存在SSH密钥。

在OpenSSH 7.0中不推荐使用DSA密钥,而使用RSA密钥。 例如，MacOS Sierra操作系统

$ cd ~/.ssh
$ ls -al ~/.ssh
total 40
drwxr-xr-x   6 apple  staff   192  6 12  2018 .
drwxr-xr-x+ 69 apple  staff  2208  2 20 13:36 ..
-rw-r--r--@  1 apple  staff  6148  6 12  2018 .DS_Store
-rw-------   1 apple  staff  1679  6 12  2018 id_rsa
-rw-r--r--   1 apple  staff   399  6 12  2018 id_rsa.pub 
-rw-r--r--   1 apple  staff   419  6 12  2018 known_hosts

.pub 文件是你的公钥，另一个则是私钥

2. 查看文件内容

$ cat ~/.ssh/id_rsa.pub

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDaAMofa59is3t5L7yzIxDiYsP1iLwTeeqARosE/AjXiZCQumFNlT+5b5qfPyWBT2vZGsP7QMUecPPJCmaCc61efUw/M8ES5gUi4MAIGETp8ovYDyEJOqnNDS6xE/+mForB98ONoMS4K5Tr+Z+DsEIGExyxrhBq6lSEk2xEVar1eOAbTNs+rzi9Mb1FxQ7Co+pliNisG8nTceKoCd67byxuJsjqebirWR8ZUDNytFdn55gI8zCFhzGzv+UL+VD10aL9PekfhFhltrnjydiKDmvfqdr6QN2WkG4N7MsERquIbIe7IKDvqTOU7G8lzLtopXuzqU78Fl0Wc0+8E+6vUTVF apple@grj-MacBookPro.local

$ cat ~/.ssh/id_rsa

-----BEGIN OPENSSH PRIVATE KEY-----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-----END OPENSSH PRIVATE KEY-----

$ cat ~/.ssh/known_hosts

[git.hb.cn]:9999,[192.168.0.199]:9999 ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDbcxiG0auRvY5d4asMyD8W/RoIJbeYEhuOLSeOhtJkfei3OT+fP5pk/n+Fyw2nj4RDANqrC/P4X/7Ja4zE5FE+lh3TgWiAFORHgfnuHqBI6ILinc8UbfsSbhzot3ASg6Z84augM5rBj8jP/Nt/rl7oXb1fu389HVcUmMGB1YLzc5XPH+3xlJ4aPGngmlfqB1BLuoyQS7Q1ubBsQzYk1ccggudks3cso+EvABDyAPYql03/NK+xB6IStFwTl2nKawscv9+e2+gMIcyvLKwZhuvXXptsgPXxtDhGCakj7yRqztp1UaF51cYMjc7folGajOTmf7S77iP1tK5dLpAk6twV

3. 创建新的

首先 ssh-keygen 会确认密钥的存储位置（默认是.ssh/id_rsa），然后它会要求你输入两次密钥口令。如果你不想在使用密钥时输入口令，将其留空即可.

$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/apple/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /Users/apple/.ssh/id_rsa.
Your public key has been saved in /Users/apple/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:NMh7hAvqSclzSwx82eHgYJmM5xdH237bZocBnxrCOqg apple@grj-MacBookPro.local
The key's randomart image is:
+---[RSA 2048]----+
| ooo..o          |
|.o=o.*.*         |
| oo =oB = .      |
| ..*.. B . o .   |
|  *.+ o S o +    |
| o = o o o = o   |
|  o o o   o = .  |
|   .   .   o .   |
|  E              |
+----[SHA256]-----+

关于在多种操作系统中生成 SSH 密钥的更深入教程，请参阅 GitHub 的 SSH 密钥指南