ssh-keygen ssh-copy-id 无密码登陆

进行android开发经常需要登录远程ubuntu server服务器进行编译查看代码等，每次都需要输入密码，很烦人。

使用 ssh-keygen和ssh-copy-id配置一下就可以无需输入密码直接登录服务器了。

ssh-keygen 创建公钥和密钥。
ssh-copy-id 把本地主机的公钥复制到远程主机的authorized_keys文件上。
ssh-copy-id 也会给远程主机的用户主目录（home）和~/.ssh, 和~/.ssh/authorized_keys设置合适的权限 。

user@machine:~$ ssh-keygen -t rsa
Generating public/private rsa key pair.
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:
43:c6:7d:c4:9c:85:bd:8f:f0:5a:b7:8b:37:e6:e9:12 user@machine
The key's randomart image is:
+--[ RSA 2048]----+
|           o.=.  |
|       . . .= .  |
|        + . .  . |
|       o   .. .  |
|        S    o o |
|         .   E+ o|
|             o...|
|            ...=.|
|             .*=o|
+-----------------+
user@machine:~$ 
user@machine:~$ ls -l .ssh/
total 12
-rw------- 1 user user 1679 Sep  4 16:34 id_rsa
-rw-r--r-- 1 user user  393 Sep  4 16:34 id_rsa.pub
-rw-r--r-- 1 user user  222 Sep  3 13:03 known_hosts
user@machine:~$ ssh-copy-id -i .ssh/id_rsa.pub [email protected]
[email protected]'s password: 
Now try logging into the machine, with "ssh '[email protected]'", and check in:

  ~/.ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

user@machine:~$ ssh [email protected]