0.说明
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平常使用ssh登陆远程服务器时，都需要使用输入密码，希望可以实现通过密钥登陆而免除输入密码，从而可以为以后实现批量自动部署主机做好准备。
环境如下：
| IP地址 | 操作系统 |
| 服务器端 | 10.0.0.128/24 | CentOS 6.5 x86 |
| 客户端 | 10.0.0.129/24 | Ubuntu 16.04 x86 |
1.客户端生成密钥对
生成密钥对：
xpleaf@leaf:~$ ssh-keygen -t rsa -b 2048
Generating public/private rsa key pair.
Enter file in which to save the key (/home/xpleaf/.ssh/id_rsa):
Created directory '/home/xpleaf/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/xpleaf/.ssh/id_rsa.
Your public key has been saved in /home/xpleaf/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:eLssyXJLzUCfSN5mu6nqNH9dB/gOyXSvWBwQDNSsIYE xpleaf@leaf
The key's randomart p_w_picpath is:
+---[RSA 2048]----+
| o=oo |
| E .o = |
| o oo o |
| + = .o +. |
| = So = + |
| B o+ = o |
| o...=. * o |
| ..+=..+o o |
| .o++== |
+----[SHA256]-----+
查看生成的密钥对：
xpleaf@leaf:~$ ls .ssh
id_rsa id_rsa.pub
# id_rsa为私钥，这个一般需要保密；id_rsa.pub为公钥，这个可以公开。
2.上传公钥到服务器端
使用scp命令操作：
xpleaf@leaf:~$ scp .ssh/id_rsa.pub root@10.0.0.128:/root
The authenticity of host '10.0.0.128 (10.0.0.128)' can't be established.
RSA key fingerprint is SHA256:0Tpm11wruaQXyvOfEB1maIkEwxmjT2AklWb198Vrln0.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '10.0.0.128' (RSA) to the list of known hosts.
root@10.0.0.128's password:
id_rsa.pub 100% 393 0.4KB/s 00:00
3.服务器端操作
把从客户端传来的公钥添加到.ssh/authorized_keys中：
[root@leaf ~]# cat id_rsa.pub >> .ssh/authorized_keys
[root@leaf ~]# chmod 600 .ssh/authorized_keys
# authorized_keys的权限需要为600
修改ssh配置文件/etc/ssh/sshd_config，找到下面一行：
PubkeyAuthentication no
修改为：
PubkeyAuthentication yes
4.测试
在客户端上使用密钥登陆到服务器上：
xpleaf@leaf:~$ ssh -i .ssh/id_rsa root@10.0.0.128
Last login: Tue May 9 15:14:01 2017 from 10.0.0.129
[root@leaf ~]#
5.注意事项
网站题目：Linux上实现ssh免密码登陆远程服务器
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http://cdkjz.cn/article/pjhdgc.html
