Linux上实现ssh免密码登陆远程服务器

Posted 2020-11-02

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	10.0.0.10	CentOS 6.5 x86
客户端	10.0.0.61	CentOS 6.5 x86

1.客户端生成密钥对

[[email protected] ~]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Created directory ‘/root/.ssh‘.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
99:af:26:b0:23:e2:04:9f:48:02:77:8a:d5:6d:b3:c7 [email protected]
The key‘s randomart image is:
+--[ RSA 2048]----+
| |
| . . |
|. o o + |
|.+ o . + o |
|+.. . E |
|+o .. . . |
|..o o . |
|o . o . .. |
|.o . . o. |
+-----------------+

查看生成的密钥对
[[email protected] ~]# 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：
[[email protected] ~]# scp .ssh/id_rsa.pub [email protected]:/root/
The authenticity of host ‘10.0.0.61 (10.0.0.61)‘ can‘t be established.
RSA key fingerprint is 83:c2:2d:85:79:f7:20:36:34:1d:53:1c:7a:b0:d9:bc.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added ‘10.0.0.61‘ (RSA) to the list of known hosts.
[email protected]‘s password:
id_rsa.pub 100% 394 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：

[[email protected] ~]# mkdir .ssh
[[email protected] ~]# cat id_rsa.pub >> .ssh/authorized_keys
[[email protected] ~]# chmod 600 .ssh/authorized_keys

4.修改ssh配置文件/etc/ssh/sshd_config，找到下面一行：

PubkeyAuthentication no
修改为：

PubkeyAuthentication yes

5.测试

[[email protected] ~]# ssh [email protected]
Last login: Wed May 2 13:39:22 2018 from 10.0.0.10
[[email protected] ~]#

6.注意事项

1. 在服务器端需要把selinux关闭，否则最后无法使用密钥进行远程登陆；
2. 客户端使用scp命令时，在服务器端也需要安装ssh客户端，否则无法把公钥上传到服务器端，另外也可以使用ssh-copy-id [email protected]来代替scp操作（这样在服务器端也不需要执行创建.ssh目录等这些操作，即相当于该命令可以一步帮我们完成密钥的上传与配置工作）；