Linux中SSH服务（二）

一、基于公私钥的认证（免密登录）

1、Windows免密登录Linux

Windows推荐安装Cygwin软件：Cygwin

1.1Windows上面生成公私钥

之前已经生成过了，所以显示公私钥已存在
lovezyw@LAPTOP-AABHB5ED ~
$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/lovezyw/.ssh/id_rsa):
/home/lovezyw/.ssh/id_rsa already exists.
Overwrite (y/n)?


lovezyw@LAPTOP-AABHB5ED ~
$ ls ~/.ssh/
id_rsa  id_rsa.pub  known_hosts

2.2公钥发送给服务端

Windows上操作
$ ssh-copy-id [email protected]


Linux服务端查看
[master-61 root ~] # ls .ssh/ -l
total 12
-rw------- 1 root root  577 Jan  8 15:37 authorized_keys

3.3可以进行免密登录

2、linux免密登录linux

准备机器

master-61 10.0.0.61

web-7 10.0.0.7

2.1在master-61机器生成公私钥

[master-61 root ~] # ssh-keygen 
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
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:
SHA256:P34ShRM0e2AfzlmhqWDG5RDqWY7zCHKx8QpbXe3rs4o root@master-61
The key's randomart image is:
+---[RSA 2048]----+
|        oo* . o. |
|       o *.B *   |
|    o . B +oO    |
|     B O ooo.    |
|  o = B S oo     |
|   * o + ...     |
|  . . . . +.     |
|       . oo..    |
|      E ..+=     |
+----[SHA256]-----+
[master-61 root ~] # ls .ssh/ -l
total 12
-rw------- 1 root root  577 Jan  8 15:37 authorized_keys
-rw------- 1 root root 1679 Jan  8 15:54 id_rsa
-rw-r--r-- 1 root root  396 Jan  8 15:54 id_rsa.pub

2.2 发送master-61的公钥给web-7，并核对公钥是否一样

master-61机器上操作
[master-61 root ~] # ssh-copy-id [email protected]
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host '10.0.0.7 (10.0.0.7)' can't be established.
ECDSA key fingerprint is SHA256:p+Y8oREDmNYotbNk8uqZv6KTTFKFnLhOxXp3D+Jet6Q.
ECDSA key fingerprint is MD5:d4:45:1d:1c:9f:5f:9f:8e:c7:86:d3:03:ee:f1:78:f4.
Are you sure you want to continue connecting (yes/no)? yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
[email protected]'s password: 

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh '[email protected]'"
and check to make sure that only the key(s) you wanted were added.

[master-61 root ~] # cat ~/.ssh/id_rsa.pub 
ssh-rsa AAAAB3NzaC1yc2EAAAADAQAAABAQDghdixJEHOiWLHPuGuRpyWMPTo/ADq7em9Toc0l/fiiZ9g2uuhpBgbJwPaN7kcKcKDpVNSNloVVDGQpg38gvShEvM0Z7Xf9WKp2ZNv6rAnGMTPphfMq85/MQl2nHzD/sU5AIugoZBdx9qL02+7UAowpXBE7HCU+lenIFTULI5RZu3CADEaMhKziBZkthjPO4gUWmfs09YaVLQTETYuAvOwitXQzTDjQFlv8chK59YGXWeY/JYX2CUcY6xcwjVgsqg1uPG+DUWGnehNg/SWiHFMkxT/Pb5jMVtTE2HefHholNt32+ujD+b5d5D4Od8FONBt8WwSRooGPP/ root@master-61



web-7机器上检查公钥
[web-7 root ~] # ll .ssh
ls: cannot access .ssh: No such file or directory
[web-7 root ~] # ll .ssh/
total 4
-rw------- 1 root root 396 Jan  8 15:59 authorized_keys
[web-7 root ~] # 
[web-7 root ~] # cat ~/.ssh/authorized_keys 
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDghdixJEHOiWLHPuGuRpyWMPTo/ADq7em9Toc0l/fiiZ9g2uuhpBgbJwPaN7kcKcKDpVNSNloVVDGQpg38gvShEvM0Z7Xf9WKp2ZNv6rAnGMTPphfMq85/MQl2nHzD/sU5AIugoZBdx9qL02+7UAowpXBE7HCU+lenIFTULI5QuPRZu3CADEaMhKziBZkthjPO4gUWmfs09qzcIzMYaVLQTETYuAvOwitXQzTDjQFlv8chK59YGXWeY/JYX2CUcY6xcwjVgsqg1uPG+DUWGnehNg/SWiHFMkxT/Pb5jMVtTE2HefHholNt32+ujD+b5d5D4Od8FONBt8WwSRooGPP/ root@master-61
[web-7 root ~] # 

2.3登录测试免密

[master-61 root ~] # ssh [email protected]
Last login: Wed Jan  8 15:58:02 2025 from 10.0.0.1
[web-7 root ~] # 

二、SSH文件权限

1、~/.ssh/config 配置文件的使用（方便快捷登录）

~/.ssh/config 文件允许你为不同的主机或服务器配置特定的选项

配置文件示例

Host test

HostName 10.0.0.1

User root

Port 22

IdentityFile ~/.ssh/id_rsa

常用参数

Host：指定别名或通配符，允许为多个主机配置共同的选项。例如，Host * 可以匹配所有主机。

HostName：指定主机的 IP 地址或域名。

User：指定用户名。

Port：指定连接的端口号。

IdentityFile：指定 SSH 私钥文件。

ForwardAgent：是否启用 SSH 代理转发。默认是 no。

Compression：是否启用压缩，通常设置为 yes 可以加速连接，尤其是在低带宽环境下

2、文件权限设置

ssh文件对应权限如下

chmod 700 ~/.ssh

chmod 600 ~/.ssh/id_rsa

chmod 644 ~/.ssh/id_rsa.pub

chmod 600 ~/.ssh/config

3、登录测试

master-61机器相关文件和权限都配置好，直接ssh web-7登录
注：确保master-61的公钥传送到web-7机器上了
[master-61 root ~] # ssh-copy-id [email protected]
[master-61 root ~] # ll .ssh/
total 20
-rw------- 1 root root  577 Jan  8 15:37 authorized_keys
-rw------- 1 root root   92 Jan  9 08:58 config
-rw------- 1 root root 1679 Jan  8 15:54 id_rsa
-rw-r--r-- 1 root root  396 Jan  8 15:54 id_rsa.pub
-rw-r--r-- 1 root root  170 Jan  8 15:59 known_hosts
[master-61 root ~] # 
[master-61 root ~] # cat .ssh/config 
Host web-7
  HostName 10.0.0.7
  User root
  Port 22
[master-61 root ~] # ssh web-7
Last login: Thu Jan  9 08:59:00 2025 from 10.0.0.61
[web-7 root ~] #