ssh服务登录的常用验证方式

• 用户/口令
• 基于密钥

基于用户和口令登录验证

1. 客户端发起ssh请求，服务器会把自己的公钥发送给用户
2. 用户会根据服务器发来的公钥对密码进行加密
3. 加密后的信息回传给服务器，服务器用自己的私钥解密，如果密码正确，则用户登录成功

基于密钥的登录方式

1. 首先在客户端生成一对密钥（ssh-keygen）
2. 并将客户端的公钥ssh-copy-id 拷贝到服务端
3. 当客户端再次发送一个连接请求，包括ip、用户名
4. 服务端得到客户端的请求后，会到authorized_keys中查找，如果有响应的IP和用户，就会随机生 成一个字符串。
5. 服务端将使用客户端拷贝过来的公钥进行加密，然后发送给客户端
6. 得到服务端发来的消息后，客户端会使用私钥进行解密，然后将解密后的字符串发送给服务端
7. 服务端接受到客户端发来的字符串后，跟之前的字符串进行对比，如果一致，就允许免密码登录

实现基于密钥的登录方式

再客户端生成密钥对

ssh-keygen -t rsa [-P 'password'] [-f “~/.ssh/id_rsa"]

把公钥文件传输至远程服务器对应用户的家目录

ssh-copy-id [-i [identity_file]] [user@]host

重设私钥口令：

ssh-keygen -p

验证代理（authentication agent）保密解密后的密钥，口令就只需要输入一次，在GNOME中，代理被 自动提供给root用户

#启用代理
ssh-agent bash
#钥匙通过命令添加给代理
ssh-add

在SecureCRT或Xshell实现基于key验证

在SecureCRT工具—>创建公钥—>生成Identity.pub文件

转化为openssh兼容格式（适合SecureCRT，Xshell不需要转化格式），并复制到需登录主机上相应文件authorized_keys中,注意权限必须为600，在需登录的ssh主机上执行：

ssh-keygen -i -f Identity.pub >> .ssh/authorized_keys

示例：实现key验证

1、生成密钥文件

[root@centos7-liyj ~]#ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): #回车，默认值
Created directory '/root/.ssh'.
Enter passphrase (empty for no passphrase): #回车，默认值，空密码
Enter same passphrase again: #回车，默认值
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:beb76jlNwNgyAjqbZWDfqwAUibQejOj/8GbU6cU1SeQ root@centos7-liyj
The key's randomart image is:
+---[RSA 2048]----+
|ooo .. |
|=o+ . .. |
|+= + o +.E. |
|+ + + o +.++ |
| + * .oSo=.. |
| = ..o * . |
| +… . .o |
| =o . .o. |
| oo .=+. |
+----[SHA256]-----+

[root@centos7-liyj ~]#tree .ssh/
.ssh/
├── id_rsa
└── id_rsa.pub

0 directories, 2 files
[root@centos7-liyj ~]#ll .ssh/
total 8
-rw------- 1 root root 1675 Apr 29 15:32 id_rsa
-rw-r--r-- 1 root root 399 Apr 29 15:32 id_rsa.pub
[root@centos7-liyj ~]#cat .ssh/id_rsa.pub
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDGYDO+EKw/2OteUi6IjyWPOoLkTsVhApCDhqA6b4Egpc1sdmwDKaIWz06gdPUncGkCTvKF35gEi+yT3SPdjJE+8/mbD3IVpFW7GUU5MWB3JvqJEI2kr4NBuO876ygxrFUe4sOnZLqIX28qwYeG31XWyYIvd27G7ycTfFFiULa20QeipsEtypKwTj3kw5+xVbqGNl6emSqRKWhvhk1AT4InuLy2Vxdz3ssRxLBUQLTbd/ltpRtv5M2+zJw7rUUfjDsXQrwN+y/N4CXbWS+2eX/OmVBA+jbc9IzHonJQu6DgO0Mr7ALEjAmk/8q4clejOECkbktZILf7R7hVzXu4Pmbf root@centos7-liyj
[root@centos7-liyj ~]#cat .ssh/id_rsa
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

生成的公钥和密钥

2、传送密钥文件至远程机器对应用户的家目录

[root@centos7-liyj ~]#ssh-copy-id -i /root/.ssh/id_rsa.pub root@10.0.0.88
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host '10.0.0.88 (10.0.0.88)' can't be established.
ECDSA key fingerprint is SHA256:znuk6BAInoe362ut3bwJWL5K6tg8VKfXj2EHZ/8mt8s.
ECDSA key fingerprint is MD5:a8:ca:c4:71:1a:11:6b:28:f5:f0:17:b6:a8:f4:49:e4.
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
root@10.0.0.88's password: #输入远程用户的密码

Number of key(s) added: 1

Now try logging into the machine, with: "ssh 'root@10.0.0.88'"
and check to make sure that only the key(s) you wanted were added.

[root@centos8-liyj ~]#ll -a
total 23980
dr-xr-x---. 4 root root 188 Apr 29 13:38 .
dr-xr-xr-x. 19 root root 270 Apr 28 09:45 ..
-rw-------. 1 root root 1470 Apr 18 18:34 anaconda-ks.cfg
-rw-------. 1 root root 9755 Apr 28 19:08 .bash_history
-rw-r--r--. 1 root root 18 May 11 2019 .bash_logout
-rw-r--r--. 1 root root 176 May 11 2019 .bash_profile
-rw-r--r--. 1 root root 176 Apr 18 19:38 .bashrc
drwx------ 4 root root 32 Apr 27 22:09 .config
-rw-r--r--. 1 root root 100 May 11 2019 .cshrc
-rw-r--r-- 1 root root 24504320 Apr 28 10:02 -J
drwx------ 2 root root 29 Apr 29 15:44 .ssh
-rw-r--r--. 1 root root 129 May 11 2019 .tcshrc
-rw------- 1 root root 11607 Apr 28 11:37 .viminfo
[root@centos8-liyj ~]#tree .ssh/
.ssh/
└── authorized_keys

0 directories, 1 file
[root@centos8-liyj ~]#cat .ssh/authorized_keys
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDGYDO+EKw/2OteUi6IjyWPOoLkTsVhApCDhqA6b4Egpc1sdmwDKaIWz06gdPUncGkCTvKF35gEi+yT3SPdjJE+8/mbD3IVpFW7GUU5MWB3JvqJEI2kr4NBuO876ygxrFUe4sOnZLqIX28qwYeG31XWyYIvd27G7ycTfFFiULa20QeipsEtypKwTj3kw5+xVbqGNl6emSqRKWhvhk1AT4InuLy2Vxdz3ssRxLBUQLTbd/ltpRtv5M2+zJw7rUUfjDsXQrwN+y/N4CXbWS+2eX/OmVBA+jbc9IzHonJQu6DgO0Mr7ALEjAmk/8q4clejOECkbktZILf7R7hVzXu4Pmbf root@centos7-liyj

远程的机器

3、远程连接88号机器

[root@centos7-liyj ~]#ssh 10.0.0.88
Last login: Fri Apr 29 13:37:58 2022 from 10.0.0.1
[root@centos8-liyj ~]#

4、对私钥加密

[root@centos7-liyj ~]#ssh-keygen -p
Enter file in which the key is (/root/.ssh/id_rsa): #默认
Enter new passphrase (empty for no passphrase): #密码
Enter same passphrase again: #再次确认密码
Your identification has been saved with the new passphrase.
[root@centos7-liyj ~]#ssh 10.0.0.88
Enter passphrase for key '/root/.ssh/id_rsa': #输入私钥密码
Last login: Fri Apr 29 15:58:51 2022 from 10.0.0.1
[root@centos8-liyj ~]#

5、启动ssh代理，只要不退出 ssh代理进程，基于同一个公钥远程连接机器的就一直免输密码

[root@centos7-liyj ~]#ssh-agent bash #启用代理
[root@centos7-liyj ~]#ps aux |grep agent
root 1247 0.0 0.0 72552 784 ? Ss 16:06 0:00 ssh-agent bash
root 1259 0.0 0.0 112812 980 pts/0 R+ 16:06 0:00 grep --color=auto agent
[root@centos7-liyj ~]#ssh-add #添加代理
Enter passphrase for /root/.ssh/id_rsa: #私钥密码
Identity added: /root/.ssh/id_rsa (/root/.ssh/id_rsa)
[root@centos7-liyj ~]#ssh 10.0.0.88
Last login: Fri Apr 29 16:02:50 2022 from 10.0.0.77

6、退出代理，代理是进程性的，退出进程就不在生效

[root@centos7-liyj ~]#ssh-agent bash
[root@centos7-liyj ~]#ps aux |grep agent
root 1247 0.0 0.0 72552 784 ? Ss 16:06 0:00 ssh-agent bash
root 1259 0.0 0.0 112812 980 pts/0 R+ 16:06 0:00 grep --color=auto agent
[root@centos7-liyj ~]#ssh-add
Enter passphrase for /root/.ssh/id_rsa:
Identity added: /root/.ssh/id_rsa (/root/.ssh/id_rsa)
[root@centos7-liyj ~]#ssh 10.0.0.88
Last login: Fri Apr 29 16:02:50 2022 from 10.0.0.77
[root@centos8-liyj ~]#exit
logout
Connection to 10.0.0.88 closed.
[root@centos7-liyj ~]#exit
exit
[root@centos7-liyj ~]#ps aux |grep agent
root 1264 0.0 0.0 112812 976 pts/0 S+ 16:10 0:00 grep --color=auto agent
[root@centos7-liyj ~]#

再次连接需输入 私钥密码

范例：基于key验证实现批量主机管理

[root@centos7 ~]#cat hosts.txt
10.0.0.78
10.0.0.10
[root@centos7 ~]#for i in `cat hosts.txt`;do ssh $i hostname -I ;done
10.0.0.78
10.0.0.10