@[TOCUbuntu实现免密登录)
准备环境：两台Ubuntu节点server版，，ip我设置的静态，可以实现ssh远程登录window终端（cmd），也可以实现远程登录的,需要注意的是使用Ubuntu远程登录需要先登录普通用户再切换到root用户

说明：登录完毕后切换到root后，root是没有设置密码的，需要使用passwd设置一下root的密码

1，修改一下ssh配置文件
用于开启远程操作的密码验证

root@master:~# vi /etc/ssh/sshd_config

# Logging
#SyslogFacility AUTH
#LogLevel INFO

# Authentication:

#LoginGraceTime 2m
#PermitRootLogin prohibit-password
PermitRootLogin yes       #需要开启的是这行，注意把注释去掉
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

#PubkeyAuthentication yes

2，使用windows终端实现远程登录

C:\Users\huhy>ssh huhy@192.168.200.100
huhy@192.168.200.100's password:
Welcome to Ubuntu 22.04 LTS (GNU/Linux 5.15.0-25-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Thu Sep  1 03:46:07 PM UTC 2022

  System load:  0.08251953125      Processes:              221
  Usage of /:   33.3% of 19.51GB   Users logged in:        1
  Memory usage: 10%                IPv4 address for ens33: 192.168.200.100
  Swap usage:   0%


0 updates can be applied immediately.


Last login: Thu Sep  1 15:34:51 2022 from 192.168.200.1
huhy@master:~$ sudo su root

3，做个域名解析

root@master:~# vi /etc/hosts

127.0.0.1 localhost
127.0.1.1 huhy

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
192.168.200.100 master
192.168.200.101 slave1         # 添加最后两行即可，注意更改IP

# 测试

root@master:~# ping master
PING master (192.168.200.100) 56(84) bytes of data.
64 bytes from master (192.168.200.100): icmp_seq=1 ttl=64 time=0.023 ms
64 bytes from master (192.168.200.100): icmp_seq=2 ttl=64 time=0.050 ms
64 bytes from master (192.168.200.100): icmp_seq=3 ttl=64 time=0.106 ms
^C
--- master ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2034ms
rtt min/avg/max/mdev = 0.023/0.059/0.106/0.034 ms
root@master:~# ping slave1
PING slave1 (192.168.200.101) 56(84) bytes of data.
64 bytes from slave1 (192.168.200.101): icmp_seq=1 ttl=64 time=0.773 ms
64 bytes from slave1 (192.168.200.101): icmp_seq=2 ttl=64 time=0.830 ms
64 bytes from slave1 (192.168.200.101): icmp_seq=3 ttl=64 time=0.820 ms
^C
--- slave1 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2006ms
rtt min/avg/max/mdev = 0.773/0.807/0.830/0.024 ms
root@master:~#

#alave1同样操作

root@slave1:~# vi /etc/hosts
root@slave1:~# ping master -c3
PING master (192.168.200.100) 56(84) bytes of data.
64 bytes from master (192.168.200.100): icmp_seq=1 ttl=64 time=0.640 ms
64 bytes from master (192.168.200.100): icmp_seq=2 ttl=64 time=1.95 ms
64 bytes from master (192.168.200.100): icmp_seq=3 ttl=64 time=2.20 ms

--- master ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2020ms
rtt min/avg/max/mdev = 0.640/1.598/2.202/0.685 ms
root@slave1:~# ping slave1 -c3
PING slave1 (192.168.200.101) 56(84) bytes of data.
64 bytes from slave1 (192.168.200.101): icmp_seq=1 ttl=64 time=0.023 ms
64 bytes from slave1 (192.168.200.101): icmp_seq=2 ttl=64 time=0.067 ms
64 bytes from slave1 (192.168.200.101): icmp_seq=3 ttl=64 time=0.073 ms

--- slave1 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2057ms
rtt min/avg/max/mdev = 0.023/0.054/0.073/0.022 ms
root@slave1:~#

4，做免密操作

ssh: Could not resolve hostname key-gen: Temporary failure in name resolution
root@master:~# ssh-keygen
Generating public/private rsa key pair.             # 连续回车四下
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:X2aQjgO4k5zdxe5kjsvpqILy9C6gkWEBjpKp77Q1AxY root@master
The key's randomart image is:
+---[RSA 3072]----+
|o                |
|o+   .   . .     |
|=.E . .   =      |
|+. o = o = .     |
|ooo * . S = +    |
|+o . .   O +     |
|.++ +   . +      |
|++o+ o o o       |
|..+++...=        |
+----[SHA256]-----+
root@master:~#

# slave1同样操作

root@slave1:~# 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:WASg8Kr3Fs/7L7CyB+SXW6K3dm4hmuVMaYXCmeFTYIc root@slave1
The key's randomart image is:
+---[RSA 3072]----+
|.   ++o..        |
| o oE...         |
|  oo = ..        |
| .  O .o.        |
|.  o o.+S        |
|.   + @ o        |
|. .  / B .       |
| . .* @ +        |
|   .o*oBoo.      |
+----[SHA256]-----+
root@slave1:~#

#ssh传输公钥

root@master:~# ssh-copy-id -i /root/.ssh/id_rsa.pub root@slave1
root@slave1:~# ssh-copy-id -i /root/.ssh/id_rsa.pub root@master
#传输后输入密码即可

#测试master
root@master:~# ssh slave1
Welcome to Ubuntu 22.04 LTS (GNU/Linux 5.15.0-25-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Thu Sep  1 04:21:53 PM UTC 2022

  System load:  0.0498046875       Processes:              217
  Usage of /:   34.4% of 19.51GB   Users logged in:        1
  Memory usage: 10%                IPv4 address for ens33: 192.168.200.101
  Swap usage:   0%


0 updates can be applied immediately.


Last login: Thu Sep  1 16:18:54 2022 from 192.168.200.100
root@slave1:~#

#测试slave1
root@slave1:~# ssh master
Welcome to Ubuntu 22.04 LTS (GNU/Linux 5.15.0-25-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Thu Sep  1 04:22:46 PM UTC 2022

  System load:  0.0107421875       Processes:              216
  Usage of /:   33.3% of 19.51GB   Users logged in:        1
  Memory usage: 10%                IPv4 address for ens33: 192.168.200.100
  Swap usage:   0%


0 updates can be applied immediately.


Last login: Thu Sep  1 16:18:46 2022 from 192.168.200.101
root@master:~#