SSH 免秘钥登录

  1.什么是SSH

• SSH(远程连接工具)连接原理：ssh服务是一个守护进程(demon)，系统后台监听客户端的连接，ssh服务端的进程名为sshd,负责实时监听客户端的请求(IP 22端口)，包括公共秘钥等交换等信息。
• ssh服务端由2部分组成： openssh(提供ssh服务)    openssl(提供加密的程序)
• ssh的客户端可以用 XSHELL，Securecrt, Mobaxterm等工具进行连接

 2.免秘钥登录远程服务器

客户端IP:192.168.139.136      服务端IP：192.168.139.135

 2.1.首先我们在客户端生成一个公钥和一个私钥

•  [root@localhost ~]# ssh-keygen -t dsa
•  Generating public/private dsa key pair.
• Enter file in which to save the key (/root/.ssh/id_dsa): 
•  Enter passphrase (empty for no passphrase): 
•   Enter same passphrase again: 
•  Your identification has been saved in /root/.ssh/id_dsa.
•  Your public key has been saved in /root/.ssh/id_dsa.pub.
•   The key fingerprint is:
•  SHA256:uIywlzFlO4k3uo/OgpSKHvX+HWP/KKQtkl9ufwynJsk [email protected]
•  The key's randomart image is:
•  +---[DSA 1024]----+
•  |                 |
•  |                 |
•  |      o          |
• |     + +         |
• |  o.+ B S        |
• | o.o.O + . . .   |
• |+o. =.+ ==. =    |
• |+ oo.= o=E+o.o   |
• |.. o=o=ooo=+o.   |
• +----[SHA256]-----+

2.2.我们将公钥拷贝到服务端

• 利用远程机的用户登录
• ssh-copy-id -i id_dsa.pub [email protected]
• [root@localhost .ssh]# ssh-copy-id -i id_dsa.pub [email protected]
• /usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "id_dsa.pub"
• /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. 

2.3.远程连接服务端

• [root@localhost .ssh]# ssh [email protected]
• Last failed login: Thu May 23 16:18:25 CST 2019 from 192.168.139.136 on ssh:notty
• There were 2 failed login attempts since the last successful login.
• Last login: Thu May 23 16:14:24 2019 from knight-pc.airdream
• [root@localhost ~]# ls
•  anaconda-ks.cfg
•  [root@localhost ~]# cd /
•  [root@localhost /]# ls
•  bin  boot  data  dev  etc  home  lib  lib64  media  mnt  opt  proc  root  run  sbin  srv  swap  sys  tmp  usr  var  web
•   [root@localhost /]# cd home
•   [root@localhost home]# ls
•    git
•   [root@localhost home]# exit
•    logout
•  Connection to 192.168.139.135 closed

3. 总结一下钥匙和锁的关系

  3.1.多个钥匙开一把锁

      把id_dsa.pub 复制给各个服务器

   3.2.一个钥匙开duobasuo

              把id_dsa 传给各个服务器

              把id_dsa 传给自己