ssh-copy-id

1. 上一節免密碼設定的複雜過程，linux 上已幫你寫好一支腳本 ssh-copy-id，先執行 ssh-keygen 產生 ssh key。

   [root@kvm3 ~]# 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:
   01:be:06:3d:89:bd:5b:b4:7a:e6:37:b0:07:44:86:35 root@kvm3.deyu.wang
   The key's randomart image is:
   +--[ RSA 2048]----+
   |      .oE        |
   |     =.oo.       |
   |    o *oo        |
   |     . =.o       |
   |      +.S        |
   |     . +o        |
   |      o o+       |
   |       +. +      |
   |        .o .     |
   +-----------------+
   

2. 執行 ssh-copy-id 參數為要登入的主機，就可以將 public key 傳送到該主機，並幫忙設定好免密碼登入的信任主機。

   [root@kvm3 ~]# ssh-copy-id 192.168.122.7
   The authenticity of host '192.168.122.7 (192.168.122.7)' can't be established.
   ECDSA key fingerprint is 30:b2:6e:89:45:69:cc:2f:52:a2:c7:d0:dc:2b:aa:e9.
   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@192.168.122.7's password: 
   
   Number of key(s) added: 1
   
   Now try logging into the machine, with:   "ssh '192.168.122.7'"
   and check to make sure that only the key(s) you wanted were added.
   

3. 登入 192.168.122.7 已不需要輸入密碼。

   [root@kvm3 ~]# ssh 192.168.122.7
   Last login: Thu Feb 15 11:58:57 2018 from deyu.wang
   [root@kvm7 ~]#