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:
The key's randomart image is:
+--[ RSA 2048]----+
| .oE |
| =.oo. |
| o *oo |
| . =.o |
| +.S |
| . +o |
| o o+ |
| +. + |
| .o . |
- 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
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.
- 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