ssky-keygen + ssh-copy-id 無密碼登錄遠程LINUX主機

ssh-keygen  產生公鑰與私鑰對.

ssh-copy-id 將本機的公鑰複製到遠程機器的authorized_keys文件中，ssh-copy-id也能讓你有到遠程機器的home, ~./ssh , 和 ~/.ssh/authorized_keys的權利

ssh-add (有可能需加此命令）

使用下例中ssky-keygen和ssh-copy-id，僅需經過3個步驟的簡單設置而無需輸入密碼就能登陸遠程Linux主機。 
ssh-keygen 建立公鑰和密鑰。 
ssh-copy-id 把本地主機的公鑰複製到遠程主機的authorized_keys文件上。
ssh-copy-id 也會給遠程主機的用戶主目錄（home）和~/.ssh, 和~/.ssh/authorized_keys設置合適的權限 。

步驟1: 用 ssh-key-gen 在本地主機上建立公鑰和密鑰
ligh@local-host$ ssh-keygen -t  rsa
Enter file in which to save the key (/home/jsmith/.ssh/id_rsa):[Enter key] 
Enter passphrase (empty for no passphrase): [Press enter key]
Enter same passphrase again: [Pess enter key]
Your identification has been saved in /home/jsmith/.ssh/id_rsa.
Your public key has been saved in /home/jsmith/.ssh/id_rsa.pub. 
The key fingerprint is: 33:b3:fe:af:95:95:18:11:31:d5:de:96:2f:f2:35:f9 
ligh@local-host

步驟2: 用 ssh-copy-id 把公鑰複製到遠程主機上
ligh@local-host$ ssh-copy-id -i ~/.ssh/id_rsa.pub  root@192.168.0.3
ligh@remote-host‘s password:
Now try logging into the machine, with ―ssh ?remote-host‘‖, and check in: 
.ssh/authorized_keys to make sure we haven‘t added extra keys that you weren‘t expecting.
[注: ssh-copy-id 把密鑰追加到遠程主機的 .ssh/authorized_key 上.]

步驟3: 直接登陸遠程主機
ligh@local-host$ ssh remote-host 
Last login: Sun Nov 16 17:22:33 2008 from 192.168.1.2 
[注: SSH 不會詢問密碼.] 
ligh@remote-host$ 
[注: 你如今已經登陸到了遠程主機上]

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