思路就是：在本地主機上生成 公鑰，私鑰，然後將公鑰放到遠程主機的.ssh/authrized_keys 裡面使用下例中ssky-keygen和ssh-copy-id，僅需通過3個步驟的簡單設置而無需輸入密碼就能登錄遠程Linux主機。
ssh-keygen 創建公鑰和密鑰。
ssh-copy-id 把本地主機的公鑰復制到遠程主機的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 在本地主機上創建公鑰和密鑰
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 把公鑰復制到遠程主機上
ligh@local-host$ ssh-copy-id -i ~/.ssh/id_rsa.pub [email protected]
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: 直接登錄遠程主機
ligh@local-host$ ssh 192.168.0.3
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: 你現在已經登錄到了遠程主機上]