Ubuntu 14.04 LTS下設定SSH免密碼登入

Ubuntu 14.04 LTS下設定SSH免密碼登入

首先用apt-get命令安裝SSH

linuxidc@ubuntu:~$ sudo apt-get install ssh
[sudo] password for linuxidc:
Reading package lists... Done
Building dependency tree     
Reading state information... Done
The following extra packages will be installed:
  libck-connector0 ncurses-term openssh-server openssh-sftp-server
  ssh-import-id
Suggested packages:
  rssh molly-guard monkeysphere
The following NEW packages will be installed:
  libck-connector0 ncurses-term openssh-server openssh-sftp-server ssh
  ssh-import-id
0 upgraded, 6 newly installed, 0 to remove and 6 not upgraded.
Need to get 617 kB of archives.
After this operation, 3,450 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://us.archive.ubuntu.com/ubuntu/ trusty/main libck-connector0 amd64 0.4.5-3.1ubuntu2 [10.5 kB]
Get:2 http://us.archive.ubuntu.com/ubuntu/ trusty/main ncurses-term all 5.9+20140118-1ubuntu1 [243 kB]
Get:3 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main openssh-sftp-server amd64 1:6.6p1-2ubuntu2.3 [34.1 kB]

查詢下使用者目錄下有沒有.ssh資料夾。這個資料夾本身是個隱藏資料夾。安裝SSH的時候應該預設會在安裝使用者的個人目錄下建立改檔案，如果沒有就自己手動建立一個。至於它是用來幹嘛的？SSH使用的是公鑰加密。這個資料夾就是用來存放公鑰和私鑰兩個檔案的資料夾。

linuxidc@ubuntu:~$ ls -a -d .ssh ~
ls: cannot access .ssh: No such file or directory
/home/linuxidc
jerry@ubuntu:~$ mkdir ~/.ssh
linuxidc@ubuntu:~$ ls -a -d .ssh ~
/home/linuxidc  .ssh
jerry@ubuntu:~$

接下來就是生成金鑰了。這裡用ssh_keygen命令生成金鑰。-t表示加密型別，ssh支援rsa（目前流行的公鑰加密演算法）/dsa（digital signature algorithm數位簽章演算法）。-f表示公鑰和私鑰檔案儲存的路徑。可以看到.ssh資料夾下生成了id_dsa（私鑰）和id_dsa.pub（公鑰）兩個檔案。

linuxidc@ubuntu:~$ ssh-keygen -t dsa -P '' -f ~/.ssh/id_dsa
Generating public/private dsa key pair.
Your identification has been saved in /home/linuxidc/.ssh/id_dsa.
Your public key has been saved in /home/linuxidc/.ssh/id_dsa.pub.
The key fingerprint is:
e8:57:37:7d:ae:85:55:33:90:2f:86:80:5d:b0:b3:31 linuxidc@ubuntu
The key's randomart image is:
+--[ DSA 1024]----+
|        o.o. ..  |
|      . o.  ..  |
|        E. . .o.|
|      .  =. + .+|
|      . S.. + o o|
|    .  . . . = |
|      . .    . o|
|      .      o |
|              .  |
+-----------------+

 linuxidc@ubuntu:~$ ls -a ~/.ssh/
 . .. id_dsa id_dsa.pub
 linuxidc@ubuntu:~$
 

新增公鑰到認證的公鑰證書列表中

linuxidc@ubuntu:~$ cat ~/.ssh/id_dsa.pub >> ~/.ssh/authorized_keys
linuxidc@ubuntu:~$

嘗試用SSH連線本地伺服器

linuxidc@ubuntu:~$ ssh localhost
The authenticity of host 'localhost (127.0.0.1)' can't be established.
ECDSA key fingerprint is da:b7:c3:2a:ea:a2:76:4c:c3:c1:68:ca:0e:c2:ea:92.
Are you sure you want to continue connecting (yes/no)? y
Please type 'yes' or 'no': yes
Warning: Permanently added 'localhost' (ECDSA) to the list of known hosts.
Welcome to Ubuntu 14.04.3 LTS (GNU/Linux 3.19.0-39-generic x86_64)

 * Documentation:  https://help.ubuntu.com/

The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

linuxidc@ubuntu:~$

下面關於SSH相關的文章您也可能喜歡，不妨參考下：

Ubuntu 下設定 SSH服務全過程及問題解決 http://www.linuxidc.com/Linux/2011-09/42775.htm

Ubuntu 14.04 下安裝Samba 及SSH 伺服器端的方法 http://www.linuxidc.com/Linux/2015-01/111971.htm

SSH服務遠端存取Linux伺服器登陸慢 http://www.linuxidc.com/Linux/2011-08/39742.htm

提高Ubuntu的SSH登陸認證速度的辦法 http://www.linuxidc.com/Linux/2014-09/106810.htm

開啟SSH服務讓Android手機遠端存取 Ubuntu 14.04  http://www.linuxidc.com/Linux/2014-09/106809.htm

如何為Linux系統中的SSH新增雙重認證 http://www.linuxidc.com/Linux/2014-08/105998.htm

在 Linux 中為非 SSH 使用者設定 SFTP 環境 http://www.linuxidc.com/Linux/2014-08/105865.htm

Linux 上SSH 服務的設定和管理 http://www.linuxidc.com/Linux/2014-06/103627.htm

本文永久更新連結地址：http://www.linuxidc.com/Linux/2016-09/135404.htm