一、情景
把主機之間都能遠程ssh免密碼登陸。
二、原理
很簡單，使用ssh-keygen 在主機a上生成private和public密鑰，將生成的public密鑰拷貝到遠程機器主機b上后,就可以使用ssh命令無需密碼登錄到另外一臺機器主機b上。
三、步驟
主機a：
1、 生成公鑰和私鑰文件id_rsa和id_rsa.pub （敲3下回車即可）
[root@bogon ~]# ssh-keygen -t rsa
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:
67:da:0d:79:e0:d6:2b:cd:7d:22:af:51:7e:9c:75:fe root@bogon
the key’s randomart image is:
+–[ rsa 2048]—-+
| |
| |
| . |
| . + |
| s b o . o|
| * * = o+|
| . o b +.=|
| . + +.|
| … e|
+—————–+
2、ssh-cop-id命令會將指定的公鑰文件復制到遠程計算機
[root@bogon ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@10.1.250.166
the authenticity of host ‘10.1.250.166 (10.1.250.166)’ can’t be established.
rsa key fingerprint is c8:9d:6d:92:55:77:3d:3e:af:f5:cb:18:80:5a:47:93.
are you sure you want to continue connecting (yes/no)? yes
warning: permanently added ‘10.1.250.166’ (rsa) to the list of known hosts.
reverse mapping checking getaddrinfo for bogon [10.1.250.166] failed – possible break-in attempt!
root@10.1.250.166’s password:
now try logging into the machine, with “ssh ‘root@10.1.250.166′”, and check in:
.ssh/authorized_keys
to make sure we haven’t added extra keys that you weren’t expecting.
3、然后ssh登陸主機b驗證是否需要密碼
[root@localhost ~]# ssh 10.1.250.166
reverse mapping checking getaddrinfo for bogon [10.1.250.166] failed – possible break-in attempt!
last login: wed oct 21 10:05:39 2015 from 10.1.250.141
[root@bogon ~]#
4、登陸成功后，我們需要在主機b也做下以上3步，這樣就可以相互免密碼ssh登陸。（如果有多臺主機，每臺主機都做下相同操作，以方便以后管理）。
5、權限問題
建議用其他用戶做ssh登陸的話，調整目錄文件權限
設置authorized_keys權限
chmod 644 authorized_keys
設置.ssh目錄權限
chmod 700 -r .ssh
6、要保證.ssh和authorized_keys都只有用戶自己有寫權限。否則驗證無效。
