ssh 免密登录

1. [root@localhost .ssh]# /usr/bin/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:

   30:f6:d7:2a:ac:56:eb:3f:fa:40:25:8d:90:96:68:cb 

   root@localhost.localdomain

   在主机/.ssh目录下生成密匙

   使用ssh的rsa密匙

   其中

   id_rsa 私匙

   id_rsa.pub 公匙

   下述命令产生不同类型的密钥

   ssh-keygen -t dsa 

   ssh-keygen -t rsa 

   ssh-keygen -t rsa1 

2. [root@localhost .ssh]# scp /root/.ssh/id_rsa.pubroot@172.16.142.5:/root/.ssh/authorized_keys

   The authenticity of host '172.16.142.5 (172.16.142.5)' can't be established.

   RSA key fingerprint is 4b:a5:74:fb:2e:08:60:af:fa:76:d4:b0:26:4c:13:75.

   Are you sure you want to continue connecting (yes/no)? yes

   Warning: Permanently added '172.16.142.5' (RSA) to the list of known hosts.

   root@172.16.142.5's password:

   id_rsa.pub                                                                                        100% 236     0.2KB/s   00:00 

   说明：

   将公钥拷贝到远端主机，并写入授权列表文件

   你也可以把公钥文件拷贝过去后，在远端主机下直接执行

   touch /root/.ssh/authorized_keys

   cat /root/.ssh/id_rsa.pub >> /root/.ssh/authorized_keys

3. 操作完毕，登陆检查。   

   [root@localhost .ssh]# ssh 172.16.142.5

   root@172.16.142.5's password:

   请注意此时如果仍提示输入密码，请检查如下文件夹和文件的操作权限，这是非常重要的， 否则ssh公钥认证体制不能正常工作：

   172.16.142.4（客户端）

   /home/root文件夹的权限是600

   /home/root/.ssh文件夹的权限是600 （好像这个权限关系不是很大）

   /home/root/.ssh/id_dsa私钥的权限600

   172.16.142.5（远端主机）

   /home/root文件夹的权限是644

   /home/root/.ssh文件夹的权限是644 （好像这个权限关系不是很大）

   /root/.ssh/authorized_keys公钥的权限644

4. 4

   [root@localhost ~]# ssh 172.16.142.5

   Last login: Sat Dec 15 21:10:17 2007 from 172.16.142.4

   [root@localhost ~]# 

   无密码SSH登陆成功！