解决ssh-keygen需要密码问题

折腾了一个晚上的问题，没解决，网上很多人提问，但没找到正确的解决方法。
今天早上继续，终于解决！
按如下配置：
[oracle@dbrac3 opt]$ mkdir ~/.ssh
[oracle@dbrac3 opt]$ chmod 700 ~/.ssh
[oracle@dbrac3 opt]$ ssh-keygen -t rsa
[oracle@dbrac3 opt]$ ssh-keygen -t dsa
[oracle@dbrac3 opt]$ cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
[oracle@dbrac3 opt]$ cat ~/.ssh/id_dsa.pub >> ~/.ssh/authorized_keys
[oracle@dbrac3 opt]$ ssh dbrac3 date
oracle@dbrac3's password:
Wed Jul 16 02:25:23 CST 2008

同样的步骤，在另外几台机器上都是正常的，无须提示输入密码。很奇怪，而且，是从同一个vm模板上clone出来的机器，为什么有的可以，有的不可以，很头痛，尝试不同的组合都不行。
用ssh的调试模式：
[oracle@dbrac3 .ssh]$ ssh -v dbrac3 date
...
debug1: Unspecified GSS failure. Minor code may provide more information
Unknown code krb5 195
debug1: Unspecified GSS failure. Minor code may provide more information
Unknown code krb5 195
debug1: Unspecified GSS failure. Minor code may provide more information
Unknown code krb5 195
debug1: Next authentication method: publickey
debug1: Trying private key: /opt/oracle/.ssh/identity
debug1: Offering public key: /opt/oracle/.ssh/id_rsa
debug1: Authentications that can continue: publickey,gssapi-with-mic,password
debug1: Offering public key: /opt/oracle/.ssh/id_dsa
debug1: Authentications that can continue: publickey,gssapi-with-mic,password
debug1: Next authentication method: password
oracle@dbrac3's password:
debug1: Authentication succeeded (password).
...
而在另外一台正常的机器，相关的步骤如下：
[oracle@dbrac1 ~]$ ssh -v dbrac1 date
...
debug1: Unspecified GSS failure. Minor code may provide more information
Unknown code krb5 195
debug1: Unspecified GSS failure. Minor code may provide more information
Unknown code krb5 195
debug1: Unspecified GSS failure. Minor code may provide more information
Unknown code krb5 195
debug1: Next authentication method: publickey
debug1: Trying private key: /opt/oracle/.ssh/identity
debug1: Offering public key: /opt/oracle/.ssh/id_rsa
debug1: Server accepts key: pkalg ssh-rsa blen 277
debug1: read PEM private key done: type RSA
debug1: Authentication succeeded (publickey).
...
从对比中看不出问题所在。

检查系统的安全日志：
[root@dbrac3 ~]# vi /var/log/secure
Jul 16 02:25:23 dbrac3 sshd[5974]: pam_unix(sshd:session): session opened for user oracle by (uid=0)
Jul 16 02:25:23 dbrac3 sshd[5974]: pam_unix(sshd:session): session closed for user oracle
[root@dbrac3 ~]# tail -f /var/log/secure
Jul 16 02:25:17 dbrac3 sshd[5947]: Authentication refused: bad ownership or modes for directory /opt/oracle
Jul 16 02:25:17 dbrac3 sshd[5947]: Authentication refused: bad ownership or modes for directory /opt/oracle

提示用户home目录有问题，继续检查：
[oracle@dbrac3 opt]$ ll
total 316
drwxrwxr-x 20 oracle dba 4096 Jul 16 02:13 oracle

而正常的机器：
[oracle@dbrac1 opt]$ ll
total 324
drwxr-xr-x 8 oracle dba 4096 Jul 12 07:46 oracle

权限不同，虽然觉得好像没什么相关性，但测试修改看看
[oracle@dbrac3 opt]$ chmod 755 /opt/oracle
[oracle@dbrac3 opt]$ ll
total 316
drwxr-xr-x 20 oracle dba 4096 Jul 16 02:13 oracle

再次执行：
[oracle@dbrac3 opt]$ ssh dbrac3 date
Wed Jul 16 02:28:53 CST 2008

顺利的通过，原来是目录的授权出了问题，但以前这类问题，是授权不够才发生，现在授权多了，也不行，有点和经验相悖！

=========================================================================
ssh-keygen -t rsa
cd ~/.ssh
cat id_rsa.pub >> authorized_keys
ssh hdp2 cat ~/.ssh/authorized_keys >> ./authorized_keys
scp authorized_keys hdp2:~/.ssh/authorized_keys
ssh hdp1 date
ssh hdp2 date
转载自以下链接： http://blog.sina.com.cn/s/blog_538285a70100nvz6.html