pam 验证文章连接

http://liuyuanljy.blog.51cto.com/607434/163369/    用PAM来验证linux安全

http://www.2cto.com/os/201409/337029.html     关于linux的密码策略

http://blog.chinaunix.net/uid-291705-id-2134362.html  PAM配置 

http://blog.csdn.net/zhgn2/article/details/7531429   pam应用举例