制作ssh rpm 包升级后，ssh无法登录系统，报错如下：
PAM unable to dlopen(/lib64/security/pam_stack.so): /lib64/security/pam_stack.so: cannot open shared object file: No such file or directory PAM adding faulty module: /lib64/security/pam_stack.so
经过排查发现是ssh rpm 升级后会修改/etc/pam.d/sshd 文件
#%PAM-1.0 auth required pam_stack.so service=system-auth account required pam_nologin.so account required pam_stack.so service=system-auth password required pam_stack.so service=system-auth session required pam_stack.so service=system-auth
需要恢复原来的模样，如下：
#%PAM-1.0 auth required pam_sepermit.so auth include password-auth account required pam_nologin.so account include password-auth password include password-auth # pam_selinux.so close should be the first session rule session required pam_selinux.so close session required pam_loginuid.so # pam_selinux.so open should only be followed by sessions to be executed in the user context session required pam_selinux.so open env_params session optional pam_keyinit.so force revoke session include password-auth
原文：http://my.oschina.net/u/142602/blog/313756