ssh配置pam登陆策略
1.pam下sshd配置文件问题
升级后openssh中的配置文件可能会导致root用户和普通用户输入正确密码也无法登陆
解决办法：
使用原sshd配置文件
#%PAM-1.0
auth required pam_sepermit.so
auth substack password-auth
auth include postlogin
# Used with polkit to reauthorize users in remote sessions
-auth optional pam_reauthorize.so prepare
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 required pam_namespace.so
session optional pam_keyinit.so force revoke
session include password-auth
session include postlogin
# Used with polkit to reauthorize users in remote sessions
-session optional pam_reauthorize.so prepare
2.（排查问题笔记）系统日志
tail -f /var/log/messages
/var/log/messages 存放的是系统的日志信息，它记录了各种事件，基本上什么应用都能往里写日志，在做故障诊断时可以首先查看该文件内容