系統是Centos7，在登陸界面，輸入完用戶名敲回車后，沒有提示我輸入密碼，就直接報“Login incorrect”了：
CentOS Linux 7 (core) Kernel 3.10.0-327.eel7.x86_64 on an x86_64 localhost login：root Login incorrect Login incorrect Login incorrect
此問題是由於系統的某些更新引起pam.d/login的變化。我把上面/etc/pam.d/login中的兩個postlogin以及pam_loginuid.so一行注釋掉就OK了，暫時不知道這兩個模塊的驗證策略如何。
[root@localhost ~]# cat /etc/pam.d/login
#%PAM-1.0 auth [user_unknown=ignore success=ok ignore=ignore default=bad] pam_securetty.so auth substack system-auth # auth include postlogin account required pam_nologin.so account include system-auth password include system-auth # pam_selinux.so close should be the first session rule session required pam_selinux.so close # session required pam_loginuid.so session optional pam_console.so # pam_selinux.so open should only be followed by sessions to be executed in the user context session required pam_selinux.so open session required pam_namespace.so session optional pam_keyinit.so force revoke session include system-auth # session include postlogin -session optional pam_ck_connector.so