一.错误问题 

[root@RedHat-5 pam.d]# tail /var/log/secure
Sep 12 11:39:48 RedHat-5 vsftpd: PAM adding faulty module: /lib/security/pam_mysql.so
Sep 12 11:42:39 RedHat-5 vsftpd: PAM unable to dlopen(/lib/security/pam_mysql.so)
Sep 12 11:42:39 RedHat-5 vsftpd: PAM [error: /lib/security/pam_mysql.so: cannot open shared object file: No such file or directory]
Sep 12 11:42:39 RedHat-5 vsftpd: PAM adding faulty module: /lib/security/pam_mysql.so
Sep 12 11:42:59 RedHat-5 vsftpd: PAM unable to dlopen(/lib/security/pam_mysql.so)
Sep 12 11:42:59 RedHat-5 vsftpd: PAM [error: /lib/security/pam_mysql.so: cannot open shared object file: No such file or directory]
Sep 12 11:42:59 RedHat-5 vsftpd: PAM adding faulty module: /lib/security/pam_mysql.so
Sep 12 11:44:30 RedHat-5 vsftpd: PAM unable to dlopen(/lib/security/pam_mysql.so)
Sep 12 11:44:30 RedHat-5 vsftpd: PAM [error: /lib/security/pam_mysql.so: cannot open shared object file: No such file or directory]
Sep 12 11:44:30 RedHat-5 vsftpd: PAM adding faulty module: /lib/security/pam_mysql.so

二.解决方法

  经过仔细查看前面的步骤，发现原来make install的时候默认安装在/usr/local/lib下。修改/etc/pam.d/vsftpd.mysql文件

auth required /usr/lib/security/pam_mysql.so user=vsftpd passwd=www.luochen.com host=localhost db=vsftpd table=users usercolumn=name passwdcolumn=password crypt=0

account required /usr/lib/security/pam_mysql.so user=vsftpd passwd=www.luochen.com host=localhost db=vsftpd table=users usercolumn=name passwdcolumn=password crypt=0

  在登录，成功！换用其他加密方式，也都可以。然后试验pam_mysql v0.7新加的config_file配置选项。这个选项用来指定一个配置文件，可以把所有pam_mysql的配置放在这个文件中。这样的话，/etc/pam.d/vsftpd.mysql的内容变成这样:

auth required /usr/lib/security/pam_mysql.so config_file=/etc/security/pam_mysql.conf
account required /usr/lib/security/pam_mysql.so config_file=/etc/security/pam_mysql.conf

  /etc/security/pam_mysql.conf的内容:
     users.host=localhost

     users.database=vsftpd
     users.db_user=root
     users.db_passwd=redhat
     users.table=users
     users.user_column=name
     users.password_column=password
     users.password_crypt=3
     verbose=1
     log.enabled=1
     log.table=logs
     log.message_column=msg
     log.pid_column=pid
     log.user_column=user
     log.host_column=host
     log.rhost_column=rhost
     log.time_column=logtime