[root@centos7 ~]# vi /etc/pam.d/vftpusers
[root@centos7 ~]# cat /etc/pam.d/vftpusers
#%PAM-1.0
auth    required        pam_userdb.so   db=/etc/vsftpd/vftpusers
account required        pam_userdb.so   db=/etc/vsftpd/vftpusers
session required        pam_loginuid.so