vsftpd authentication with active directory

[solazzzw]

I'm trying to authenticate vsftpd from my active directory.
vsftpd:3.0.2,centos 7, ad:server 2012 r2
my /etc/pam.d/vsftpd file is like this:
#%PAM-1.0
session optional pam_keyinit.so force revoke
auth sufficient pam_ldap.so #keep this as the first 'auth' item
account sufficient pam_ldap.so #keep this as the first 'account' item
auth required pam_listfile.so item=user sense=deny file=/etc/vsftpd/ftpusers onerr=succeed
auth required pam_shells.so
auth include password-auth
account include password-auth
session required pam_loginuid.so
session include password-auth

but I don't know how to specify my dc's IP address. I cannot find the pam_ldap.so file.