winbind
These examples may only work on Samba 3. See info about Winbindd here: https://wiki.samba.org/index.php/Configuring_Winbindd_on_a_Samba_AD_DC
Examples
Ping the winbind servers
wbinfo -p
list the domain users
wbinfo -u
try authenticating the user against winbind
wbinfo -a dhoherd