After you integrate a NAS into your domain you will get permission errors when trying to mount the SMB share using CIFS.

 

Solution

You have to use add the domain parameter from now on:

If the user is a domainuser: mount -t cifs -o username=USERNAME,password=PASSWORD,domain=DOMAIN //10.10.10.10/path/ /mnt/MOUNTPOINT

If the user is local on the nas: mount -t cifs -o username=USERNAME,password=PASSWORD,domain=. //10.10.10.10/path/ /mnt/MOUNTPOINT

Cheers, Ori