If the CIFS utility is asking you for a Username and Password every time you attempt to mount -a (mount a NAS in Ubuntu) then make sure that you haven't included a period (.) thinking that it is a comma (,).
+1 888-688-2939 
If you want to mount another disk space in Linux Ubuntu follows instructions below:
1. cd etc/
2. sudo apt-get install cifs-utils
2. sudo nano fstab
3. Under "/swap.img" type the following:
//IPAddressOfYourDisk/FolderName /FolderYouWantToBindTheDiskTo cifs guest,uid=100,iocharset=utf8 0 0 #There is a comma next to "guest"
- guest should be replaced with user credentials to log into the Disk Space.
4. sudo mount -a #To finally mount the settings pasted in fstab or sudo mount -av #To see more information about the mount[NB] If you have followed the code above and you get the error that says "mount: /etc/fstab: parse error at line 6 -- ignored"
Solution: Remove the spaces between guest,uid=100,inocharset=utf8 0 0
I got an error saying "mount error(112): Host is down" Any idea why? I pinged the host is responding.
@Mark make sure you do: sudo apt-get install cifs-utils
I got an error saying bad option; for several filesystem (e.g. nfs, cifs) you might need a /sbin/mount
Mark said:
Jack, the error that says that "The Host is down" is due to your Network Attached Devices nor supporting SMB 3.0, it shows that the protocol is different from what the CIFS is using to mount. In order to resolve this, you need to add version=1.0 to your FSTAB file then do another sudo mount -a this will work.