fstab and octal umasks

The file /etc/fstab defines the various mount points and their parameters (see the Configuration files and directories page). One key attribute is the umask. This is a set of octal values that detemine the permissions of a mount point. It maps to the permissions as follows...

    rwx rw- r-x permissions
    
    111 110 101 binary
    
    421 420 401 
     7   6   5  octal
    
    000 001 010 umask (binary inverse)
    
    000 001 020 
     0   1   2  octal umask

So to define a mount point with those permissions, the umask in fstab must be 0012 (in most cases you can ignore the leading 0). For a full description, see this Linux FAQ.