Extended file attributes

Extended file attributes can provide greater file access restrictions.

Only available on ext2 / ext3 filesystems.
Attributes cannot be set or read on NFS mounted filesystems, but are in force.
Can only be changed by root.
Can be changed back by cracker who has gotten root.
Includes such attributes as
a - Append only
d - Not dumpable
i - Immutable
S - Synchronous writes