Learn to use extended file attributes in Linux to boost security

“With all the talk of enhanced file system security and security
frameworks, some of the basic file protection enhancements provided
by the Linux kernel have been forgotten. While there is certainly a
distinct place for security applications like SELinux, GrSecurity
and others, there are simple means for securing files as well. ACLs
and extended attributes for files are simple and easy to use, and
can go a long way in securing files.

“The first tools to use with extended attributes is chattr,
which changes file attributes for files, and lsattr which lists
those attributes. There are a number of extended attributes you can
add or remove from files, including “a”, which makes a
file append-only, and “i” which makes a file immutable
(cannot be modified, deleted, or renamed, nor can any link be
created to the file). There are other attributes that deal with
compression, undeletion, secure deletion, and journaling as
well.”

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