Filesystems, Disks and Memory

Hmmm...well I had not heard of /dev/random either... I see that SunOS has a /dev/random and a /dev/urandom symlink to it. I didn't find anything with man -k. I'll look around for some docs on this thing.

As for just writing zeroes once, yeah it's probably good enough if you don't have physical access to the disk. But to take a disk with sensitive data, write zeroes to it and then make it available to the web would give a security guy a heart attack.

Suppose a write operation failed because the disk is flakey? A good driver will detect that and arrange for the write to return -1. But bad drivers exist. And few programmers do a good job of checking return codes anyway. Later on, someone might get the data with a lucky read. And this line of "reasoning" applies equally to a disk that has been wiped a thousand times. Security guys think this way...

Just as a side note:

HP-UX famously lacks a /dev/random capability which every other major vendor implemented long ago. That is one of the reasons that extablishing an ssh connection from a HP-UX box is relatively slow -- entropy (used for generating keys) has to be gathered from the system which is much slower than pulling it from /dev

Dont know what the 13 th level here refers to.

i think the /dev/null is present on all unix flavors and that can be a more generic way.

what say buddies

While I know that this is an old posting, I wanted to put my 2 cents in. If you really want to protect the sensative data, replace the drive. It's cheap, the hardware would be faster, and the disk would last longer. Take the old drive and put it on the shelf so that you could get the sensative data back (if you ever needed to).