brent timothy saner on 3 Aug 2009 15:40:20 -0700 |
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Edmond Rodriguez wrote: I have a very old drive that I figure I might be getting rid of at some point, but I still use it with the very old machine. I have been deleting personal files off of it, but leaving system files and other things on it. Say many personal files were removed not using shred, or it is a file system where shred is not as effective. > it's actually not a TERRIBLE idea, but the problem with that is even if you overwrite that particular free space with random data, the system files themselves could have been written over but the journal still exists, which is a security concern. beyond even THAT, a lot of the high-end professional data forensics places can recover raw data from a hard drive even if the entire thing has been zeroed out. it's terribly expensive since it involves nasty things like magnetic measurement and the like if i recall correcty, but they can usually do it with things up to i think two or three deletes/write overs. that's why things like dban do a minimum of three passes (whole disk writes) and shred's default is, i believe, 25 passes (which is really overkill 99.9% of the time, so you can define a different # of passes). but if you're just worried about masking the data that might contain billing information or the like, i'd go with just two or three passes (unless you're in the NSA or somesuch and these are national secrets or something)- but they should be whole-disk. it's a kind of all-or-nothing sort of thing, quite unfortunately. using shred on a particular file is more geared towards avoiding something like someone just running testdisk and grabbing the file from the journaled changes- in other words, it only targets the inode(s) the file occupies (well, occupied once you run shred). i hope that was a clear enough answer :) -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.11 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkp3Z0AACgkQ8u2Zh4MtlQo/JgCgg+iCEusLgdPA4fXLI4xwb2UO A4AAn30KvUAtlujbAgOnAnsBUO3nz9pm =zNDR -----END PGP SIGNATURE----- ___________________________________________________________________________ Philadelphia Linux Users Group -- http://www.phillylinux.org Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug
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