Nov 042012

At the base of these articles there is a simple fact: a simple rm of a file or deleting it via any file manager is not enough to really remove it from your hard disk.

If you really want to delete files from a computer you have to use more sophisticated commands, and in former articles we have seen:

Dban: Darik’s Boot and Nuke (commonly known as DBAN) is an open source project hosted on SourceForge. The program is designed to securely erase a hard disk until data is permanently removed and no longer recoverable, which is achieved by overwriting the data with random numbers generated by Mersenne twister or ISAAC (a PRNG).

Shred : Overwrites the specified FILE(s) repeatedly, in order to make it harder for even very expensive hardware probing to recover the data.

Wipe : Wipe is a secure file wiping utility.

Today we’ll take a look at the package secure-delete that contains some useful programs to delete in a safer way files, memory, free space and/or the Swap space. Continue reading »

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Sep 142011

This is my personal Top 8 of worst suggestions I’ve read, took or gave to other Linux users so far, feel free to add your as comment.

Legend: Q: Question, BA: The bad answer, GA : What could have been a good answer

1) Q: I have a file i can’t read/write/execute with the user i want!

Bad: “chmod 666 file” – This makes the file editable and destroyable by anyone.
Worse: “chmod 777 file” – This makes the file editable by anyone AND sets execute permissions for anyone. This means that any user can edit the file to do something malicious for the next user to (accidentally?) execute it.
Worst: “chmod 7777 file” – Also gives setuid and setgid permission. With this you’ve just given any user permission to fubar your machine, especially if the file is owned by root.

GA: Check which user and group have permission to do the operations you need on that file, subscribe the user to that group and/or change the owner or the group of that file. Continue reading »

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