It happens every now and then to have to do a complete cleaning of a system. Maybe you get a computer from an employee who is gone, or a server must be abandoned, or simply you need to reassign a computer and to be sure that all data are no longer readable in any way.
Do you think that a rm or formatting is enough?
Sorry, but if you think so i must say you are wrong, a rm a fdisk or something like that could be easily canceled, so you need something better…like DBAN
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You are root on your system, you do a rm of a file and get a “rm: can not remove` test ‘: Operation not permitted” is this possible?
Yes, if there are any special extended attributes set on your filesystem.
The “interesting” thing is that also some rootkit use these attribute after have changed some binary (ps, netstat) so restoring the originals it’s a bit harder.
But don’t worry in this article i’ll present you the lsattr and chattr commands that will help you in list and manipulate the extended attribute on your Linux box
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After my previous article 7 Practical uses of Openssl I have received many comments and suggestions of other possible uses of this excellent program.
With this article, i’ll show you other uses of the openssl command used from the command line.
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In a previous article we saw the basics of encryption and asymmetric key used in the e-mail. On Linux the most used and popular programthat deals with security and encryption is OpenSSL .
OpenSSL is an open source implementation of the SSL and TLS protocols. The core library (written in the C programming language) implements the basic cryptographic functions and provides various utility functions. Wrappers allowing the use of the OpenSSL library in a variety of computer languages are available.
Versions are available for most Unix-like operating systems (including Solaris, Linux, Mac OS X and the four open source BSD operating systems), OpenVMS and Microsoft Windows. IBM provides a port for the System i (OS/400). OpenSSL is based on SSLeay by Eric A. Young and Tim Hudson, development of which unofficially ended around December 1998, when Young and Hudson both started to work for RSA Security.
Today we will see some practical uses of programs that rely on OpenSSL.
Sometimes it happen to find in our file system files with strange names, with that i means files with non-alphanumeric characters or spaces between different words, maybe uploaded by users, or files produced by mistake by someone or some program, and unfortunately is often not trivial to do a mv < file > or rm < file >.
Let’s see how to get rid of these horrors. Continue reading »