Need to physically secure a Linux machine


If you are running a Linux machine in production you have to make sure it is physically secured. The reason for this is because if someone can physically access your machine they basically have access at the root level. This is because in Linux one can make changes to the kernel prior to booting. This is particularly easy if the machine is dual-bootable. Basically to make changes one would:

1. Highlight the Linux installation in the list and press “e” to edit
2. Highlight the kernel option and press “e” to edit
3. Add “single” to the end of the line and press enter
4. Select “b” to boot into single-user mode

In a non-dual boot environment one would just press “e” during the start-up process to bring up the kernel option.

Taking those four steps will grant someone access to your machine at the root level. At that point an unauthorized user could do anything they wanted to including changing the password for root. After doing so and rebooting the machine, they could continue their malicious activity either on or off-site.

That ability to easily gain full control to a machine and potentially an entire data network is why physical security is so important.

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About brvanlanen

Just a thirty-something guy currently hanging it up in the greater Green Bay area. My post-high school educational background is mainly in the Information Technology field. Specifically I have an A.A.S. in Computer Network Systems and a B.S. in Information Systems Security, both from ITT Technical Institute, in addition to A and MCDST certifications. In my free time I enjoy spending time with my family, cooking and sports. My Christian faith is also important to me as a Missouri-Synod Lutheran and all my children attend a Lutheran grade school. When it comes to political leanings I am a conservative first and foremost which you will discover rather quickly. As for sports I am a huge fan of the Green Bay Packers.

Posted on April 17, 2009, in Linux, Security, Technology. Bookmark the permalink. Comments Off on Need to physically secure a Linux machine.

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