Sandra Henry-Stocker


Sandra Henry-Stocker Blogs

  • Unix How To: Planting a Tree, Unix-Style

    Posted May 12, 2010 - 9:56 am

    Most people learn the mkdir command on the first day they start using Unix. Along with ls, cd and pwd, it's in the set of the most basic commands that everyone who ventures onto the command line on a Unix system ought to know. It generally takes a while before they learn the more exotic uses of this simple command -- such a creating a branching tree structure with just one mkdir.
  • Review

    Book Review: "Hacking: The Next Generation"

    Posted May 5, 2010 - 11:29 am

    "Hacking: The Next Generation" is a book which quickly moves beyond the basics of why hacking works to modern tools and methods. Its three authors, each a recognized security expert in his own right, have joined together to write a book which is both jammed with practical insights and delightfully readable.
  • How To: Grep Tricks for Linux Users

    Posted April 28, 2010 - 11:39 am

    Here's a couple tricks you can play with grep, several that don't appear to have corresponding support in some of the other Unix versions.
  • Review

    Course Review -- The Art of Exploitation: Bootcamp Edition

    Posted April 21, 2010 - 6:06 am

    I just returned to work following a two-week hacking class. Called "The Art of Exploitation: Bootcamp Edition", this class has pushed me through to the "aha" (I really got it) stage of what hacking really is and how it works. Definitely in the "red team" (attack) camp, this high intensity, short time frame "bootcamp" class went from basics to realistic, seriously complicated hacking within its modest two week time frame.
  • Unix How-To: File Updates in Linux

    Posted April 14, 2010 - 6:42 am

    While the average Unix user is generally satisfied by the date/time stamps that he sees when using the ls -l command, it is sometimes useful to remember that there are actually several time stamps associated with every Unix file. These time stamps represent the last modification time (i.e., the time stamp you see when you use the ls -l command), the last status change time and the last time that the file was accessed. For Linux users, all three of these time stamps can generally be displayed with the stat command.
  • Unix How To: The Linux /etc/inittab file

    Posted April 7, 2010 - 7:55 am

    One of the files that the average Unix sysadmin rarely looks at, almost never changes and yet depends on every time he or she reboots a system is the /etc/inittab file. This modest little file controls what happens whenever a system is rebooted or forced to change run levels. Let's take a look at the configuration lines that tell your system what it's supposed to do when you hit that power button.
  • Alice in Colorland: RGB vs CMYK

    Posted March 31, 2010 - 11:26 am

    Scrunching my face at the differences between the image on my screen and the printout on the paper in my hand, the reason for the two systems commonly used for generating colors -- RGB and CMYK -- finally hit me like a chessire cat landing with a thud on the top of my head.
  • Unix How To: Aliases and Functions

    Posted March 24, 2010 - 3:43 pm

    With the right set of functions and aliases, Unix users can save themselves time and trouble and make their Unix accounts a lot nicer to use. In today's "how to", we're going to look at a simple function for setting up aliases and another that makes an alias-like change to a system command.
  • Stress Testing Web Sites

    Posted March 15, 2010 - 5:25 pm

    If you or your company are setting up a new web site, you might want to know how that web site is going to stand up to heavy traffic. How will it respond, for example, if 50, 100, 200 or 500 visitors are using your site at the same time? Will response time for people on the other side of the country or the other side of the world be significantly longer than response time for people across the street? You can find out how your site will respond to heavy usage without waiting for it to happen.
  • Unix How To: Sed & Awk -- Still friendly after all these years

    Posted March 10, 2010 - 4:45 pm

    Even after decades of using Unix on thousands of systems, I find that it's still fun to discover various convolutions of sed and awk commands to perform command line wizardry. There's a lot more to each of these tools than those uses I make of these commands on a routine basis. Let's take a look at some one-liners you might not yet have tried.
  • Port Knocking

    Posted March 3, 2010 - 11:20 am

    Fred Stluka from just introduced me to port knocking -- a method of opening ports on a firewall by trying to connect with a series of ports in a pre-determined order. The sequence of "knocks" acts like a secret access code -- like tapping out the first couple of bars from your favorite song to tell someone inside that it's you. Similar secret taps were used during Prohibition to ensure that only those who knew the secret knock would be allowed into the speakeasies. These days, port knocking provides a way to forge access through a firewall by using the code.
  • What Does ISO 27001 Mean to You?

    Posted February 24, 2010 - 4:34 pm

    Whether or not you have had any direct experience working with international standards, ISO 27001 (ISO/IEC 27001:2005 - Information technology -- Security techniques -- Information security management systems -- Requirements) might be coming your way. An increasingly popular and comprehensive program for information security, this standard touches on nearly everything that sysadmins do and addresses information security across the organization.
  • Unix How To: Using nmap to Map Your Network

    Posted February 17, 2010 - 2:20 pm

    It is certainly well known that "hacker tools" can be used for many legitimate purposes. Nmap, the Network Mapper and security scanner is no exception. These days, it is used routinely to identify the operating systems, applications and software versions running on targeted systems.
  • Black Hat DC 2010: Using the Dark Side for Good

    Posted February 10, 2010 - 4:00 pm

    The Black Hat Briefings came to the Washington, DC area (Arlington, VA) last week, drawing roughly a thousand representatives from the black and white hat communities together to learn how to attack and defend our systems. With a keynote by Greg Schaffer from the Department of Homeland Security and three tracks of briefings that covered everything from "the big picture" to tricks you can play with metasploit, this hackerfest took on the global perspective on hacking while simultaneously drilling down to the nitty gritty on various attack methods.
  • How Motion Detection Cameras Work

    Posted February 3, 2010 - 3:58 pm

    Monitoring your data centers and building access points with CCD cameras can represent a boon to your overall security, but you need to know a little about camera terminology to make the best use of them. Don't think about "aim and shoot" when you think about these cameras. Think, instead, about how you might go about detecting motion in a series of still images.
  • Unix How To: Peering at a Process with lsof

    Posted January 27, 2010 - 12:35 pm

    You have probably used lsof from time to time, probably when tracking down some sort of problem. But maybe you haven't tried all of its permutations or looked at it just to get a deeper understanding of how some particular process works. Let's look at one particular lsof command that can provide a lot of insight into a single process.
  • Review

    Book Review: Inside Cyber Warfare: Mapping the Cyber Underworld

    Posted January 20, 2010 - 11:40 am

    If you think you have a good handle on how big a problem hacking has become for the world at large, think again. Inside Cyber Warfare is going to change your view completely. If you think it's just bored teenagers and introverted misfits that are attacking systems, you're dangerously out of touch. It's organized crime and the political underground. It's hackers hired or condoned by corrupt bureaucracies. And they're out to steal money and industrial secrets, fight battles over public opinion, destroy the effectiveness of enemy groups and break critical infrastructure.
  • How to: The Unix Interview

    Posted January 13, 2010 - 11:25 am

    When you need to interview a candidate for a Unix sysadmin position, it's important to get a feel for the individual's skill level and breath of experience. A person's resume will tell you a lot, but resumes typically inflate or obfuscate a candidate's experience.
  • Unix How to: Thinking in Unix Time

    Posted January 6, 2010 - 1:27 pm

    The new year rolled in at 1262304000, Unix time that is. It's a little hard to imagine that Unix is now more than 1.2 billion seconds old. Seems only yesterday that I was trying my first pipes and grep commands while thinking "Wow, this is groovy". OK, maybe not quite "groovy", but close!
  • Unix How To: Unix Resolutions for 2010

    Posted December 30, 2009 - 10:35 am

    Midnight, Dec 31st is rapidly approaching and there's no better time than this to resolve to be the best Unix sysadmins we can be. Here are some New Year's Unix Resolutions worth keeping.
  • Unix How To: Using Basename Wisely

    Posted December 23, 2009 - 1:56 pm

    The basename command can come in very handy when you want to strip down a file reference that has dragged along its full pathname. There's an extra trick you might not know about and a performance issue you may not have considered. Let's take a close look at this modest little Unix command.
  • Solaris How To: Logging for FTP on Solaris 10

    Posted December 16, 2009 - 7:24 pm

    If you're still using ftp and would like to log your transfers, you might have to look around to figure out how to do this on Solaris 10. The answer lies with a command called svccfg (for "service config").
  • Unix How To: Sorting Log Data

    Posted December 9, 2009 - 1:25 pm

    I have a request for you: I was recently given a task of monitoring serveral log files and it has become quite a chore. My main problem right now is to display those log files sorted by a specific column. I have attempted to use awk, but I'm having some challenges.
  • Unix How To: Repeating Commands in Bash

    Posted December 2, 2009 - 11:56 am

    Typing "history" or pressing your up arrow key might make using Unix systems a little easier, but these little tricks only scratch the surface of how you can work with previsouly typed commands when you're using bash.
  • Review

    Book Review: The Book of Inkscape

    Posted November 25, 2009 - 1:02 pm

    Years ago, I discovered Gimp, the free tool that provides Photoshop-like processing of images. Only recently have I come across Inkscape -- the free graphics editor that competes with the likes of Adobe Illustrator. Even you can prepare professional quality graphics if you take the time to learn this fabulous tool. And now here's a book to teach you everything you need to know.
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