Archive for January, 2006

Viewing wireless networks with wigle

I heard about the wigle and restyredwagon websites sites a while back, and finally had a chance to look through their content tonight. If you haven’t heard of these nifty sites, they both contain geographic maps of 802.11 wireless networks. Since the rustyredwagon website overlays wigle data on google maps, you can click a location […]

jot it up

While reading through UNIX powertools tonight, I came across jot. This nifty little utility will print a sequence of numbers, which can be used to iterate through a loop: $ for i in `jot 5` do echo $i done 1 2 3 4 5 Using jot in this way is typically faster than other mechanisms […]

Debugging web applications article

It looks like SysAdmin magazine is running my article Debugging Web Applications in this months issue. If you are looking for ways to debug problematic web servers and applications, this article might be for you.

Monitoring FreeBSD installations

I decided to re-partition my x86 laptop hard drive today, which required me to re-install FreeBSD (the disk label changed rather drastically). After I hit “commit” to propogate the changes, I hit “control-alt-F2” and was thrown into virtual terminal #2. This virtual terminal contained the output from the package extractions, and I found it a […]

Best way to learn how applications work? Dtrace!

I have been spending a good bit of time trying to understand how Apache works, and started to wonder which methods could be used to understand how large software packages work. After pondering this for a bit, it dawned on me that DTrace’s flowindent and ustack() / stack() functions are ideal for reverse engineering software. […]

Correlating truss sys# entries to system call names

While trussing a process today, I came across several lines similar to the following: $ truss -r all -w all -x all -v all -leaf -p 1234 [ ….. ] sys#208(0x0000000F, 0x10009E050, 0x00000000, 0x00000000, 0x00000000) = 0x00000000 [0x10009E050] This line doesn’t contain the system call name, but contains a “sys#” block to indicate which system […]

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