Technology Errors

dumpcap: That string isn’t a valid capture filter (syntax error), dumpcap filter syntax

I needed to capture some packets on a server to import into Wireshark on a Windows XP computer but hadn’t done this in awhile so I needed to refresh on how to do this. I ended up using dumpcap to capture the data, then obtain the dump file on the windows computer, and then imported into Wireshark. One thing I had a moment of trouble with was the dumpcap filter syntax. Below are some examples of how to use the filter that the dumpcap -f switch uses.

Basic dumpcap Capture[All Data]:


  1. dumpcap -w /path/to/file

Technology Insights

How to Fix a Dead WRT55AG Version 2 Linksys Wireless Router

Recently I was digging in an old box of routers I have because I was looking for a wireless router to use as a secondary wireless network at my house. The secondary network needed to run WPA but be as secure as possible in every other way so my PSP could connect to it and use the Internet. I located a wrt55AG but the power would not come on and it took a moment but I finally remembered the story behind it. A friend had given me the wireless router saying the lights would not turn on after they used the incorrect plug to plug it in. I don’t know anything about hardware so I decided to give it a go with nothing to lose. Below are the steps taken to fix the router and get it operational again to be used as a secondary wireless router at my house.

Technology Insights

CentOS Linux: What RPM Package Installs the “ls” Command?

I recently noticed a difference of the output from the “ls” command between servers so I wanted to update the package on each server to make sure I was comparing apples to apples. I knew that “ls” was part of a grouping of utilities but wasn’t sure which package. You can use the info command to find out more about a specific Linux command as shown below. Only the first paragraph is shown in the output since its pages long.

Technology Insights

CentOS Linux: Stop Monitor From Going to Sleep Using, Turn Off Powersave

I have a couple of Linux servers at my house and sometimes I will be viewing something on the screen for a long time and will continue to need to look back to the monitor for reference. Anyhow my monitors kept turning off or hibernating after about 15 to 30 minutes. Initially I thought this would be something I could modify in the BIOS of each of these computers but I was incorrect. The way to stop powersave mode in Linux is using the setterm command. Use the syntax below to turn off powersave mode and stop your monitor from going to sleep.

Technology Insights

WordPress: Getting WP Super Cache to Work With WordPress PDA & iPhone

I struggled with getting WP Super Cache in full caching mode to work with a mobile device plugin such as WordPress PDA & iPhone for a long time. Awhile back I actually had given up because everything I was doing appeared that it should work but it wasn’t working properly. Needless to say I recently moved the site to a new server and decided to give it another shot. This time I was able to get WP Super Cache working with WordPress PDA and iPhone with ease.

Please realize that this method makes it so all of the mobile browsers do not cache┬ápages but they also do not retrieve pages from the cache. To configure the below properly you have to realize that there are two different things happening which are the fact that mobile browsers should not cache files and they should not read from the cache. Basically if they didn’t cache files but read from the cache they would be reading the cache of the default template that you see in IE. If mobile browsers cached files then they would be caching the mobile template so when typical browsers such as Internet Explorer or Firefox visited the same pages they would be viewing the mobile cache instead of the default template you have configure.