Blog: Internet filtering

We had a customer report that all browser windows were closing for users and this was increasing in frequency. Most of the users reporting the issue were at the corporate office, which has about 150 users and is where the IT department is located. I performed a remote session with on the users and confirmed the issue. Internet Explorer, Chrome, and Firefox all would close, not crash, at the same time.

My first thought was that some remote assistance and IT management software they had recently installed was causing the issues. We uninstalled the software and the issues continued. My next thought was that something malicious was on the network and was killing the processes remotely. I moved the PC to the guest wireless network and the issues stopped. After moving the PC back to the internal network, the issues began again. After a while, the issues randomly stopped for this user. I moved on to looking at another user's PC. The IT department did not know of any new devices that had been brought onto the network.

Whatever was causing the issues was obviously powerful enough to kill processes. The browsers seemed to be closing at regular intervals, at the top of the hour and half after the hour. I started Process Monitor, Process Explorer, and WireShark, opened the browser, and waited. As expected, the issue occurred again. I started looking through the WireShark logs and did not see anything odd. I looked at the Process Monitor log and found several cmd.exe processes killing the browser applications. At about the same time I saw the cmd.exe commands that killed the browser processes, I saw nxclient.exe processes that called cmd.exe and ran taskkill commands.

I started searching online and found a blog on the NxFilter support group discussing the same issue. This customer has NxFilter for web filtering for several years. They were using version 5.0 of NxClient, which was before the version mentioned in the NxFilter support group. The NxFilter creator responded to that group and said that the client was doing so to force a refresh the user's session, but that this is not the correct behavior. There was a new version of NxClient that fixed this behavior. Version 9.1.3 of NxClient was current, so I updated the customer to use the newer version. That resolved the issues. 



Be mindful about what filtering software you use.  Some web filtering software gathers data on chats.  Software produced by EchoMetrix and sold under the Sentry and FamilySafe brands reads private chats then the company sells information to third parties. The company reportedly collects data on what kids are saying about movies, music or video games in chats carried out through services such as Yahoo, MSN, AOL, and other services.  Supposedly, no identifiable information is disclused because the program does not record children's names or addresses.  This is definitely an example of why it's good to read through the user agreements of the software you use.

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With 3 sons at home, the dangers posed by the dark side of the Internet are a real concern. During a recent visit to Kim Komando’s website, I discovered a totally FREE Internet filtering and control solution for the home called K9 Web Protection. After testing it on two of our three systems at home for about 10 days, it appears to be as effective and custom configurable as other commercial products I have used in the past.[more]

K9 Web Protection ( is protecting almost half a million homes, according to their website, and has been awarded the Seal of Approval from The National Parenting Center (, the iParenting Media Award ( and the IIA Family Friendly Filter ( Additionally, CNET’s Editor Rating is 4 stars (of 5) and the average rating from CNET users is 4½ stars (see

I was also impressed with the philosophy that led Blue Coat Systems to offer this product free for home use:“Blue Coat Systems has been very successful selling a version of this software to Fortune 500 companies and other large corporations. When we became successful, and were looking for ways to give back to our communities, we realized that one valuable thing we could offer was a free version of our Web filtering service for home users.” (see “Why are you giving away this software?”)