Thoughts on Antivirus

I get this question a fair amount. Here is the latest version from someone on Facebook: “To all the computer wizards out there: Which antivirus do you suggest putting on a computer?” My response…

Short version: Spend your money on backups instead.

I think I am in the minority in the industry on this, but I tend to recommend “none”. Antivirus software is a bit like insurance. You are going to pay something (dollars, at least some slowdown, and potential problems) all the time to potentially avoid paying a big something later.

No antivirus software can completely protect you from reckless behavior, and if you’re responsible, the risk is probably acceptably low. By “responsible”, I mean things like: don’t open attachments or click on links you were not expecting, regularly apply updates to your OS and browser, and only install software from trustworthy sources.

For the typical home user, the cost of recovering from a virus is pretty minimal, if you have backups. That is where you should focus your energy and/or money. And always test your backup method to make sure you can actually get your files off of it!

Update: Running Microsoft Security Essentials is probably reasonable. It’s free; you get it as part of Windows Updates.

My tcpdump Idiom

This is how I like to run tcpdump these days:
sudo tcpdump -U -s 0 -w - port 80 | tee DESCRIPTION-$(date +%s).pcap | tcpdump -lvvnr -

This dumps out a .pcap file I can open in Wireshark later, but also shows the tcpdump human-readable representation in real-time.

Wiktel is Hiring

We’re looking to hire a system administrator:

Email me a resume:

Comparing Internet Options

To compare Internet service options intelligently, you need at least the following information…

Price, Contract Length, Early Termination Fees, Required Services (landline/wireless phone, cable)

These are pretty self explanatory.

Download and Upload Speeds

These speeds should be “goodput”, or actual measurable throughput after overhead. For example, some technologies have overhead rates of up to 20%. If a provider advertises a 10 Mbps service offering, the actual “goodput” might be 8 Mbps. Or, they might be compensating for the overhead and provisioning the customer to 12.5 Mbps so their “goodput” is 10 Mbps.

Some providers offer an option where the customer’s speed is higher for a short burst, but drops down for sustained use. Make sure that you’re looking at this as a separate feature. Only sustained speeds should be directly compared to other sustained speeds.

Data Caps

With uncapped service, you can download at your provisioned speed as much or as little as you want.

Traditionally, wireline providers sell uncapped services. However, that’s not universally true today. Various cable and DSL providers are implementing caps, though they’re generally in the 100-250 GB range whereas cellular providers have caps in the 2-5 GB range.

One source quotes a studying saying the average Netflix customer uses 40 GB per month (just for Netflix).

If one of those average customers was using service from a cellular provider like AT&T or Verizon, they’d get a huge bill for the usage above 4 GB. With a provider like T-Mobile, they would’ve had their connection speed drastically reduced after the first 2 GB of transfer. If they were using WildBlue satellite Internet service, their connection would’ve been slowed after the first 7.5 to 25 GB, so they probably would’ve been unable to use Netflix for the rest of the month.

Latency (Delay)

Satellite connections have very high latency.

Imagine a satellite connection with 1.5 seconds of latency. Adding 1.5 seconds to a large file download or waiting 1.5 seconds for a full-length streaming movie to play is no big deal. But adding 1.5 seconds to a web page load and then another 1.5 seconds for the images to start loading and possibly more round-trips, and it’s all pretty annoying.

And 1.5 seconds of delay on a VoIP telephone call would make it all but unusable, as you’d be constantly talking over the other person. And 1.5 seconds of delay would make Internet video gaming completely useless.

“Jitter” (Packet Delay Variation)

This is the variation in latency. Interactive applications like VoIP are sensitive to jitter. Streaming services can compensate for jitter by using a larger buffer, which adds total delay (which may not be a perceptible problem, as in the case of a small delay before a full-length streaming movie).

Shared access networks like cellular, satellite, fixed wireless, cable, or GPON fiber-to-the-home will generally have more jitter than a point-to-point connection like DSL or active Ethernet fiber-to-the-home. This unscientific test shows the concept.


Assuming the provider runs a clean, uncongested network, you only care about these parameters over the “last mile” piece from the customer to the provider. Note that this is an important assumption. If there are concerns that a provider might not be running an uncongested middle-mile network, then you’d need to compare to an independent third-party destination.

To be fair to satellite Internet access, it’s available essentially everywhere (in North America).

To be fair to cellular Internet access, it’s mobile. You can have a cellular modem and use your laptop most places, including in a moving car, though obviously it should not be one you’re driving!

TI Calculator Link Cables (2.5mm 2ft)

If you’re looking for a link cable for TI calculators (TI-86, etc.), I’ve got 7 extra in brand-new condition. Specifically, these are 2 ft cables with a right-angle 2.5mm male TRS connector (“phone plug”) on each end. For those of you looking to use this in an audio application, these are “stereo” cables. Email me. I’m looking to get rid of them, so I’d only be charging to cover the cost of an envelope and shipping.