Monthly Archives March 2005

Fedora Core 3: Mystery Solved

Categories: Rants and Rambling.

You may recall the problems I had downloading the Fedora Core 3 ISO image a while back. Well, I did finally get a good copy downloaded and installed. I did a bit of analysis on the downloaded images, and determined that there had been a couple of four-byte changes. This was something of a mystery, but nothing notable.

I was mentioning this to Rohan just now, and he twigged on the “four bytes” part of this. In particular, he wanted to know what the bytes had been changed from and to.

In the non-corrupt image, there is a byte pattern of “D1 1E 21 0D” starting at (decimal) position 634,912,768 and at decimal position 11,875,12,320.

In my first download (which was paused and resumed over several days), that set of bytes at 11,875,12,320 was inexplicably “C0 A8 00 6C.”

In my second download, both sets were “C0 A8 00 6C.”

In the third download (several days later), the image was uncorrupted.

Rohan’s specific question was: “So, do those look like reasonable IP addresses?”

Let’s see… C0 A8 00 6C…

Oh. My. God.

Let’s check something about the bytes that it replaced… they’re

SBC Internet Services - Southwest SBCIS-SBIS-20930 (NET-209-30-0-0-1) 
PPPoX Pool bras2.rcsntx SBC209030032000031209 (NET-209-30-32-0-1) 

Yep. That’s my ISP.

My NAT saw its external IP address in the incoming data, and decided to change it to the internal IP address of my machine to “fix” things.

I’m using a different NAT now.

Plants Create Genetic Backups?

Categories: Health and Science.

Recent findings suggest that certain plants might have the ability to revert to gene sequences present in their grandparents’ DNA. One theory is that these reversions are activated if the genes passed to a plant by their parents cause them stress. It’s not clear where the backup copies of genetic information are being stored yet.

If these findings withstand scrutiny, and if such mechanisms also exist in animals, the implications for genetic engineering are staggering.

Texas v. Vonage

Categories: VoIP.

Following an incident in Houston in which a Vonage subscriber was unable to reach 911 in an emergency, the Texas Attorney General has filed suit against Vonage. The suit seeks suitable notice to subscribers about the (rather crippling) deficiencies in Vonage’s 911 service.

There are a few problems with the way that Vonage currently handles 911, and I’ve been warning people about them for a couple of years. The first is that, by default, dialing 911 simply plays a recording saying “you don’t have 911.” You have to activate 911 service before you can use it, and apparently Vonage doesn’t make this clear enough to new subscribers. Further, it takes several days after such a request before 911 service becomes active.

The second problem is that 911 calls (with very rare exception) are routed to an administrative number for the emergency center, not the 911 operators themselves. So, the person answering the phone isn’t able to actually dispatch emergency services; in fact, by and large, they’re simply a secretary without any emegency training at all. A correlary to this is the fact that, in many locations, calls to Vonage’s 911 service outside of business hours will simply go unanswered.

The third and final problem is that (once again, with rare exception), Vonage has no technical means to transfer location information to the emergency centers. Even a very technical friend of mine using Vonage as a primary line replacement was unclear on this fact. She thought that the fact that she gave her address to Vonage in the process of 911 service activation meant that the 911 center would have this information available, and Vonage did nothing to inform her otherwise. So, even people working in the VoIP industry lack the knowledge to figure out this information; what hope does the average consumer have?

Don’t get me wrong. As long as you can wait until business hours to have your unexepected emergency, have figured out that you need to register for 911 with Vonage, aren’t in the multi-day activation period, limit yourself to emergencies that leave you physically and mentally capable of giving your location, and don’t mind untrained personnel fielding your emergency calls, then using Vonage as a primary line replacement is just fine. And that may be good enough for some people. But I agree that it needs to be a choice people make for themselves with adequate information.

Enova Oil

Categories: Food and Health.

Arthur Daniel Midlands has recently launched a new cooking oil in the U.S. that they’re marketing under the name “Enova.” The marketing claim is that “less Enova is stored as fat in your body than other cooking oils.” What is this stuff?

Structure and Process

According to their literature, the key difference between Enova and “conventional” cooking oils is that most plant oils are composed of triglycerides, while Enova is predominantly diglycerides — in particular, diglycerides of a very specific shape. My organic chemistry knowledge is very rusty, but the general idea is that the fats that we ingest are generally (always?) fatty acids attached to glycerol molecules (CH2OH-CHOH-CH2OH).


In triglycerides, all of the OH radicals are replaced by carboxyl groups which attach long hydrocarbon chains. The nature of the fat (both dietarily and physically) varies greatly based on the structure of these chains. Unsaturated fats, for example, have some of their hydrogen atoms replaced by carbon double-bonds. Predictably, diglycerides and monoglycerides replace only two or one such radicals, respectively.

Saturated Fat! It’s What’s For Dinner!

Back to Enova: apparently, the manufacturing process involves starting with traditional (canola, soy) oils, breaking the triglycerides down into glycerol and fatty acids, and then recombining them in the presence of an enzyme. It’s not clear from the literature whether this enzyme catalyzes reattachment to the 1,3 positions or retards attachment to the 2 position of the glycerol — but the net effect is that you end up with mostly 1,3-diglycerides.

Dietary Impact

Now, the theory is that, since the human body can’t easily reattach fatty acids to the 2 position, processing of these fats after being absorbed is different; instead of being reconstituted and available for deposition as body fat, they are instead used in the liver for beta-oxidation. (Intuitively, it would seem that this would simply make whatever fat would have otherwise been used for that purpose to be deposited in fat stores instead — which, although not particularly useful, would make their marketing claim technically true).

Studies on ingestion of 1,3-digylcerides have produced conflicting results. Findings in Japan indicated that diglycerides may reduce visceral fat more than other areas. This would be significant if true, as recent findings on fat have reinforced earlier observations that viceral fat causes significantly more health problems than fat elsewhere. This study also observed significant fat decrease in subjects’ livers. However, a subsequent study in the U.S. was unable to replicate either result.

Both studies showed that the diglyceride group lost measurably more weight than the control group, so there is probably some benefit there.

In no case has any beneficial impact on blood serum levels of cholesterol or triglycerides been observed. This is particularly interesting, because the reported weight loss alone would generally be expected to cause a measurable decrease in LDL cholesterol levels.


So, the published information sounds pretty good — or, at very worst, innocuous. It’s a bit pricey, and I’m always personally wary of highly synthetic foods (e.g. corn syrup), but it doesn’t seem to have any outright warning signs. That said, there are a couple of items of potential concern that are worth noting.

Looking at it from the perspective of just another vegetable oil, there are some interesting things to note. If you check the nutrition label, you’ll see that it’s lower in saturated fats than even canola oil is. That would generally be good; saturated fats tend to raise LDLs. However, compared to most oils, the polyunsaturated fat content is somewhat high. Polyunsaturated fats tend to drop overall cholesterol levels, both LDL and HDL. That’s not bad, but it certainly isn’t as good as monounsaturates, which tend drop LDLs while raising HDLs. So, from a pure fat profile perspective, this looks like it’s not much of an improvement over, say, canola oil; and it may be worse.

The other interesting thing to take note of is the ratio of omega-6 fatty acids to omega-3 fatty acids. Enova has a ratio of about 10:1, while most vegetable oils are closer to 3:1. Although studies are currently ongoing, some researchers believe that higher percentages of omega-6 may cause higher blood pressure and chronic inflammation. (see

[Edit: cleaned up many typos and cited a relevant study]

QoS Considered Harmful

Categories: VoIP.

Cringlely has an interesting take on QoS. What happens when the ISP tags the traffic for its own services to have a higher class of service than that of all those third party services? I’ve heard lots of arguments that best effort is good enough for VoIP if you have sufficient bandwidth. But that will fall apart pretty quickly if it has to compete with lots of higher priority traffic.

This could be the big ISP’s best shot ever at breaking that annoying end-to-end internet. Now, Cringely did not present any evidence the ISP’s were actually doing this–but I keep hearing more and more carrier-associated people claiming that VoIP is not deployable without QoS. This, in spite of all the services that work “well enough” without it.

(And yes, I just violated my on policy of not posting things already on slashdot again.)

Spam Getting Bizarre: “We have learned from the Internet that you are interested in tents”

Categories: Silly Stuff.

I don’t think any comment is necessary, but this is certainly… um… unlike any other spam I’ve ever received.

To Whom It May Concern,

We have learned from the Internet that you are interested in tents. We have been in the tent manufacturing business for many years and are currently in the process of expanding and our customer base. We are quite excited about contacting you and the potential for establishing friendly business relations with you as well as sharing the mutual benefits.

We specialize in high quality, high performance tents offered to our cutomers at competitive prices. We are able to supply a wide variety of tents manufactured to the specifications and requirements of the customer. We would be interested in receiving more information from you so we could submit a suitable offer to you.

Feel free to view our website:

If you do not wish to receive any more information, please let us know and we will take you off our mailing list.
We are awaiting your favorable response.


Richard Zheng
Marketing Director
Xia Men Jiao Xia Trade Co., TLD
No.89, CangHong Rd, HaiCang Xia Men China(361006)
Tel/Fax: 0086-592-5527336
Mobil: 0086-13806069172

Random Trademark Fact: “Push to Talk” now free

Categories: VoIP.

I have, until now, been under the impression that the term “Push to Talk” is a trademark of either Motorola or of Nextel, and that using it in a more general sense was generally asking for trouble.

Then, today, I spotted a Verizon ad advertizing their “Push to Talk phone.” The capitalization is theirs, which gives it almost a trademarked feel. However, there isn’t any indication of trademark ownership anywhere in the ad (aside from the places you’d expect it — next to the Verizon logo, for example).

So, I checked with the USPTO (which doesn’t let you bookmark into trademark searches, but you can go here, click on “trademark search,” then “basic search” and type in “Push to Talk”), and apparently, Nextel (who had previously registered the term “Push to Talk”) abandoned its use of the trademark in November of 2004.

That said, the term “Push to Talk Worldwide” has been registered as a service mark in a VoIP context by an individual (not a company). Also, Motorola is still maintaining a trademark on the term “P2T,” although that registration explicitly says that they don’t claim “PTT” as a trademark. “PTT” used to be registered by a company I’m not familiar with, but its use was abandoned in 2000.

So, there you go. For the time being, it appears that you can use “Push to Talk” and “PTT” without any fear of the lawyers coming after you1. In fact, they’ve probably become common enough that trademarking them would be pretty much impossible.

“PoC” doesn’t appear to be registered in the U.S.; although, any such registration would probably be difficult due to nontrivial overlap with the trandmarked name of “POC,” owned by Physical Optics Corporation, which makes data switching equipment for telecom and datacom networks.

1 Anyone taking legal advice from a blog deserves any trouble they get.

Followup: The Guilty Party

Categories: VoIP.

So, it turns out the ISP — or at least one of them — who had started blocking port 5060 so as to disrupt VoIP services is a little company called “Madison River Communications.”

The problem appears to be cleared up now. And the fine is big enough that it would definitely deter… umm… most people who had to pay it out of their own pocket?