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Why MAC address filtering doesn’t help security

The other question that came out of my recommended DD-WRT settings was why not filter MAC addresses. I hate to be flip, but MAC address filtering doesn’t help, so why bother?

The reason is because your MAC addresses are broadcast as part of the network traffic, and it’s unencrypted. So your MAC addresses aren’t any secret at all. So it doesn’t do any good. One could argue it doesn’t do any harm. But it adds an extra step every time you put something on your wireless network. Why go to the inconvenience if you don’t gain anything from it?

Read More »Why MAC address filtering doesn’t help security

Available diameters of tubular O and O27 track

A frequent question, especially for those who are just discovering or rediscovering vintage Lionel and Marx trains is what sizes of track are (or were) available, and how many pieces come to a circle.

Unlike other scales, Lionel marketed its track by diameter, not radius. As you undoubtedly remember from geometry class, radius is the distance from the center of the circle to the edge, while diameter is the distance from edge to edge. So a circle of O27 track is approximately 27 inches wide. O27 track stands about 7/16 of an inch tall, while higher end O gauge (also sometimes called O31) track stands about a quarter inch taller, at about 11/16 of an inch tall.

Read More »Available diameters of tubular O and O27 track

Can you mix Lionel and Marx track? Yes, pretty much.

Here’s a question from the search engines: Can you mix Lionel and Marx track?

Generally speaking, yes you can. Just stick with O27 track, and you can mix Lionel, Marx, and K-Line as needed. Dad had a mixture of Lionel and Marx track in the 1950s–my theory is that someone tipped my grandfather off that you could buy a Lionel O27 starter set, expand it with cheaper Marx track, and once you had the track assembled, no one would know the difference. When we set his layout back up in the mid 1980s, we added some K-Line O27 track, because it was what we could find. I have a mixture of all three brands to this day.Read More »Can you mix Lionel and Marx track? Yes, pretty much.

Non-derailing Marx switches

The Marx 1590 is the best O27 switch ever made. It’s durable, works well with all makes of trains (just put a track pin in the center rail where the switch pivots so that Lionel trains can pass), and can run off accessory power without modification.

The only downside is that it (allegedly) can’t be set to automatically switch to a position to accommodate an approaching train like a Lionel 1122, which makes it unusable in a reverse loop. That’s true if you wire them the way Marx said to wire them.

Here’s how I wire them to get that coveted feature.

Read More »Non-derailing Marx switches

Building an up-and-under layout with a K-Line trestle

Taking the advice of several people, I worked on my train layout yesterday. I disassembled my L-shaped layout of two 4×8 tables, rearranged them to make an 8×8 area, and now put down a combination of Lionel and Marx wide-radius track.

As always, there was something to learn.I made an up-and-back-down loop with a modern K-Line 24-piece trestle. I think K-Line makes the best trestle on the market today and it’s the one to get, unless you happen to find a used Lionel or Marx one and can get it cheap. (Make sure all 24 pieces are there!) The K-Line trestle is intended to sit right under each track joint. Lionel and K-Line track ties actually sit right on the trestle. Marx ties are spaced just far enough apart that the trestle fits snugly in the gap. Neither arrangement causes a problem. You place the trestle piece, then drop two metal clips in place and screw them down tightly enough to hold it together.

But when you have a mixture of Marx and any other track, those track joints cause a problem. They’re too close together for the trestle to fit in between, but too far apart for them to sit securely. The problem is most pronounced on curves. So what I ended up doing was turning the trestle slightly to get more available area to hold the ties. It worked.

Another possible solution is to get out a slotted screwdriver and start prying up tabs and moving ties around. I opted to dink around with the trestle pieces instead.

XTrkCad model railroad track software is going open source

XTrkCad, one of the many model railroad track planning programs–and the only one I know that has both Windows and Linux versions–is going open source. This also means the program is now free.

You can’t download the source code yet but you can download binaries, enter a registration code, and play with it. I’ve been doing just that.One thing I noticed right away when I started trying to use it to plan a layout using Lionel and Marx O27-profile sectional track–which it doesn’t support directly, so I had to enter the track, confusingly, using the “custom turnout” tools–is that the model railroad and toy trains people measure track differently.

A Marx or Lionel O27 curve isn’t an O27 curve in XTrkCad. It’s a curve of radius 12.5 and angle of 45 degrees.

Here are some measurements. Keep in mind this is what they’re supposed to be. Manufacturing tolerances and the effects of age sometimes cause these measurements to be off. Some of my vintage track is off by 1/8 inch or more.


I happen to know that O27 and O34 tubular track use a 45-degree angle, and that Lionel and K-Line O42 tubular use a 30-degree angle. Unfortunately I don’t have a piece of K-Line O54 or O72 sectional tubular track to measure.

Since O42 track is supposed to be 12 sections per circle, and 180/12=15, I believe to calculate the angle measurement of O54 and O72 you can divide 180 by the number of O54 or O72 track sections in a full circle, then multiply that result by 2. The math works for the O27, O34, and O42 track sections I have, but since I don’t own any K-Line O54 or O72 track I can’t be certain.

Also, confusingly, traditional O gauge switches are straight turnouts in XTrkCad, even though one leg of them is curved. Here are the parameters I got by measuring a Lionel 1121. The measurements are close enough to represent Marx or Sakai O27 switches:

Diverging length: 8.5
Diverging angle: 45
Diverging offset: 3.75
Overall length: 8.75

And here’s what I measure on a Marx O34 switch.

Diverging length: 11.375
Diverging angle: 45
Diverging offset: 4.5
Overall length: 11.188

I believe the diverging angle would be 30 degrees on a Lionel or K-Line O42 switch, but since my vintage Marx and American Flyer locomotives won’t make it through modern O42 switches, I don’t have any of those to measure.

I’ve already used the software to draw a layout using Marx O34 track that will allow two-train operation with room on sidings for three additional trains. It’s much easier than setting up track on the floor and measuring it to see if it will fit on the table. And you can do your layout and then print an inventory to compare what you have with what you need. Not having enough track to mock up a layout isn’t a problem anymore.

On the computer some of the things I want to do don’t quite fit; if the track measurements are slightly off, the solution is to cut a section of track to move things a bit, or, if they’re off by less than a quarter inch or so, force it. O27 track has a lot of give, and, like I said, manufacturing tolerances and the effects of time can cause real-world track to not match the published standards.

Fun with gasoline… Wait, that sounds bad. How to save gasoline.

Gas prices are driving me up the wall. I’m glad I opted for a Dodge Neon and not a Dodge Avenger last year when I bought a car, since the Neon gets better gas mileage, but right now the VW Jetta is tempting me and is 45 MPG sounds really sweet (my Neon gets 25-30 driving locally and about 35 on trips). My lease is up in two years, so I’ll get it right then. Until then, I’ve gotta do what I can. Yes, small cars are more dangerous than big cars, but if most people drove smaller cars and didn’t drive like they have a death wish, that wouldn’t be such a big deal now, would it?

So I went hunting for gas-saving tips. I found a bunch. Nineteen, I think.

First things first: Bookmark Punch in a zip code, and it’ll give you the lowest fuel prices within a radius you define. More importantly, it lets you watch trends. More on that in a second. Also bookmark They’ve got some gas saving tips (not as many as I’m about to give you) along with every other thing imaginable.

1. Buy the same brand and type of gas whenever possible. Your car’s computer adjusts to the fuel you use. Using a different brand of gas every tankful doesn’t give the computer a chance to adjust, so buying at a different station to save a penny a gallon can end up costing you money.

2. Inflate your tires properly, and check them once a month. You can assume you’re going to lose 1 PSI per month. There’s a sticker on your door that gives the manufacturer’s recommendations. Go with the higher number if one’s given. A tire’s maximum PSI is listed on the rim of the tire itself. Don’t inflate to the maximum, because you gain 1 PSI for every 10 degrees’ temperature increase, but if there’s a discrepancy between the tire maker and the car maker, meeting them halfway will improve gas mileage. And make sure your wheels are properly aligned.

3. If your car’s going to idle for a minute or longer, such as at a drive-thru, shut off the engine. It takes less fuel to start the engine up again than it does to idle for just 10 seconds. Better yet, park and go inside.

4. Use the thinnest-viscosity oil your car manufacturer recommends, usually 5W-30. A low-viscosity synthetic can improve your gas mileage by 3 percent.

5. Replace your air and gas filters periodically–usually once a year.

6. Drive slower. Every one mile per hour over 55 MPH decreases your gas mileage by 1-2 percent.

7. Avoid sudden acceleration and braking, and use your cruise control whenever possible. Aggressive driving–tailgating, weaving, speeding–decreases drive times by about four percent on average, but can increase fuel consumption by 39 percent.

8. Clean out your car. Excessive weight harms gas mileage. Each 100 pounds in your car decreases gas mileage by about one-half mile per gallon.

9. Replace your spark plugs on time, and replace them with high-performance spark plugs, such as Bosch Platinums, and gap them properly. Platinum plugs don’t wear out as quickly, and while the jury is out whether platinum plugs inherently give better gas mileage, a set of old platinums will have an edge over a set of old cheap plugs. Two bad plugs can decrease your gas mileage by 20 percent.

10. Use your air conditioner on the highway, since open windows increase drag. Turn off the air conditioner and roll down your windows in stop-and-go traffic. And in the winter, using the defroster decreases your gas mileage, although using the heater won’t.

11. It only takes 10 seconds in warm weather and 30 seconds in cold weather for most engines to warm up. Warming up longer than that burns fuel without giving much other benefit.

12. Use overdrive if your car has it.

13. Avoid gimmicks that claim to increase gas mileage. Simple maintenance makes a bigger difference than anything else you can do.

14. This should go without saying, but don’t drive out of your way looking for the lowest gas price. Remember the size of your tank–that’s how much a fill-up at a penny a gallon less will save you. Driving across town in stop-and-go traffic to save a penny a gallon won’t help you. Check gas prices when you’re running an errand anyway, and if there’s a good price on your brand near where you’re going anyway, fill up then.

15. Dirt and gravel roads can decrease gas mileage by 30 percent.

16. Drive at steady speeds in the city. Stoplights are usually timed very close to the speed limit, so you can catch most of the green lights by driving legally.

17. Use snow tires in the winter; the increased traction improves gas mileage. But in the off months, the deeper tread hurts gas mileage.

18. When you buy tires, radials can improve gas mileage by about 3 percent.

19. Don’t use 4-wheel-drive unless necessary.

And that’s all I’ve got.

Roll your own router with an old PC

Freesco works. Yesterday was D-Day. I brought a copy of Freesco over to Gatermann’s, set it up, and watched it go. Well, at first it didn’t–it got the two Ethernet cards confused. So I switched the cards and it fired up. Absolutely smashing, as they’d say in Britain. I dumped it to his old 1.2-gig Quantum Bigfoot hard drive, and it boots up in about 35 seconds. When living on a hard drive, Freesco wants to dual-boot with MS-DOS. He didn’t have DOS on that drive, so Tom dug out an old Windows 95 boot disk, with which I SYSed the drive. Then I just took the file router.bat that Freesco dumped to the drive and copied it to autoexec.bat. Then I rebooted and we got a laugh.

Starting Windows 95…. Then it briefly displayed the Windows 95 splash screen. Then the splash screen went away. Loading Linux, it said. Ah, Linux comes and kicks Windows aside. We both got a chuckle.

And Tom had a great observation. “The only time I ever have to reboot Linux is when I take the system down to try a different distribution,” he said. That’s about right.

I was talking about what a great use this would be for old, no-longer-useful PCs–as long as it can run Linux, it can be a caching DNS, a router, or something else useful. That means any 386 with 8 MB of RAM is a candidate.

But don’t throw away the 286s yet. Then someone had to one-up me. Dev Teelucksingh, master of DOS utilities, sent me a link: .

What is it? A DOS-based router. System requirements: DOS 5 or higher, 286 CPU, 1 MB RAM. Astounding. So even a 286 can be useful, even in this day and age. Licensed under GPL, so it’s free. No caching DNS, but hey, on a 286 with a meg of RAM and running DOS, whaddya want? And just giving the program a quick look, a hard disk should be optional–the program is 430K zipped, so it should fit on a high-density floppy along with DOS, HIMEM.SYS, and packet drivers for the NICs. Boot it off a 5.25″ 1.2-meg drive just to see what looks you’ll get. 🙂

Come to think of it, I have a 286 with a meg of RAM around here somewhere. Part of me (the insane part, surely) wants to give it a go. The question is, can I get two NICs working in 8-bit slots, since I know that 286 only had one or two 16-bit slots and I think they’re occupied by the disk controller and video card…

Here’s Dev (his site’s definitely worth a look even if you have no interest in IP masquerade–I’ve never seen a better collection of DOS programs):

Been reading your posts regarding IP masquerading and I found two DOS solutions (just waiting to get a ISA networking card to try either of them 😉 )

IProute v1.10 is PC-based router software for networks running the Internet Protocol (IP). It can act as a demand-dial router between your LAN and a PPP or SLIP link, and allow transparent access from your LAN to the Internet using a single IP address through network address translation (NAT). It can also act as a PPP server for dial-in connections, or route between LANs. Other features include routing between multiple ethernet and serial interfaces, packet filtering, RIP, and event and packet logging to a remote syslog daemon. More recent features include proxy ARP, remote management via telnet and ftp, support for RealAudio & RealVideo, a RADIUS client, and a DHCP client. Shareware. (1 hour demo available for download)

Internet Extender

The Internet Extender is a DOS based program designed to function as an Internet Gateway Router that performs Network Address Port Translation. The program must be used in an multi-homed machine, or a machine with two network interface adapters connecting to separate networks. The two possible configurations are: 1.) Connected to the Internet through a Modem 2.) Connected to the Internet through a Network Interface Card

Freeware, (published under GNU license) so source code is also available

Dev Anand Teelucksingh
Interesting DOS programs at
Trinidad and Tobago Computer Society at

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