Category Archives: Networking

Modem maintenance

So, i have been having some trouble with my Nebula line. About a month ago, something odd happened, and my line dropped, only to reconnect at about half the speed that it used to be. I called them, they fix something and the speed improves marginally, but i have had no explanation as to why this happened. If i change nothing, how can the speed drop?

According to their technicians, the line should handshake at 18/2.5 mbit/s, but i’m getting about 10/2 mbit/s. So anyway, i said, okay, the upstream improved to about what they said it should be, and the downstream isn’t that important to me anyway. That ticket was closed.. only to be re-opened a few weeks later, when i started having unexpected packet loss. It’s a copper connection so there’s really no reason to have packet loss, especially in this day and age. Not unheard of though, with bad lines etc, so i called Nebula again.

They’ve made a number of suggestions, such as “faulty wiring” (changed), “faulty modem” (also changed, more on this later), to “a bad copper pair to my apartment from the building phone board”.

So far i’ve ruled out cables. Nothing has changed there, but none the less, i swithced all cables that i could. No change. I changed the modem now, from a 2 year-old Linksys WAG200G, to a Telewell TW-EA501 (provided by B, thanks). So the Telehell connects at about 9/2mbit so the speed is worse still. I’ve now had it in for about a day, and i’m gonna keep testing it, to see if the problem returns.

If it does, then it’s something with the damn line, and they are going to have to do something about it. The speed.. well, i know the modem affects the speed a bit, but how can i get such varying results? All modems have had their firmware updated, and i have no long extension cords for the phone line, nothing like that. If the copper pair is crap, then i guess i’m fucked (and have to wait for the “mandatory” fiber connection no later than 2015).

This has caused unnecessary downtime for my server, Agamemnon. The gods don’t look favorably on this.

General stuff, and the Matkakortti

A new machine was added today, a Sun Netra X1. It’s basically like a weak version of the Netra T1 that i got earlier. I’m not sure what i’ll do with it, but those Sun machines are pretty cool looking, so i couldn’t pass it by.

The specs are basically, a 500 Mhz Ultrasparc IIi, 512 RAM, and two IDE disks. No floppy or CD, and two NIC ports plus a serial interface and two USB ports. It could run something like Sun Solaris 8, 9 or 10, or it could run say, the Debian SPARC port. It would take up a light network task perhaps.

In other news, i’m thinking of ditching Windows 7, because it sucks. I’m serious. The transfer speeds with any drivers that are available, are appalling. I was moving a file and it was doing it at around 2.6 MB/s. Booting to ubuntu, i got speeds between 25 and 40MB/s. How can this be? And in Ubuntu, i don’t even have to install drivers, or think about write caching, or anything else. It just works. So i can’t understand how this shit can be that difficult? I have a modern motherboard, with a modern chipset. The disks are capable of more.

I’m probably replacing the P4 rig inside Agrippa, with the Athlon 64 3700+, simply because i think there’s something wrong with the IDE controller on that P4 board. The two drives in one of the IDE-busses keep disappearing randomly, which makes booting anything from them very challenging.

I’m working on making a server for the intranet, as Agamemnon took a place in the DMZ. The inside server would take care of DHCP allocation, and DNS. There would also be a pf machine (possibly one of the Sun machines?) that would handle traffic coming in and going out from my internal network.

I’m starting in earnest to investingate the Matkakortti system that we use here in Finland. It’s equivalent to the US and Chicago Metrocard system, except that system is primitive, and based on a magstripe and reader, where as Matkakortti uses an RFID chip to send and receive data.

What i’ll start doing now is the following: I’ll collect the numbers of cards and compare them to see if there’s a difference in the two main card types. The types are the personal card, which is bound (and contains) the information of the cardholder, and the non-user-specific card, which is more expensive, but can be transfered between people in a family for instance. The card numbers should contain some information, as it’s a very long string; a lot longer than the amount of cards in circulation.

The card is only used in the capital region. There has been talk of making it Country-Wide, but financial hurdles have so far prevented them from deploying it everywhere. Figures…

Another thing i want to investigate is, getting a device that can tell me if a frequency is transmitting or not. Then,  i could see how long the burst of data is between the reader and the card when you show it to the reader. The next part would be to get a reader, and look at the actual data, i.e. send out 13.xx mhz to the card, and watch what it sends back. It’s probably encrypted, but it can’t be too encrypted, since we are dealing with a very simple, quick system.

Also, i’d like to find out how the busses communicate with some central entity, in order to keep track of what’s on your card. A personal card can be recovered at certain service desks, and they have the exact up to date information on what is on your card. For a fee of 5 euro, to recoup the cost of the card, they’ll give you a clone of your lost/missing/stolen card, and deactivate the old card. This tells me they can do a system wide lock of a certain card number, as well as know the specifics of your card.

The readers themselves have a buffer, because i’ve encountered one beeping constantly and displaying a “Buffer full” message on the screen. The device was locked out and could not be used. Supposedly, the beeping only stopped once the thing was turned off, and then needed to be emptied/reset by a technician. I’ve only seen it once, which leads me to believe that there is a set buffer for a device, and that it perhaps uploads once or twice a day, depending on the line. But how does that work then? It wouldn’t be completey up to date in that case.

The other alternative is that it does send data constantly through some wireless link (the trains are bound to have a link for control purposes, some RF thing), and that the reader had just faulted somehow and not handled the buffer as usual, filling it up with people’s swipes.

It’s an interesting system. As an example, here are the three numbers displayed on the backside of my card:

In the top left edge: 042405535

In the middle: BUSCOM 0523

In the top right corner: F2463001111154998100

If you have a card and want to help me out, send me the info from your card to grelbar ( äet ) grelbar (dot) net.


The company got an offer from a local ISP, Nebula, for a fast DSL connection for our employees.

Now, Nebula is known among hackers as the best ISP in Finland. Not because of their quality of service (which doesn’t always compete with the big players), but for it’s customer support, flexibility, and freedoms they offer their clients. Nebula was founded, and is run by geeks. You can call them on a sunday to report some oddity, and most likely, they’ll start fixing it right away, instead of waiting for the next available business day. Honestly. Also, running servers is not only allowed, but encouraged. No odd blocked ports (like 25 which is blocked by every major player in this country, including Elisa, Sonera and others.), and you can get a static ip for a set sum of 25 euro, no monthly fee.

Shit, you can even buy your own /29 or /27 if you should feel the need. Most ISP do not even offer that at a price for consumers, and that can be said for my previous provider, Saunalahti. They will be losing a long-time customer as of.. well as soon as Nebula connects my new 24/3 ADSL+ Annex M connection, with static IP.

Eat that, fools!

By the way, it’s lucky that my Linksys WAG200G DSL router supports Annex M connections as of the 1.06.6 Firmware update. A good buy, but it’s an old “out of print” model at this point, i think.