Monday, February 19, 2024

Various plane-tracking system woes.

According to FlightAware, I've been tracking aircraft via ADS-B signals on the 1090MHz band since about mid-2017.  That's honestly so long ago that I've forgotten about what prompted me to do it (other than having a passing interest in RTL-SDR, a spare 20 bucks, and a Raspberry Pi doing not much else). I've got a picture of my first system, though. A little stubby antenna next to my larger HDTV antenna in my attic.

IMG_20170731_205710

Not much to look at, to be sure, but things progressed slowly but surely from there.  Sometime in 2020 or 2021 I got a new antenna, and the switch made a HUGE difference. You can see me switching the antenna over in the video below.

Not too long after that I started with the Balena ADS-B project, and sometime in 2022 I started pulling in 978MHz UAT signals as well.  It's been fun and a nice outlet for my amateur radio adjacent desires.

But, sometime a few months ago, my reception quality dropped precipitously. I hadn't changed any setup stuff, and there hadn't been any recent upgrades.  The antenna installation on the roof looked ok, too, so the only think left to do was poke around in the attic to check out if something was awry there.  I grabbed a spare laptop and climbed up the ladder to check things out.

Everything looked more or less fine, so I unplugged the USB cable from the Raspberry Pi and plugged it into the laptop (also running dump1090-fa) to see if the laptop fared any better.  Slightly?  But also the USB cable was quite loose when unplugging it from the Raspberry Pi, so I plugged it back into the Pi firmly and went back down into the house, a little dejected.

Suddenly the signal was a whole lot better!  Was it the USB cable all along?  Since everything in the attic was just sort of sitting on a shelf, I decided to fasten the equipment more firmly and get some new USB cables.  Here's the result of my handiwork.

PXL_20240211_194559126

(There's a newer HDTV tuner under all the ADS-B stuff, and the splitter will eventually be hooked up once everything ends up being sorted)

Securing everything and making the signal path look more tidy (as well as getting new USB cables) did absolutely nothing. In fact, it went back from the week of being much better to bad again.

After another week of watching my stats fall, I took another crack at it.  Did something about my laptop setup change the USB receiver?  Looking at both the setups, they were identical.  Was the automatic gain control (even though both the laptop and the Pi did it) the problem?  No.  I dragged the laptop back into the attic again to see if switching the connection back and forth would "fix" the problem.

I had the Pi feeder up on the laptop screen so I could do a before and after comparison, but before I switched the USB receiver over to the laptop I took a moment to tidy up the antenna cables.

My signal was back!

It turns out the antenna cable has been "not great" for a while.  I'm not sure what caused this, but (unfortunately) the other end is bonded to the antenna, so just replacing the cable isn't an option.   Thinking that the problem is in the last ten feet or so and having a lot of slack, I've ordered a new connector and we'll see if that can clear it up. For now, my stats are rising again.

I also wrote a quick script to grab the stats file from the Pi and print it to a log every few minutes.  Maybe I should start a github for this sort of thing.

Life on the IP blacklist.

Executive summary: If you suspect your IP might be on a blacklist, check here.

Over a year ago, I started having trouble logging into my bank.  I could type in my name and password, but I'd get a cryptic message...


The requested URL was rejected. Please consult with your administrator.


Your support ID is: <some random collection of digits>

It was probably one of the more unhelpful messages I've gotten.  The weird part was, it only happened at home.  If I was at work, or at a coffee shop, or on my phone, no problem.  Even with the same computer and no other changes; it would work almost everywhere but my house.  I wasn't doing anything fancy with a VPN or anything, just using what my ISP gave me (though I did buy my own modem, and I'd upgraded that one recently with a newer model from a work buddy).

My wife noticed some other problem with the Barnes and Noble website, but ended up ordering from Amazon instead.  We saw a few other problems with a few other websites, but the bank website was the clearest error (go figure) so I went to talk to the bank support telephone line.

After going through the usual rigmarole (are you sure you're typing the URL correctly, restart browser, clear cache, clear cookies, reboot computer, reboot router, reboot modem, reboot everything, use a different browser, computer, etc) despite a clear reporting of the error message and as complete of a non-technical description as I could give (doing nothing else but changing networks fixes this), I was told they couldn't help me but the problem must be on my end.

I tried the bank e-mail line, which I was hoping could give me better results (I could type everything out and they would read it before contacting me and maybe just maybe there would be a higher up person looking at e-mail), but was told the same thing, and to call back and ask to be connected to the internet services department.  This... got me the same result as before.

I suspected that the IP my ISP assigned my cable modem was on some sort of blacklist, but internet sleuthing didn't help much at the time.  I mostly found spam e-mail blacklists, which wasn't a big help. There were other problems, but none of them were insurmountable and so I just learned to live with it.

Then I was hanging out with a friend and tried Hulu for once, and had the same problem, except now it was complaining about an "Anonymous Proxy".  I found this webpage, with the following note.


  • Commonly, ISPs assign shared IP addresses to its users. Often, such IP addresses get blacklisted, for instance, when any user tries any inappropriate activity or use any banned tool on that IP.
So, if the ISP reassigns the blacklisted IP, the user may get the proxy error when accessing Hulu. The common workaround to the problem is to report the ISP of any possible blacklisted IP and request them to reassign you a whitelisted IP.

This was something I could do something about, but it would take... time.

Anyway, I then had to wait until I had time in order to do something about it.  Eventually I had an afternoon to myself and hopped on the phone to ask my ISP to change my IP address.  I told them the error I was getting from Hulu, and that I thought there was something wrong with my IP address that was on my cable modem.  I was taken through the whole process of rebooting everything yet again (this time I got to reboot my Roku, which was the device that reported the error).  I knew that simply rebooting my modem wouldn't give me a new IP, and I told them this.  There didn't seem to be any answer they could give me.

A neat aside from all this is that I was constantly asked to give phone support folks reviews.  Many of them stressed that the reviews were to reflect how they performed as a customer service person and specifically not if the problem was fixed. Pause, and think about that for a moment.  While it's entirely possible that the problem is insurmountable, or not theirs (the internet is a complicated place), it also sounds like you could be dumb as a bag of hammers but super nice and get great marks; especially if one of the metrics is "how few callers you have to pass up to second line support" (which is probably what I needed).

Anyway, after my twin debacles with phone support from my ISP and Hulu I did some more web sleuthing; this time trying to splice in terms from my error message along with the word "blacklist".  I ended up finding BrightCloud, which provides services to third parties and "Threat Assesment" of incoming IP requests.  This means that your IP security person can install it and presumably not tell anyone what it looks like if a user gets rejected because of a blacklisted IP.  In the case of the bank, it was super obvious, and yet first line support had no idea that's what this error message said.

I'll allow as how maybe this is one of those "long tail" problems that doesn't happen to folks often enough to warrant having a quick solution at hand on the front line, but it seems to be that those kinds of problems get dropped by the front line, rather than passed up to second line, across the board.  Many folks I've told about this would have...

  1. Never thought of the existence of an IP blacklist.
  2. Never pursued this problem long enough with support to get a solution.
How many other problems of this type are out there that people are just living with?  Not just internet problems, but any problems requiring phone support?  The only conclusion is the phone support is broken for all but the most common problems.

Wednesday, November 17, 2010