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Once a week, I download a file from the US FCC. I have a bash script with the following.

curl http://wireless.fcc.gov/uls/data/complete/l_amat.zip --remote-name

Every week, the first attempt to run that stalls. The data never flows. The progress message from cURL is working, time is ticking away but data rate is zero.

If I hit ctrl C to stop and then immediately run again, it works perfectly every time.

There seems to be a time period that I can leave it and it will work again first try. I think that time is about ten minutes. If I leave it longer than that, I need to do the start, stop and retry thing again.

This is Ubuntu 18.04 LTS running at Linode. It's only a hobby thing of no real importance but what could cause this? It's the only thing stopping me from fully automating the process that this is a part of.

tetranz
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  • Are you behind some proxy server, that first needs to cache it an then serve it to you from the cache? The upload speed of that server is slow so ~10min delay seems right to get it cached. – Koubas May 19 '20 at 11:27
  • No proxy server. I only need to run my first attempt for a few seconds, stop and restart to make it work. – tetranz May 19 '20 at 11:37
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    Run the first attempt with "curl -v", might give some interesting reading. – Gerard H. Pille May 19 '20 at 11:38
  • Maybe one of your DNS resolvers is not working properly? – Koubas May 19 '20 at 11:39
  • Also, if I run a couple of traceroutes to wireless.fcc.gov, the route is not always the same. – Gerard H. Pille May 19 '20 at 11:46
  • Thanks, I'll look at the traceroute and verbose option. The thing that makes this weird is that it is absolutely consistent. I've been doing it nearly every week for about two years and first time always fails, immediately ctrl c then run again always works. – tetranz May 19 '20 at 15:59
  • I've "solved" it. This is not really an "answer" but I didn't realize that it was using ipv6. That shouldn't be a problem but it works just fine if I force it to ipv4 with -4. I can even run it with -4, it works first time, then try without -4 and it doesn't work, stop, imediately try again without -4 and it works. Maybe something weird with someone's ip6 router or something? – tetranz May 20 '20 at 17:22

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