Random, RDP hangs, SfB, Yggdrasil, Zstd, Y2020, WiFI 6, CS
Had to change my TRNG server to use PRNG instead. Some users were requesting so much random data, that the hardware TRNG generation performance got exceeded. Currently code is using PRNG which is constantly updated by TRNG updated pool + urandom + bunch of other sources updating third pool which is also automatically updated regularly.
Some initial research based on one Enterprise service bus (ESB) solution utilizing RabbitMQ @ Official RabbitMQ @ Wikipedia. After the quick assessment and pre-study, I said that no problem. I'll get it done, if and when required.
Bit more details about the so annoying RDP hanging, what's required to repeat the situation:
The trick with RDP issues requires specific kind of environment:
1) RA messages causing assigning privacy address to server
2) Firewall which filters non-authorized addresses
3) Static address configured for the server
4) Remote desktop connection using the static address
5) UDP mode enabled
When all of these are combined together it seems that the RDP probably tries to use the default privacy address for UDP traffic and it causes it to hang. If, the firewall, or the privacy addressing ÌPv6 or RDP UDP mode is disabled. Then it works again.
I didn't bother to start network packet capturing, but I tried the things above, and each of those resolved the issue.
I think it would be nice, if the RA / privacy addressing would be disabled, when you configure a static manual address for a server. But it just doesn't seem to work that way with Windows Server 2019.
Unfortunately the combination above is default config with UpCloud service provider and it took quite a while to figure out exactly what settings need to be configured and how to make the configuration to persist over system reboots.
Another IPv6 issue is with Skype for Business. I'm using he.net IPv6 6in4 tunneling and it seems likely that Microsoft is blocking traffic from 2001:470::/32. Because SfB client is badly coded it hangs indefinitely during the login. Again, disabling IPv6 or preferring IPv4 over IPv6 fixes the issue.
Yggdrasil. Yet another interesting network in network solution. Slightly reminds me from Hamachi @ Wikipedia and similar solutions. But it's in early stages. Just checked concept and FAQ and that's it. I would probably describe it with terms: routed, f2f, mesh, VPN, encrypted, network.
Classic Microsoft: Windows Update seriously breaks specific environments. This is what's happening constantly. Topic which could be discussed over and over monthly. But I guess it's hopeless. There's the only right way forward, don't touch Microsoft products.
Installed and tested Zstandard compression @ Wikipedia with zstd @ Ubuntu package and Python PyPi pip zstandard @ PyPi library. Really nice. I guess that's going to be the default compression option I'm using in the future. Sometimes using xz (LZMA @ Wikipedia) if extra tight compression is required, and not minding the huge CPU / memory requirements during compression and decompression. When archiving data tight compression is good. Because it's highly likely that the archive won't be extracted / accessed even yearly. Yet for more often happening data compression, decompression especially when data is quite predictable the custom dictionary compression is just amazing feature.
Year 2020 and cash registers in Poland failed due to Y2020 bug and some Metro trains in Germany stopped running, etc. Interestingly there's no Wikipedia page dedicated for these problems.
Some comments in Wi-Fi 6 (802.11ax) @ Wikipedia discussions made me laugh. Are they just trolling or maybe they're being serious? Who knows. Quote: "In the interest of efficiency, we should probably also truncate year to fewer digits. Perhaps 2. Since we're in the first quarter of a new century, this won't cause an issue for a long time." - Probably trolling. - Wi-Fi 6 (6E) brings support for 6 GHz band (5 cm), which is really nice.
Really nice post: Computer Science from the Bottom Up. Naturally nothing new, but a good read for every wanna be nerd.