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File 141324529758.jpg - (57.45KB , 300x300 , threadmill.jpg )
1012 No. 1012 hide watch expand quickreply [Reply] [Edit]
what do you think, /tc/?
25 posts and 1 image omitted. Click Reply to view.
>> No. 2354 [Edit]
These sorts of counterintuitive puzzles are great at forcing you to understand physics. Another one I came across which I'm still trying to puzzle out:

Which manifests in the "sailing downwind faster than the wind" thing demonstrated by Blackbird:
>> No. 2355 [Edit]
It won't, because the wings will crash into the treadmill.
>> No. 2356 [Edit]
Ok after some thinking I think I understand this now. There are two main questions to address: why the top wheel counterintuitively spins anti-clockwise despite a force directed from left to right, and why the entire contraption moves to the right faster than the ruler.

The key thing to first observe is that the bottom two wheels aren't uniform in radius. They have an inner and an outer radius (due to the nature of the cotton spoon) which is perhaps more clearly seen in this diagram [1]. This already gives a hint of why it can move to the right faster than the applied force, due to a "gear ratio" effect. However, while the calculations are useful for verifying this quantitatively, it still doesn't give a good intuitive answer, nor does it explain why the top wheel spins anti-clockwise.

The best answer I've seen is courtesy of a post on reddit [2] which I'll quote here for completeness

> For the car to move right, the little wheels must turn clockwise, and the big wheel must turn counter-clockwise. This would give you the impression that the ruler must go left to turn the wheel counter-clockwise. That is true, relative to the car.

>Looking at the construction, one immediately suspects that the size of the wheels is somehow involved. But that isn't quite it. Actually, it is because the big wheel touches the ground wheels on an axle, not the part of the wheel that touches the ground. This creates a situation where the speed the outside of the little wheels move faster (in terms of linear velocity) than the outside of the big wheel.

>So, shifting out point of view to the car, you have a wheel to the ruler, and wheels to the ground, and the wheels are geared such that both surfaces move in the same direction, but the ground moves faster, relative to the car

>So imagine now that the car has a motor, and the ruler is just resting on top. As the car moves right, the ground moves left relative to the car. The ruler moves left relative to the car, but slower than the ground. Th
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>> No. 2375 [Edit]
This explanation also naturally extends to the "downwind faster than the wind" vehicle Blackbird. It's the same principle, where you derive energy from the relative difference in speed between the air (the ruler) and the ground. There should be no doubt that this is possible in the simple gear example, or you can also think of a lever if you like a static equivalent of how you can increase speed (at the expense of decreased force).

But with a propellor in the vehicle, now the linkage becomes a bit more subtle. You have to consider the propellor not just as a flat disk, but consider the actual blades of the propellor itself which take a helical path. Then the issue of gear ratio is manifested between the forward motion of the vehicle and pitch of the propellor. The fact that the wheels turn the propellor in the direction against the wind, means that vehicle can travel faster than the wind (with respect to the ground) while still maintaining the property that a single propellor blade – importantly accounting for the helical path – is traveling slower than the air surrounding it. The parallels to the simple 3-wheel cart should be clear.

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2330 No. 2330 hide watch expand quickreply [Reply] [Edit]
Let's talk about web hosting and what that involves. I'm interested in diy solutions, especially for security. Cloudflare is now ubiquitous, but is it really necessary, or are there things web masters can do to protect their website themself?

I've seen some onion sites which have a password prompt to access. A simple pop-up that requests the user type in a given username and password. Is a simple solution like that good enough to defend against ddos attack?
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>> No. 2335 [Edit]
File siff.pdf - (200.01KB )

No, not unless you fundamentally redesign the architecture of the internet. See linked paper for how to prevent ddos by redesigning connections using a capabilities-based security model.
Even if you have the best in class hardware for processing inbound packets, you're still bottlenecked by the link between you and your ISP. And most ISPs are not prepared to handle a huge spike in traffic and will blackhole you until the traffic decreases.

If you want to serve live-content immune to DDOS, at a fundamental level you need to work around the single point of failure. Either you add enough redundancy or indirection through geo-distributed servers (á la cloudflare), or you can try to get fancy with some sort of p2p-esque scheme. But I'm less familiar with the p2p solutions in this area, and you're basically trading off ease of content updates (trivial if a single server, hard when needing to deal with distributed systems that you don't even own) with robustness against ddos attack.
>> No. 2336 [Edit]
>And a static IP
You can work around this with a dyndns type setup. And in practice your assigned ip usually remains fixed unless your reboot the modem so it shouldn't be too much of a hassle. Definitely not a commercial-grade solution though.
>> No. 2337 [Edit]
>See linked paper
The solution proposed in this article requires the involvement of ISPs, at least to update routers. So is a purely software-based solution that would put the computing burden of authentication on users impossible because of the physical infrastructure of the internet?

Could the address of a website not be obfuscated in some way, and periodically changed, so that the only way to find it and send packets to it, would be for the client to run a program that solves a complicated math problem or something?
>> No. 2338 [Edit]
File savage-traceback-sigcomm00.pdf - (124.17KB )

> requires the involvement of ISPs, at least to update routers
Yeah hence why I mentioned it requires basically redesigning the architecture of the internet.
>So is a purely software-based solution
I think what you mean is whether there exists a solution that can be implemented on top of the existing routing architecture, involving only changes to the endpoints? If so, my intuition is that this is not possible because by design the way routing works on the Internet is that a client can send packets to an server without that server having prior knowledge that the client exists. And in fact, since a client can spoof the source IP the server fundamentally _can't_ be sure of the client's identity. (Note: good ISPs will have ingress IP checks and nullroute spoofed packets, but all it takes is one non-conforming ISP to allow for this).

You might be interested in the attached paper which shows that even solving a strictly simpler problem: reconstructing the path that a packet takes throughout the network (thereby preventing spoofed source IPs) is still very difficult. The authors use a very elegant packet tagging scheme and go to great efforts to maintain compatibility with the existing IP packet formats. But the fundamental limitation is that it requires a significant fraction of ISPs to adopt it, and given that packet routing is mostly done in hardware these days it will require huge costs to replace all this hardware as well. (More generally, you'll see this chicken and egg situation is the single biggest issue with bringing academic research in networking security into practice. They usually only work if there's mass adoption, but no one will be the first to adopt it due to costs).

>Could the address of a website not be obfuscated in some way, and periodically changed, so that the only way to find it and send packets to it, would be for the client to run a program that solves a complicated math problem or something?

Once you deobfuscate it on one client, you can share that deobfuscated address between all clients. The asymme
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1200 No. 1200 hide watch expand quickreply [Reply] [Edit]
intel vs amd which processor is best?
6 posts and 2 images omitted. Click Reply to view.
>> No. 1215 [Edit]
>I've never once in my life heard someone refer to a GPU or APU as just a "processor".

which clearly means nobody elsewhere in the world has or ever will, as you've been everywhere in the world, all the same time, and are the authoritative expert on the subject.

>You knew damn well what he was talking about.

I never said I didn't.

>You were just playing devil's advocate for a purpose I'm not entirely clear of. To appear "knowledgeable" by making the distinction, maybe?
Perhaps I'm just arguing for the sake of arguing. On the internet. Because I have absolutely nothing more productive to do at this very moment.
And arguments are the only type of conversation I am capable of doing with another person.
>> No. 1216 [Edit]
I'll give you credit for the honesty.
>> No. 1855 [Edit]
Honestly I wouldn't notice the difference if everything worked right but subjectively speaking I choose Intel forever, just because I always had issues/subpar performance with AMD/ATI back in the day.
Also their hurr durr epyk gayming branding is fucking embarrassing. I'd never put something called Bulldozer or Ryzen in my computer.
>> No. 2300 [Edit]
Interesting how quickly things change. Intel has been sleeping at the wheel for the past two years with their "tick-tock" being more of a "tick-tick-tick". Of course Apple has hit it out of the park with their arm-based processor. One might optimistically hope this could lead to the resurgence of different isas (maybe riscv?) but we're probably more realistically going to see arm-based processors start shaving off marketshare from x64 ones. Amazon already has graviton as part of their ec2 lineup, and hopefully the momentum from apple's processor transition will lead to better tooling for cross compilations and platform agnostic primitives.

File 161580064478.jpg - (75.71KB , 1280x960 , IDK.jpg )
2209 No. 2209 hide watch expand quickreply [Reply] [Edit]
tfw I'm posting from an e90 communicator. idk how to update internet (I tried everyhing, trust me) and this chan is one of the few sites which my phone is able to surf.
5 posts omitted. Click Reply to view.
>> No. 2222 [Edit]
OP here again: I'm a dumb person with many projects but few results and trying to update this shit was a funny hobby in the quarantine, however my results are still zero. Any advice? I tried also to install DOSBox but it doesn't work
>> No. 2223 [Edit]
Get a better machine.
>> No. 2224 [Edit]
Lmao like? Old computers just for remaining in nostalgic vibes?
>> No. 2299 [Edit]
Write a proxy to do the HTTPS negotiation and serve back old school HTML w/images, If you do this right you should be able to navigate to most websites and get an experience at least as good as lynx + images.

File 141335966799.png - (45.42KB , 590x340 , OS_logos.png )
1115 No. 1115 hide watch expand quickreply [Reply] [Edit]
What is your preferred operating system and why? If you use linux also mention the name of the distro.
10 posts omitted. Click Reply to view.
>> No. 1180 [Edit]
Only 1 of the games I regularly play are linux compatible and I'm not interested in Super Tux Kart or wasting an hour configuring wine to have the game run at 15 frames per second.
>> No. 1182 [Edit]
Debian stable, nowadays. I used to use Arch, but systemd and various other shit came along with a steady downturn in general, so I jumped ship to one of the only remaining (at the time) options in Debian. Howewer, a few months after that, Debian made the decision to eventually switch to systemd as well, so I'm not sure where to run once the current stable release becomes obsolete.
>> No. 1190 [Edit]
Realistically you don't encounter many OS level bugs these days unless you're doing something weird, yes.
I have an idealized image from what I've heard of live-hackable Lisp and Smalltalk machines of a system where the source for everything is easy to bring up and understand and modify. Obviously not even OpenBSD fits that bill, anything that simple would be a toy OS unfit for normal use. But it's nice to daydream about, I suppose.
>> No. 2279 [Edit]
File 161973280122.png - (12.28KB , 400x400 , d9fa905af1a22c93eab503a5a760a262.png )
This is a really interesting project. I wonder why it hasn't caught on more.
>Like other device driver interfaces used in Operating Systems today, UDI defines an architecture and a set of APIs for use between the driver and the surrounding system. This allows drivers and OSes to be developed independently. UDI goes a step further and provides APIs that are OS-neutral and platform-neutral, allowing multiple OSes and platforms to use the exact same driver.

File 151772797413.png - (95.00KB , 1024x512 , Ways-To-Browse-The-Internet-Privately.png )
1641 No. 1641 hide watch expand quickreply [Reply] [Edit]
So I got my first copyright notice from my ISP today, and it warned this was my second infraction. Checked and saw two other emails I never noticed from them. So now I think it's about time I get on a VPN, as the peer blocker I've been using till now seems worthless.
Can you guys recommend any? I've tried tunnel bear and with their free versions and thought was pretty decent and it allows torrenting. Can you guys recommend any others that wont break the bank, or steal/sell my info?
4 posts omitted. Click Reply to view.
>> No. 2241 [Edit]
What's the difference between that and 2-clause BSD?
>> No. 2242 [Edit]
The 2 clause BSD has no copyleft. Derivative works or even direct copies don't have to include the part of the license which allows for free usage(which isn't clearly defined in the 2 clause BSD). The only thing you have to include is the attribution to the original writer(copyright notice), the conditions, and the warranty, but not the part which lets you do whatever you want to it within some parameters.

This license also doesn't require the name of any copyright holder.

Post edited on 2nd Apr 2021, 3:22pm
>> No. 2243 [Edit]
>don't have to include the part of the license which allows for free usage
To clarify by free you mean libre or gratis? The 2-BSD states

> Redistribution and use in source and binary forms, with or without modification
which seems to cover the libre part for source distributions.

If you mean gratis, then your license mentions "and/or sell copies of the Software" and allows binary distribution, which would prevent that.
>> No. 2244 [Edit]
No, I don't mean gratis. Free as defined as
>deal in the Software without limitation the rights to use, copy, modify, merge, publish, distribute, and/or sell
Somebody could sell their version for money, but the person who bought it would be able to do all of the above with their copy after buying it. Binary distributions can still be copied and sold. Somebody could also de-compile binary software and/or otherwise modify it in some way.

The bsd license does not require this part
>Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
To be included in derivatives and copies of the software. You only have to leave Copyright <YEAR> <COPYRIGHT HOLDER>, the list, and the warranty.

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968 No. 968 hide watch expand quickreply [Reply] [Edit]

This kind of blew my mind, the fact that something we built is out so far, even if it's just a probe from the 70's. I know it's slightly old news, but considering how long Voyager 1's been out there I don't think a week makes much of a difference.
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>> No. 1902 [Edit]
File 157072925648.jpg - (111.74KB , 1024x615 , article-0-11EF84AB000005DC-804_1024x615_large.jpg )
If they are
> in another super-cluster
we will never know

> in another galaxy
we won't know for a long long looong time from now and it's probably irrelevant for us today

> in our galaxy and we detect them in the near future
we are totally fucked, as their first radio signals will reach us thousand years after they have broadcasted them, meaning they have a technological lead of their distance divided by lightspeed minus the few years we use radio signals

> in our galaxy and they detect us first
things will be interesting, as this is the only scenario contact to aliens could be as it is depicted in media with the slight difference that we are actually the far superior civilication

> in our galaxy and we receive their first radio signals from a distance that, devided by lightspeed, is approximately the time we use radio signals ourselves
prepare for interstellar war!
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>> No. 1903 [Edit]
>> No. 2206 [Edit]
File 161368218365.png - (505.26KB , 1280x720 , Screenshot_2021-02-19 NASA Live Official Stream of.png )
Perseverance have just successfully landed in Mars.
>> No. 2207 [Edit]
It's a statistical impossibility. Not just a little one like how it's statistically impossible that you will win the lottery, bigger than that. Much, much bigger. The chances are something like 1 in 10^100

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2196 No. 2196 hide watch quickreply [Reply] [Edit]
some of the heyuris are building a new imageboard from scratch

what are good features to include?
>> No. 2197 [Edit]
They're Ruskies, so I don't care.
>> No. 2198 [Edit]
An imageboard doesn't need "features." Tinyboard/Vichan basically nailed it. The edit feature available on TC is perhaps the only real improvement that upstream tinyboard is missing.
>> No. 2204 [Edit]
All you need is text + file upload. Other stuff is bloat that you can tack on later.
In regards to coding one, HTML5+CSS has actually helped quite nicely. Use custom HTML tags and CSS selectors and things will be much easier.
>> No. 2205 [Edit]
Gurochan is back and it's being hosted or something like that by the same Russians as heyuri, kolyma network. I found this cease and desist letter they sent to "guroboard", since kolyma apparently now owns the tradmark gurochan. Don't know if this is real, but it's weird.


Oh, apparently it's real. Imagine if tohno trademarked tohnochan

Post edited on 13th Feb 2021, 11:54am

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418 No. 418 hide watch expand quickreply [Reply] [Edit] [Last 50 posts]
Let's turn this thread into a browser war!
76 posts and 11 images omitted. Click Reply to view.
>> No. 2200 [Edit]
Far too much of the stuff I need sporadically requires js for me to disable it automatically. I used to have it disabled, and once had to wait 6 hours to make a financial transaction because some security authorization component on a website needed it and that not working tripped a wire or something.
>> No. 2201 [Edit]
Firefox ESR has been pretty bad for a long time now, but I'd still rather use it than Chromium. One thing that concerns me about switching to one of the forks is whether they get timely security updates.
For downloading large files, there's megadl, which is part of Megatools.
I do. Disabling JS breaks many websites, which is a pain. >>/ot/33997 and >>/ot/37266 have been pretty useful, even though some functionality is still missing or partially broken with them. The public Invidious instances in particular tend to be somewhat flaky, which is why I hesitate to link people to them.
Couldn't you disable it for general web browsing and only enable it for financial stuff? You could set up separate browser profiles for this.
>> No. 2202 [Edit]
I use pale moon and switching pale moon profiles is a pain and requires restarting the browser or screwing around in ways that break its interaction with other apps.

Post edited on 7th Feb 2021, 9:45pm
>> No. 2203 [Edit]
Cool I didn't know about teddit. There's also "" which they still seem to keep alive: it preserves the older layout and works mostly fine with JS disabled. Although they've been caught doing shady stuff before [1] so I should probably switch to that.

>Couldn't you disable it for general web browsing and only enable it for financial stuff
Not him but I think he was saying that he didn't even know that the site required JS to avoid tripping the fraud detector or whatever, so he didn't think to enable it. I've noticed this a lot – sites just break in random ways, and if I hadn't used them before disabling JS then I wouldn't even have realized that some dropdown or feature was supposed to exist. It'd be nice if all sites at least supported the noscript tag to let you know that some features are missing.


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2173 No. 2173 hide watch quickreply [Reply] [Edit]
What are your thoughts on alternative web protocols like Gopher and Gemini?
We're living in the dark ages where modern webshites are obsfucated behind multiple scripts and horrible web designing.
>> No. 2174 [Edit]
My thought is that they have low adoption rates, which means standards that advance at the pace of a dead snail. People fill their sites with slow, pointless/malicious scripts and bad design because they can. People can also choose not to do those things. "Quality" via stringent restriction is unecessary and misguided.
>> No. 2175 [Edit]
I've tried gopher before, and it really does all it needs to (there's even an imageboard available, 1436chan, gopher://
I like how it forces everything to be usable be text-only browsers, text being the universal interface.
Making a gopherhole is also fun because it's so easy. It is what the web should be.
If Gemini is pretty much that but in encrypted, then I'd probably be on board as well, but I haven't tried it yet.
>> No. 2183 [Edit]
I really like Gemini. I believe Gemini has some kind of scalability issue however so it could never become a replacement for HTTP. Nonetheless, I intend to use it myself at some point. I do like the idea of forcibly keeping things simple.
>> No. 2385 [Edit]
It's more an issue of content, not protocol, so I don't think alternative protocols will be that useful to solving this. That is, you can choose to make plain-text no-js sites served over http but not many people do so nowadays. Although I guess the giants are trying to stamp out plain http in favor of http over tls which seems pretty pointless for most read-only content.

File 160135249366.jpg - (476.33KB , 509x2195 , Paradigm.jpg )
2064 No. 2064 hide watch quickreply [Reply] [Edit]
... .
>> No. 2065 [Edit]
Care to elaborate? Because the first paragraph of your image is utter nonsense.
>> No. 2066 [Edit]
(for some reason can't edit, so apologies for double post).
Besides the conclusions that don't follow from the previous statements, you also have patently false statements such as "time is space" (while they're linked, sure, they're not interchangeable as clearly seen from the fact that the minkowski metric has a different sign for the time dimension than it does for space).
This seems more like the work of a crank than something substantive.
>> No. 2067 [Edit]
It helps to enter a password manually, the ones given tend to change on their own.
>> No. 2068 [Edit]
I think it's because I have cookies set to expire pretty aggressively, which invalidates the default generated password. I should probably write a userscript or something to automatically set the "postpassword" cookie to a fixed secret value.

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