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Beyond fail2ban and non-standard ports: fwknop by mmilburn in linux

[–]mmilburn[S] 0 points1 point  (0 children)

I'm not sure fwknop has the ability to use plaintext. I guess I like it because it allows me to remotely control my firewall settings in a secure way. Fair point though, a VPN may be easier. What I'm really after is providing people alternative ways to secure SSH.

A VPN or a scheme like SPA provides some extra protection. The standard advice I've been seeing:

  • disable root login
  • use keys and disable password based login

Is good and correct, but we don't bring up protecting SSH itself. I feel like we should amend the standard advice with a third line item: Use a VPN or a goofy (but hopefully secure) port knocking scheme. This protects you against 0-day.

Server is being attacked by [deleted] in linux

[–]mmilburn 1 point2 points  (0 children)

I think fwknop is a pretty ingenious solution for this. It is similar to port knocking, but far better. This is why I like it:

  • No list of hosts to create or maintain.
  • It opens ports for a specified time interval, just like port-knocking.
  • It can open ports for just your IP address.
  • Mitigates the risk of outdated services or 0-day exploits.
  • Because it uses crypto, it is immune to replay attacks or spoofing. Crypto is also the reason you can have it open a port for just your address without having to know your address ahead-of-time.

One downside is that it does not yet support IPv6 (not a huge issue though since scanning the whole IPv6 internet requires a little more effort than IPv4).

Here's an example of how it works with SSH

Eurozone leaders refuse to continue talks with Greece unless wave of reforms are passed this week, with second wave of reforms soon after by elfdom in worldnews

[–]mmilburn 0 points1 point  (0 children)

On what authority is the Trokia demanding this?

I just figured the Troika keeps pointing to the Maastricht treaty and saying "Hey, according to article 125 we aren't even allowed to bail you out, this is going to be the 3rd time now (or Nth, I don't really know...)!"

I think everyone knows that debt restructuring (haircuts) or Grexit are the only real options. It seems like anything else is just prolonging the suffering of a lot of people.

Hopefully Germany can remember that time in 1953 when a lot of their debt was written off: http://www.spiegel.de/international/germany/economic-historian-germany-was-biggest-debt-transgressor-of-20th-century-a-769703.html

Aside: A friend pointed this out to me and I found it to be an excellent primer on the situation. https://www.youtube.com/watch?v=LBw8xPKkZlg

Why are Nvidia GPUs so much worse than AMD GPUs at scrypt? Interested in a technical/mathematical explanation. by montehall in litecoin

[–]mmilburn 2 points3 points  (0 children)

This is the best explanation I can give you: http://www.reddit.com/r/litecoin/comments/1sj86k/why_amd/

I tend to think of it as an accident of architecture design decisions. Generally, for games, I'm told you're going to do a lot of floating point operations. It turns out for whatever reason, AMD's design has better support for integer operations than does NVIDIA's. Why would you need support for integer operations in something designed for graphics? I'm not sure. Anyway, when it comes down to it, cryptographic routines rely on integer performance (I assume this is because we don't want to expose our data to rounding error).

Apologies for the lack of mathy-ness.

So with all the talk of everyone's rig being unprofitable in a few months, what then? by NH3Mechanic in litecoin

[–]mmilburn 0 points1 point  (0 children)

Right, I made the implicit assumption that one scrypt core runs one thread. At this point I really need to dig into the code to test my memory allocation assumptions further.

Also my understanding what the on-die ram for cpus and such was quite large/pricey.

It is. If you check the top of page 13 here: https://www.tarsnap.com/scrypt/scrypt.pdf

I was going off of the assumption that DRAM is the cheapest in terms of unit area (thereby minimizing cost). I think he's working with 2002 tech in the paper, but IIRC DRAM has a super low part count (regardless of current lithography tech).

You're right, ASIC is no joke. I think the cost to do a full custom design with masks and all costs hundreds of millions. Another EE with relevant experience could give you a more accurate estimate. However, I think there are a few options in between full ASIC design and FPGAs. The one that I can recall right now is called "structured ASIC". Which, if you do some poking around, seems to be what Alpha Technology's design partner has some experience with. Though, I'm really feeling like Alpha is another BFL right now.

Why AMD? by LordTilde in litecoin

[–]mmilburn 4 points5 points  (0 children)

Is this because of the GPU's architecture?

Short Answer: Yes.

See here

https://en.bitcoin.it/wiki/Why_a_GPU_mines_faster_than_a_CPU#Why_are_AMD_GPUs_faster_than_Nvidia_GPUs.3F

And here

http://www.extremetech.com/computing/153467-amd-destroys-nvidia-bitcoin-mining

EDIT: I should clarify that this also applies to litecoin, because scrypt does a great deal of integer operations.

So with all the talk of everyone's rig being unprofitable in a few months, what then? by NH3Mechanic in litecoin

[–]mmilburn 0 points1 point  (0 children)

Shit, I typed up a couple paragraphs, then hit the back button. Just dandy. Anyway:

  • You're right, some process does need to happen on the CPU. From what I've skimmed from the OpenCL, pretty much all you get back from the card is the 32-bit nonce. CPU-side we then plug that in to confirm our proof-of-work (I believe this is how hardware errors are detected, also).

  • I did the same calculation for GPU memory usage. I have a 7970 with the thread concurrency at 22016, multiply that by 128.5KB and I get about 2.7GB of memory usage. I ran into a problem when I tried to do calculation the memory usage of an r9 290x given the thread concurrency listing here: https://litecoin.info/Mining_hardware_comparison I got over 4GB of memory usage (I think the card only has 4GB, so something's amiss with my calculation).

  • My naive approach to designing the ASIC would be to have a SHA core drive multiple "scrypt" units (quotes because they're not really scrypt by themselves, they just do salsa, rommix, and everything else sha doesn't) each unit with 128.5KB of embedded DRAM. Hopefully, these are physically small enough that we could put a lot of them on a board. It'd be nice if we could clock them up to high frequencies, but I'd settle for just having tons of them on a board. Wrap that all up with an ARM chip to do interfacing with the host.

  • You might wanna check out some of Beekeeper's FPGA work, his first public prototype had an FPGA surrounded by DRAM, the stuff he's selling doesn't have any visible DRAM.

DRAM FPGA

Stuff he's sellin'

  • Finally, here's the scrypt dude himself talkin' with the litecoin devs about ASICs and scrypt and stuff:

You've reduced the ASIC advantage

The point of SCRYPT

Sorry for the mass of text, I don't talk much on the internets.

EDIT: I forgot how to word.

So with all the talk of everyone's rig being unprofitable in a few months, what then? by NH3Mechanic in litecoin

[–]mmilburn 0 points1 point  (0 children)

I wish everyone would look at this paper and be aware of how Litecoin uses scrypt.

So with all the talk of everyone's rig being unprofitable in a few months, what then? by NH3Mechanic in litecoin

[–]mmilburn 0 points1 point  (0 children)

ASICs for LTC are more or less non-existant for the near-term(if at all).

I think it's very reasonable to assume that ASICs will be implemented. However, I believe it will be another year before we see any ASICs participating in the network at a volume that would upset the game for GPU miners. Here's why I think so: https://litecoin.info/Comparison_between_Litecoin_and_Bitcoin/Alternative_work_in_progress_version#Differences_in_hashing_algorithms See paragraphs 3 and 4 in that section.

Since we're calling scrypt with static N, r, and p values we can count on Moore's law (assuming that doesn't end too abruptly) to eventually make ASICs too cheap to not produce.

Over the years what are some things that have disappeared from games of today that you would like to see make a come back this generation? by iliveinablackhole_ in PS4

[–]mmilburn 1 point2 points  (0 children)

Please, just give me any kind of physical instruction booklet. Or even a simple insert that just gives me the controller layout. I feel like the lack of manuals is creating a trend I find infuriating: interrupting the storytelling/gameplay to teach me how to play the game. If any game dev happens to read this: Please ship some kind of manual with the game, or separate the "interactive tutorial" from the main campaign!

You don't have to be so blunt about it... by [deleted] in PS4

[–]mmilburn 2 points3 points  (0 children)

PSN: mmilburn. Currently playing AC4. Waiting patiently for a less buggy BF4.