Thanks , now I understand...

How come you switched to PPS? I had liked your older model, seemed like the payout was higher than PPS pools I tried...

Correct. PPS is very vulnerable method and I don't plan to implement this. Everybody with few Ghash/s can bankrupt operator of PPS based pool in few weeks. I had few attacks to the pool already, so I don't want to open door for another one.

This pool is score based, which is the best known anti-cheating technique with fair payouts. The pool also keep the same rules as original Bitcoin mining (120 block confirmations, invalid blocks, stale shares), because I believe they are good enough. Also people who take mining seriously and don't need cash ASAP probably don't need PPS, because they cut their income for no reason (IMO, pls no flame).

But of course I like there are PPS based pools, because people have freedom of their choice and Bitcoin is about that.

How?

• 1. Take poclbm
• 2. Modify it for checking shares against full difficulty. Don't send full difficulty shares to server. (1-2 lines changed)
• 3. Have a fun
• 4. Few weeks ago - pool closed

There are some modifications possible:

• a) Do this from your single IP. Careful pool admin probably ban you after >500k shares without found block.
• b) Install http proxy in your office/school, in your parents house, ask your friends to install proxy on their computers. You have probably next 10*500k shares to spend.
• c) Install Tor. Next milions of shares.
• d) There many other posibilities like free proxies, buying few zombies etc.

There is no defense against that. All risk is on the pool operator, on the single person. You can block IP ranges of Tor (but many people use Tor with pool already for their good reasons), you can implement blocking http proxies or whatever else. All those defense techniques are only "security by obscurity". With PPS you (as attacker) get paid for all shares except "winning" one, which is even worse than atack on score/share based, where by keeping winning shares you are also slightly cutting your income. This sabotage attack is well known, but with PPS it have yet another dimension of weakness.

Signed up for a bunch of pools and got confused by all the emails, sorry. It was a BTCMine (btcmine.com) email , here is what is said if your interested...

"Due most of miners want score or pps payout model, pool switched to score based payout model.
This model prevent possible loss for cpu miners and protect pool from timing attacks.
All already submitted shares calculated with 1.0 score and will be paid, when pool solve next block.
There is possible some small bugs due this update, please send your reports.

BTCMine Robot"

Attacker does not loss anything, he can pull his >3 Ghash/s rig without _any_ loss for him.


People will be affected by closing the pool. You're right, with share based pool the loss is divided between hundred or thousands of users. Which it also makes less attractive for the attacker, because then his motivation is only fun, not necessary closing the pool, because it's not so easy to do in this way (DoS is more likely).

Anyway I don't want to open discussion about this again. Sabotage attack is well known and described also in some PDFs (I cannot find the source right now, but there is discussion about that on this forum already). I just wanted to tell why I'm not providing PPS model.

I discussed yesterday with Tycho about PPS cheating problems, and completely forgot about this case
There is so much dumb asses,  who want a few "free and easy money".

p.s. every day some funny haKerZ spam my sever with longpolling request's at 30rq/s+ (as I predicted and send some messages about this to m0mchil).
      useless attempts anyway

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