Quote from: nanona on November 07, 2017, 07:16:19 AM

Quote from: nanona on November 05, 2017, 01:26:43 PM

The network suffered an instamining attack for the past two hours (10:50-12:40 GMT) done over the mine77 pool. I think I saw something like 350kH/s at work. 50kH/s of which are the genuine permanent miners in that pool, so the attacker used appr. 300kH/s. During these hours we saw blocks 30208 to 30406 which was 198 blocks in 110min or 1.8 blocks/min or an average block time of 33 seconds. The normal rate would have been 36 blocks during that time, therefore 162 blocks (nearly 14,000 IRD) were mined in excess due to the not fast enough difficulty re-target on this blockchain.

I suggest the dev team starts to implement a more up to date diffculty re-target function. In the past Sumokoin (SUMO) and Masari (MSR) suffered the same fate of getting raped by nicehash idiots, i.e. centralized hashrate for hire. Masari then adopted the retargeting from SUMO which stopped these attacks. I consider these attacks equivalent to someone going into a restaurant, eating and then running away while telling the waitress that the invoice will be paid by the next customer.

This is exactly what will happen now since the difficulty is slowly (and delayed) adjusting upwards long after the attack has stopped, which means the genuine 24/7 miners which actually secure the network will mine against a high difficulty (which comes too late), will waste lots of electricity and get very few blocks, i.e. coins. They basically subsidize the coins stolen by the nicehash idiot. Yes, I consider it theft because the nicehash attacker is not willing to mine at the difficulty his hashrate generates. That's why he ran away after a short time and doesn't mine 24/7, knowing exactly that the invoice (difficulty) is presented only after the fact and he can leave it to the other miners.

The difficulty re-target will always be a trailing indicator because it works based on the block times found previously. But it must be such that it can react very quickly on such hashrate attacks and drive difficulty up immediately when the blocks start flying. Once it stops, it must equally quickly adjust difficulty down of course. Other coins have solved this very well and this coin should upgrade as well on a coming HF. After all the block time is the heartbeat of the network and it must be predictable and constant. It is additionally controlling the issuance of the coins (inflation) and this must be fully under control and resilient to such nicehash attacks. Hence why I always recommend that pools do not accept nicehash workers. Nicehash is the exact opposite of a decentralized ledger and currency mined by decentralized miners. It's a centralized service which should be blocked wherever possible.

Quote from: nanona on November 05, 2017, 09:28:04 PM

The network difficulty has slowly ramped up to 20M now, despite the attack being over since more than 8 hours and the global hashrate back down to 50kH/s ever since. This is two times the 10M it had when the attack started. Blocks come in very slow therefore. The last 20 blocks took over 3 hours to mine (almost 3.5 hours), which means the miners are now earning less than one third of the coins they should earn for a couple of days to come until the difficulty will be back down to 10M. They are paying for the nicehash freeloader. If they are unlucky the freeloader will return just when the difficulty is again back to nominal. Rinse repeat.

The pools are certainly not earning more fees due to such incidents. Because the long period of slow blocks and less fees (per hour) now will make up for the short period of more fees (per hour) during the attack. I am therefore puzzled why they would actively invite nicehash attacks by providing a dedicated port just for this centralized service.

Same attack again today through the mine77 pool, from 4:30 to 6:30 GMT, just when the difficulty from the previous attack had come down again to the regular 10M after nearly two days of slow blocks and low rewards for the permanent miners. This time during 2 hours we had blocks 31046 to 31161, which is 115 blocks or nearly 60 blocks/hour and 1 block/minute, instead of the normal 20 blocks/hour and 1 block every 3 minutes. A total surplus of 75 blocks or 6,375 IRD mined at zero additional costs for the attacker, well, the permanent miners are paying for it now and for the next two days as the difficulty is shooting up now. It's already at 13M and increasing and the genuine 35 kH/s on mine77 and the 25 kH/s on the two other pools will now mine for very little rewards.

Thanks for the information. Are devs dealing with this ? It seems urgent and unfair for current miners.