Ethereum Gas Reprice Hard Fork Was A Success

Posted on October 21, 2016 by bok

Originally posted Oct 19 2016, updated 02:49 Oct 21 2016 UTC.

Table of contents

Summary

The Gas Reprice hard fork successfully stopped all the previous attacks since the start of Devcon2.

Update 14:26 Oct 19 2016 UTC – The attacker is now conducting a new set of smaller impact attacks using another an underpriced EXP opcode and a BALANCE operation that need some cache improvements – see the updated section at the bottom of this page to see the impact on the block processing. The next planned hard fork will address these new attack vectors – see ATTENTION MINERS: Recommending miners lower the gas limit target to 2 million. What a dynamic and responsive Ethereum ecosystem this is!

Update 02:49 Oct 19 2016 UTC – The attacks have now ceased, at least temporarily. The attacker may have given up as the latest attacks do not have much impact on the running of the network.

And the attacker’s accounts and transactions has ?accidentally? revealed that they pool mined with EthPool and DwarfPool. These pool miners would have recorded the IP address(es) of the attacker’s miners. Read all about it in next exciting blog post Ethereum Network Attacker’s IP Address Is Traceable.

The Attacks

The Ethereum blockchain has been undergoing a attack since the start of the Devcon2 conference a few weeks ago (beginning Sep 19 2016).

The first attack started on block 2,283,416 at 01:04:56 Sep 19 Shanghai time and targeted the go-ethereum geth clients, causing a memory error and shutting down these nodes across the network. Luckily the Ethereum network has separately implemented node clients written in Rust (Parity) and Java (EthereumJ) – these clients did not suffer from the same memory bug and kept the network up and running. The Ethereum developers in Shanghai had to get up early before the start of the conference and shortly after released a version of geth with the memory bug fixed. This ended up delaying the start of the conference by half an hour.

My 125 Mhs solo miner stopped working for the week while I was in Shanghai as I had not set up a VPN connection to my node due to security reasons.

Soon after the first attack, the attacker then regularly sent spam transactions (see here and here) to slow down the Ethereum network. Using cheaply priced opcodes (Ethereum Virtual Machine instruction codes), the attacker sent transactions that caused heavy computational and disk input/output loads on the Ethereum nodes. This was later followed by spam transactions that created many empty accounts on the blockchain, causing a “state-bloat” on the blockchain.

Worst affected users seem to be those trying to run a full sync of the Ethereum blockchain on machines with limited memory and running on a hard disk drive (HDD) instead of a solid state drive (SSD). See Is something wrong with the network right now?, sync isn’t working for 0.8.5 been trying for days and 5th time downloading Blockchain 15 days for example.

Non-spam transactions were failing as quite a number of mining pools decided not to process transactions as these would slow down their mining node operations, and the non-spam transactions were getting lost in the ether.

The Hard Forks

The Ethereum Foundation announced two hard forks to stop the spam transaction attacks. As listed in the previous link, you have to install the latest Ethereum node clients containing the hard fork code – geth 1.4.18, Parity 1.3.8, EthereumJ 1.3.6 and Ethereum Wallet 0.8.6 (remember never to trust links to the node clients from unofficial sites). If you have run an earlier version of the node client after the first Gas Repricing hard fork (see below), you will have to re-sync your blockchain data from scratch.

The First Hard Fork – Gas Repricing

The first EIP 150 Long-term gas cost changes for IO-heavy operations to mitigate transaction spam attacks hard fork successfully activated at block 2,463,000 at Oct-18-2016 01:19:31 PM +UTC to reprice the gas for some of the opcodes. This raises the cost for the attacker to send their spam transactions.

The Attacks Have Stopped

The attackers transactions started failing (source) immediately after the hard fork. This account spend 9 – 3.899521491 = 5.100478509 ethers (~ USD 64.10) to send 1,183 spam transactions to the network.

The Gas Limit

The gasLimit represents the total amount of gas for the computation and storage that can be spent within each block (14 seconds average block time). This gasLimit is a figure that is voted on by the miners.

You can see the Gas Limit chart increasing on the bottom right of the chart below from https://ethstats.net/ around 7+ hours after the hard fork:
screen-shot-2016-10-19-at-07-45-35

Following are some gasLimit statistics. The gasLimit was around 4.7 million before the attack. As advised by the Ethereum Foundation, miners voted to reduce the gasLimit to 1.5 million during the attack to limit the damage by the spam transactions, and this was reduced further to 0.5 million at the later stages of the attack. You can now see it rising to 2.5 million:

function checkAverageGasLimitEvery1000Blocks(lookback) {
    var gasLimit = new BigNumber(0);
    var i;
    var currentBlockNumber = eth.blockNumber - lookback;
    for (i = -10000; i < 0; i++) { 
        var blockNumber = currentBlockNumber + i; 
        gasLimit = gasLimit.plus(eth.getBlock(blockNumber).gasLimit); 
        if ((i % 1000) == 0 && i != -10000) { 
            var d = eth.getBlock(blockNumber).timestamp; 
            gasLimit = gasLimit.div(1000); 
            console.log(blockNumber + "\t" + new Date(d*1000).toUTCString() + "\t" + gasLimit); 
            gasLimit = new BigNumber(0); 
         } 
    } 
} 

> checkAverageGasLimitEvery1000Blocks(300000);
2157994	Sun, 28 Aug 2016 23:43:06 UTC	4713346.869
2158994	Mon, 29 Aug 2016 03:42:56 UTC	4708939.88
2159994	Mon, 29 Aug 2016 07:45:02 UTC	4708287.85
2160994	Mon, 29 Aug 2016 11:47:34 UTC	4708316.478
2161994	Mon, 29 Aug 2016 15:45:58 UTC	4708676.895
2162994	Mon, 29 Aug 2016 19:44:51 UTC	4708325.929
2163994	Mon, 29 Aug 2016 23:41:52 UTC	4708421.299
2164994	Tue, 30 Aug 2016 03:39:10 UTC	4708152.03
2165994	Tue, 30 Aug 2016 07:37:07 UTC	4708272.041
undefined
> checkAverageGasLimitEvery1000Blocks(200000);
2258001	Wed, 14 Sep 2016 13:03:23 UTC	4712840.524
2259001	Wed, 14 Sep 2016 17:05:52 UTC	4707779.419
2260001	Wed, 14 Sep 2016 21:08:15 UTC	4708353.49
2261001	Thu, 15 Sep 2016 00:59:21 UTC	4708248.539
2262001	Thu, 15 Sep 2016 04:56:43 UTC	4708533.085
2263001	Thu, 15 Sep 2016 09:00:54 UTC	4708003.432
2264001	Thu, 15 Sep 2016 12:52:07 UTC	4708592.725
2265001	Thu, 15 Sep 2016 16:52:07 UTC	4708319.255
2266001	Thu, 15 Sep 2016 20:47:42 UTC	4707937.816 // Before attacks
undefined
> checkAverageGasLimitEvery1000Blocks(100000);
2358012	Sat, 01 Oct 2016 02:37:44 UTC	1501264.782 // During attacks
2359012	Sat, 01 Oct 2016 06:55:32 UTC	1499817.045
2360012	Sat, 01 Oct 2016 11:03:35 UTC	1499651.46
2361012	Sat, 01 Oct 2016 15:00:01 UTC	1499774.121
2362012	Sat, 01 Oct 2016 19:22:49 UTC	1499995.815
2363012	Sat, 01 Oct 2016 23:23:05 UTC	1499963.672
2364012	Sun, 02 Oct 2016 03:17:53 UTC	1499896.736
2365012	Sun, 02 Oct 2016 07:12:16 UTC	1498932.193
2366012	Sun, 02 Oct 2016 11:09:21 UTC	1498849.484
undefined
> checkAverageGasLimitEvery1000Blocks(0);
2458027	Mon, 17 Oct 2016 17:23:05 UTC	500720.531
2459027	Mon, 17 Oct 2016 21:27:48 UTC	500262.692
2460027	Tue, 18 Oct 2016 01:33:09 UTC	500222.285
2461027	Tue, 18 Oct 2016 05:34:28 UTC	500228.19
2462027	Tue, 18 Oct 2016 09:30:42 UTC	500262.456
2463027	Tue, 18 Oct 2016 13:27:42 UTC	500266.979 // Just after hard fork
2464027	Tue, 18 Oct 2016 17:18:08 UTC	617823.939
2465027	Tue, 18 Oct 2016 21:14:26 UTC	1000341.647
2466027	Wed, 19 Oct 2016 01:04:48 UTC	1493273.24
undefined
> console.log(new Date().toUTCString() + "\tblockNumber=" + eth.getBlock("latest").number + "\tgasLimit=" + eth.getBlock("latest").gasLimit)
Wed, 19 Oct 2016 05:03:08 UTC	blockNumber=2467038	gasLimit=2541509

The Gas Price

The gasPrice increased during the attacks as a portion of miners stopped accepting transactions and the remaining miners that accepted transactions had their blocks full from the spam transactions. Non-spam transactions were getting dropped and unprocessed by the Ethereum network. For non-spam transactions to be mined, the gasPrice for these transactions had to be increased. From https://etherscan.io/charts/gasprice:
screen-shot-2016-10-19-at-10-25-52

Checking the current gasPrice with the following code, the gasPrice has fallen back to the pre-attack levels:

> console.log(new Date().toUTCString() + "\t" + web3.fromWei(eth.gasPrice, "wei") + " wei =" + web3.fromWei(eth.gasPrice, "ether").toFixed(9) + " ETH");
Wed, 19 Oct 2016 04:40:42 UTC	20000000000 wei =0.000000020 ETH

Regular account to account transactions cost 21,000 gas, which now equates to around 0.000459187432998 ETH or ~ USD 0.005365596876048108, or around half a cent, at 1 ETH = 12.543 USD. At the peak, someone paid a gasPrice of 0.00000091, ~ 45x the normal amount, to push their transactions through the network.

The Uncles

The rate of uncles per 1,000 blocks has been higher than average during the attack period but this is now falling:

function checkUnclesEvery1000Blocks(lookback) {
    var uncles = 0;
    var i;
    var currentBlockNumber = eth.blockNumber - lookback;
    for (i = -10000; i < 0; i++) {
        var blockNumber = currentBlockNumber + i; 
        uncles += eth.getBlockUncleCount(blockNumber); 
        if ((i % 1000) == 0 && i != -10000) { 
            var d = eth.getBlock(blockNumber).timestamp; 
            console.log(blockNumber + "\t" + new Date(d*1000).toUTCString() + "\t" + uncles); 
            uncles = 0; 
        } 
    } 
} 

> checkUnclesEvery1000Blocks(300000);
2157956	Sun, 28 Aug 2016 23:34:05 UTC	82
2158956	Mon, 29 Aug 2016 03:32:53 UTC	80
2159956	Mon, 29 Aug 2016 07:36:15 UTC	87
2160956	Mon, 29 Aug 2016 11:39:24 UTC	74
2161956	Mon, 29 Aug 2016 15:38:41 UTC	79
2162956	Mon, 29 Aug 2016 19:36:45 UTC	70
2163956	Mon, 29 Aug 2016 23:33:04 UTC	71
2164956	Tue, 30 Aug 2016 03:31:21 UTC	83
2165956	Tue, 30 Aug 2016 07:27:07 UTC	78
undefined
> checkUnclesEvery1000Blocks(200000);
2257957	Wed, 14 Sep 2016 12:53:35 UTC	104
2258957	Wed, 14 Sep 2016 16:56:11 UTC	85
2259957	Wed, 14 Sep 2016 20:56:28 UTC	74
2260957	Thu, 15 Sep 2016 00:48:40 UTC	87
2261957	Thu, 15 Sep 2016 04:45:09 UTC	89
2262957	Thu, 15 Sep 2016 08:52:12 UTC	82
2263957	Thu, 15 Sep 2016 12:43:48 UTC	73
2264957	Thu, 15 Sep 2016 16:42:10 UTC	90
2265957	Thu, 15 Sep 2016 20:40:12 UTC	99 // Before attacks
undefined
> checkUnclesEvery1000Blocks(100000);
2357957	Sat, 01 Oct 2016 02:22:16 UTC	118 // During attacks
2358957	Sat, 01 Oct 2016 06:40:46 UTC	299
2359957	Sat, 01 Oct 2016 10:50:06 UTC	186
2360957	Sat, 01 Oct 2016 14:46:25 UTC	267
2361957	Sat, 01 Oct 2016 19:08:04 UTC	302
2362957	Sat, 01 Oct 2016 23:10:05 UTC	304
2363957	Sun, 02 Oct 2016 03:05:49 UTC	285
2364957	Sun, 02 Oct 2016 07:01:00 UTC	243
2365957	Sun, 02 Oct 2016 10:52:56 UTC	235
undefined
> checkUnclesEvery1000Blocks(0);
2457960	Mon, 17 Oct 2016 17:08:27 UTC	85
2458960	Mon, 17 Oct 2016 21:11:54 UTC	106
2459960	Tue, 18 Oct 2016 01:11:26 UTC	127
2460960	Tue, 18 Oct 2016 05:19:24 UTC	132
2461960	Tue, 18 Oct 2016 09:11:13 UTC	178
2462960	Tue, 18 Oct 2016 13:11:06 UTC	142
2463960	Tue, 18 Oct 2016 17:00:59 UTC	96 // After hard fork
2464960	Tue, 18 Oct 2016 20:53:43 UTC	92
2465960	Wed, 19 Oct 2016 00:49:29 UTC	89
undefined

The higher than average rate of uncles during the attack period was most likely due to mining nodes being slowed down by the heavy computational and disk input/output burden caused by the spam transactions.

The Empty Blocks

During the attack, some miners decided not to include any transactions in their mined blocks as processing these transactions would slow down the initial preparation of the block before mining on the block commences – see Dwarfpool Empty Block Mining? and Wall of fame / wall of shame – miners who are doing nothing for the network right now. Here are some statistics that show that empty blocks have not yet reduced to the pre-attack period:

function checkEmptyBlocks(lookback) {
    var emptyBlocks = 0;
    var i;
    var currentBlockNumber = eth.blockNumber - lookback;
    for (i = -10000; i < 0; i++) {
        var blockNumber = currentBlockNumber + i; 
        if (eth.getBlockTransactionCount(blockNumber) == 0) {
            emptyBlocks++;
        }
        if ((i % 1000) == 0 && i != -10000) { 
            var d = eth.getBlock(blockNumber).timestamp; 
            console.log(blockNumber + "\t" + new Date(d*1000).toUTCString() + "\t" + emptyBlocks); 
            emptyBlocks = 0; 
        } 
    } 
}

> checkEmptyBlocks(300000);
2157940	Sun, 28 Aug 2016 23:31:07 UTC	349
2158940	Mon, 29 Aug 2016 03:28:49 UTC	371
2159940	Mon, 29 Aug 2016 07:31:53 UTC	342
2160940	Mon, 29 Aug 2016 11:36:51 UTC	310
2161940	Mon, 29 Aug 2016 15:35:04 UTC	322
2162940	Mon, 29 Aug 2016 19:31:39 UTC	296
2163940	Mon, 29 Aug 2016 23:27:06 UTC	328
2164940	Tue, 30 Aug 2016 03:27:35 UTC	366
2165940	Tue, 30 Aug 2016 07:23:52 UTC	339
undefined
> checkEmptyBlocks(200000);
2257943	Wed, 14 Sep 2016 12:50:38 UTC	169
2258943	Wed, 14 Sep 2016 16:53:22 UTC	173
2259943	Wed, 14 Sep 2016 20:51:47 UTC	228
2260943	Thu, 15 Sep 2016 00:46:35 UTC	317
2261943	Thu, 15 Sep 2016 04:42:50 UTC	352
2262943	Thu, 15 Sep 2016 08:49:47 UTC	178
2263943	Thu, 15 Sep 2016 12:40:43 UTC	240
2264943	Thu, 15 Sep 2016 16:38:55 UTC	180
2265943	Thu, 15 Sep 2016 20:36:42 UTC	203 // Before attacks
undefined
> checkEmptyBlocks(100000);
2357946	Sat, 01 Oct 2016 02:20:30 UTC	451 // During attacks
2358946	Sat, 01 Oct 2016 06:37:36 UTC	440
2359946	Sat, 01 Oct 2016 10:46:48 UTC	438
2360946	Sat, 01 Oct 2016 14:43:29 UTC	449
2361946	Sat, 01 Oct 2016 19:06:09 UTC	426
2362946	Sat, 01 Oct 2016 23:08:16 UTC	379
2363946	Sun, 02 Oct 2016 03:04:02 UTC	409
2364946	Sun, 02 Oct 2016 06:58:24 UTC	512
2365946	Sun, 02 Oct 2016 10:50:42 UTC	523
undefined
> checkEmptyBlocks(0);
2457950	Mon, 17 Oct 2016 17:06:56 UTC	367
2458950	Mon, 17 Oct 2016 21:08:17 UTC	346
2459950	Tue, 18 Oct 2016 01:10:13 UTC	345
2460950	Tue, 18 Oct 2016 05:16:15 UTC	296
2461950	Tue, 18 Oct 2016 09:09:23 UTC	268
2462950	Tue, 18 Oct 2016 13:09:30 UTC	348
2463950	Tue, 18 Oct 2016 16:57:53 UTC	352 // After hard fork
2464950	Tue, 18 Oct 2016 20:52:32 UTC	332
2465950	Wed, 19 Oct 2016 00:47:23 UTC	343
undefined

A Successful Hard Fork

Congratulations to the developers and the Ethereum Foundation for a successful hard fork! The spam transactions have stopped. For a while at least. Update 14:26 Oct 19 2016 UTC – Less than a day of calm.

The Second Hard Fork – State Clearing

There will be the EIP #158 State Clearing hard fork shortly to remove many of the empty accounts filling up the blockchain.

Ethereum Classic Classic?

This gas repricing hard fork was not as contentious as the hard fork to refund the USD 50 million hack on The DAO’s smart contract code with a bug. The Ethereum Classic (ETC) chain arose from this The DAO hard fork as about 10% of miners (who insist on immutable blockchains) continued mining on the non-hard forked chain. And the It-Who-Must-Not-Be-Named exchange listed ETC on their exchange by surprise.

The ETC chain has recently been undergoing similar spam transaction attack and there is a proposal to perform the same hard fork at block 2,500,000 on Oct 25 2016. As this hard fork violates the principle of an immutable blockchain that is a concern for some part of that community, there are calls for a vote before hard forking. There is a small chance that an Ethereum Classic Classic (ETCC) chain may arise from this community split.

A New Set Of Attacks (Update 14:26 Oct 19 2016 UTC)

A new set of attacks using underpriced EXP and BALANCE opcodes is currently occurring – see Lol, I think its another attack contract – Burns fees like a champ. Somone is very persistent here 🙂. The effects on the network are apparently not severe like the previous attacks. And this opcode will be repriced in the next hard fork.

The following logs shows that some blocks are taking longer than usual to process.

// geth running on my Macbook Air - up to 10 seconds to process some blocks
I1020 00:32:51.043543 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 20 txs in 9.659660949s. #2469043 [a8e83598 / a8e83598]
I1020 00:32:56.462486 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 12 txs in 5.413096939s. #2469044 [7539f516 / 7539f516]
I1020 00:32:59.294688 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 1 txs in 7.572923ms. #2469043 [43159825 / 43159825]
I1020 00:33:05.819443 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 0 txs in 10.632415ms. #2469045 [75e40371 / 75e40371]
I1020 00:33:32.557822 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 12 txs in 9.489027618s. #2469046 [46bf1869 / 46bf1869]
I1020 00:33:44.212843 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 4 txs in 12.276909ms. #2469047 [f482688b / f482688b]
I1020 00:34:18.885343 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 12 txs in 10.215295819s. #2469048 [858c89fa / 858c89fa]
I1020 00:34:18.895052 core/blockchain.go:1001] imported 1 block(s) (0 queued 1 ignored) including 13 txs in 9.654351ms. #2469049 [858c89fa / 78704291]
I1020 00:34:29.303799 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 13 txs in 9.512011695s. #2469050 [1b7f7c43 / 1b7f7c43]
I1020 00:34:30.187835 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 0 txs in 6.495512ms. #2469050 [42ba6725 / 42ba6725]
I1020 00:34:42.538841 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 0 txs in 7.477749ms. #2469051 [4af0e2eb / 4af0e2eb]
I1020 00:35:43.635580 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 14 txs in 9.289186837s. #2469052 [d84ff7c8 / d84ff7c8]
I1020 00:35:56.769851 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 18 txs in 23.218423ms. #2469053 [8501f360 / 8501f360]
I1020 00:36:17.192551 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 1 txs in 6.326109ms. #2469054 [99f4c275 / 99f4c275]
I1020 00:36:18.457158 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 0 txs in 5.390568ms. #2469055 [2d9b05bf / 2d9b05bf]

// Parity running on my virtual server - up to 5 seconds to process some blocks
2016-10-20 00:32:43  Imported #2469043 a8e8…5f46 (20 txs, 3.89 Mgas, 4705.67 ms, 3.13 KiB)
2016-10-20 00:32:51  Imported #2469044 7539…b210 (12 txs, 3.68 Mgas, 2941.12 ms, 2.07 KiB)
2016-10-20 00:32:52      0/48/50 peers     19 MiB db    5 MiB chain    2 KiB queue  456 KiB sync
2016-10-20 00:32:56  Imported #2469043 4315…e913 (1 txs, 0.02 Mgas, 1.46 ms, 0.63 KiB)
2016-10-20 00:33:04  Imported #2469045 75e4…862a (0 txs, 0.00 Mgas, 1.67 ms, 1.04 KiB)
2016-10-20 00:33:23      1/48/50 peers     19 MiB db    5 MiB chain    2 KiB queue  457 KiB sync
2016-10-20 00:33:26  Imported #2469046 46bf…fed6 (12 txs, 3.60 Mgas, 2772.87 ms, 2.01 KiB)
2016-10-20 00:33:43  Imported #2469047 f482…905a (4 txs, 1.71 Mgas, 6.98 ms, 6.81 KiB)
2016-10-20 00:33:53      0/48/50 peers     19 MiB db    5 MiB chain    2 KiB queue  456 KiB sync
2016-10-20 00:34:11  Imported #2469048 858c…9920 (12 txs, 3.60 Mgas, 5034.20 ms, 2.01 KiB)
2016-10-20 00:34:21  Imported #2469050 1b7f…708d (13 txs, 3.83 Mgas, 4225.16 ms, 2.60 KiB) + another 1 block(s)
2016-10-20 00:34:24      0/48/50 peers     18 MiB db    5 MiB chain    2 KiB queue  456 KiB sync
2016-10-20 00:34:30  Imported #2469050 42ba…84af (0 txs, 0.00 Mgas, 0.78 ms, 0.52 KiB)
2016-10-20 00:34:41  Reorg to #2469051 4af0…8d1d (1b7f…708d #2469049 7870…6a96 42ba…84af)
2016-10-20 00:34:41  Imported #2469051 4af0…8d1d (0 txs, 0.00 Mgas, 1.91 ms, 0.52 KiB)
2016-10-20 00:34:54      0/48/50 peers     18 MiB db    5 MiB chain    2 KiB queue  456 KiB sync
2016-10-20 00:35:25      0/48/50 peers     18 MiB db    5 MiB chain    2 KiB queue  456 KiB sync
2016-10-20 00:35:31  Imported #2469052 d84f…ca1e (14 txs, 3.85 Mgas, 27.73 ms, 3.22 KiB)
2016-10-20 00:35:55      0/48/50 peers     18 MiB db    5 MiB chain    2 KiB queue  456 KiB sync
2016-10-20 00:35:56  Imported #2469053 8501…bd7d (18 txs, 0.58 Mgas, 15.98 ms, 3.08 KiB)
2016-10-20 00:36:15  Imported #2469054 99f4…4599 (1 txs, 0.50 Mgas, 2.90 ms, 2.58 KiB)
2016-10-20 00:36:17  Imported #2469055 2d9b…d161 (0 txs, 0.00 Mgas, 0.98 ms, 0.51 KiB)
2016-10-20 00:36:25      0/48/50 peers     18 MiB db    5 MiB chain    2 KiB queue  456 KiB sync

// geth running on my solo mining node with a low specced CPU - up to 33 seconds to process some blocks
I1020 00:32:42.742227 miner/worker.go:539] commit new work on block 2469043 with 23 txs & 0 uncles. Took 1.0199364s
I1020 00:33:10.390468 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 20 txs in 28.733235855s. #2469043 [a8e83598 / a8e83598]
I1020 00:33:10.919816 miner/worker.go:539] commit new work on block 2469044 with 23 txs & 0 uncles. Took 524.684959ms
I1020 00:33:22.418526 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 12 txs in 12.024350639s. #2469044 [7539f516 / 7539f516]
I1020 00:33:22.423112 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 1 txs in 4.542614ms. #2469043 [43159825 / 43159825]
I1020 00:33:22.434671 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 0 txs in 7.698511ms. #2469045 [75e40371 / 75e40371]
I1020 00:33:27.477946 miner/worker.go:539] commit new work on block 2469045 with 21 txs & 0 uncles. Took 5.058014449s
I1020 00:33:28.785764 miner/worker.go:539] commit new work on block 2469046 with 23 txs & 0 uncles. Took 1.307781816s
I1020 00:33:55.654967 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 12 txs in 32.302568264s. #2469046 [46bf1869 / 46bf1869]
I1020 00:33:55.668998 core/blockchain.go:1001] imported 1 block(s) (0 queued 1 ignored) including 16 txs in 13.97417ms. #2469047 [46bf1869 / f482688b]
I1020 00:34:00.345290 miner/worker.go:539] commit new work on block 2469047 with 20 txs & 0 uncles. Took 4.684836742s
I1020 00:34:05.221332 miner/worker.go:539] commit new work on block 2469048 with 19 txs & 0 uncles. Took 4.876006493s
I1020 00:34:43.495964 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 12 txs in 33.090771592s. #2469048 [858c89fa / 858c89fa]
I1020 00:34:43.506047 core/blockchain.go:1001] imported 1 block(s) (0 queued 1 ignored) including 13 txs in 10.04303ms. #2469049 [858c89fa / 78704291]
I1020 00:34:43.518285 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 0 txs in 4.48897ms. #2469050 [42ba6725 / 42ba6725]
I1020 00:34:48.324418 miner/worker.go:539] commit new work on block 2469049 with 21 txs & 0 uncles. Took 4.823874484s
I1020 00:34:53.599232 miner/worker.go:539] commit new work on block 2469051 with 20 txs & 0 uncles. Took 5.27477654s
I1020 00:34:55.195663 miner/worker.go:539] commit new work on block 2469051 with 20 txs & 0 uncles. Took 1.596398023s
I1020 00:35:08.630286 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 13 txs in 25.111965254s. #2469050 [1b7f7c43 / 1b7f7c43]
I1020 00:35:08.635657 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 0 txs in 5.339419ms. #2469051 [4af0e2eb / 4af0e2eb]
I1020 00:35:08.709391 miner/worker.go:539] commit new work on block 2469051 with 20 txs & 1 uncles. Took 76.987443ms
I1020 00:35:10.302185 miner/worker.go:539] commit new work on block 2469052 with 20 txs & 1 uncles. Took 1.592757807s
I1020 00:35:36.499455 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 14 txs in 4.071344935s. #2469052 [d84ff7c8 / d84ff7c8]
I1020 00:35:41.447543 miner/worker.go:539] commit new work on block 2469053 with 38 txs & 0 uncles. Took 4.948034828s
I1020 00:35:56.948980 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 18 txs in 27.221715ms. #2469053 [8501f360 / 8501f360]
I1020 00:36:01.533511 miner/worker.go:539] commit new work on block 2469054 with 24 txs & 0 uncles. Took 4.584313659s
I1020 00:36:15.011064 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 1 txs in 5.777414ms. #2469054 [99f4c275 / 99f4c275]
I1020 00:36:17.803840 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 0 txs in 5.008621ms. #2469055 [2d9b05bf / 2d9b05bf]
I1020 00:36:20.096527 miner/worker.go:539] commit new work on block 2469055 with 25 txs & 0 uncles. Took 5.084118022s

Update 09:13 Oct 20 2016 UTC – From FAQ: Upcoming Ethereum Hard Fork – Ethereum Blog, vitalik stated before the new attacks that:

It’s worth noting that an increase in the gas cost of the EXP opcode is likely in HF round 2; this is the one arithmetic opcode that we’ve found that is underpriced (though by a substantially smaller factor than what’s getting fixed in HF round 1).

The Good News (Update 22:03 Oct 19 2016 UTC)

From Lol, I think its another attack contract – Burns fees like a champ. Somone is very persistent here 🙂, gustav_simonsson writes:

Correcting the gas cost of op codes makes Ethereum more efficient as it enables more txs and real throughput by disincentivizing “artificial” use of the platform – simple loops over op codes which has no utility other than DoS.

In fact, the attack surface of Ethereum is surprisingly small given that it’s much more powerful & flexible than other live blockchain systems. This is much due to having cross-client specifications & test suits and multiple implementations in different programming languages.

Claiming the attacker has “unlimited runway to continue” is ignorant FUD.

The vulnerabilities fixed over the past weeks have all been in very specific subsets of the Ethereum protocols:

1. gas cost of a subset of the VM op codes.
2. logic around “empty” accounts
3. performance of state handling of accounts.
4. unconfirmed tx (mempool) queuing & broadcast logic.

(3) and (4) have been vastly improved in geth, parity and other implementations which is why the attacker is no longer targeting these.

(1) was too a large degree fixed by the HF, although it’s clear that EXP (and possibly a few other arithmetic op codes) also need to be adjusted.

(1) and (2) will be further addressed by a 2nd HF (https://github.com/ethereum/EIPs/issues/158)

With the current gas system, there will always be some combination of op codes requiring the most resource usage for the least cost.

Prior to this HF, the block gas limit was voted to 0.5M to ensure the network remained operational and processed txs during attacks.

Now we see that the network is chugging along during attack txs with a at 2M gas limit (although older, slower systems without SSD drives will need patches that are currently being worked on in both geth and parity).

Overall, this HF + patches in clients have improved the bottleneck of Ethereum by more than an order of magnitude. In a few weeks, it’ll be another order of magnitude.

And in the long term all txs we currently describe as “attack” or “DoS” txs will become indistinguishable from regular txs as their tx fees will be proportional to their resource usage.

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