parity Ropsten testnet forked at block 296151?

Question

I am seeing what looks like a fork in the Ropsten testnet at block 296151 (Jan 6, 11:14 PM UTC). Is this expected?

My local Parity node (Parity/v1.4.7-beta-f2058bd-20161227/x86_64-macos/rustc1.13.0) shows block hash 0x779e9f9...:

> web3.eth.getBlock(296151)
{ author: '0x18e79a47d8a58bef5aaecbba85ea1420649c64a8',
  difficulty: { [String: '219610162'] s: 1, e: 8, c: [ 219610162 ] },
  extraData: '0xd5830104078650617269747986312e31342e30826d61',
  gasLimit: 4707788,
  gasUsed: 348478,
  hash: '0x779e9f9558143be43f3eeb58ad1aa7764a03cf7f1bda4d1c29c2e1244d5e606f',
  logsBloom: '...',
  miner: '0x18e79a47d8a58bef5aaecbba85ea1420649c64a8',
  mixHash: '0xbbb4c781b116ea5cc9cd7dd0a74f2464111cbfa3ed46bdd55cf31b774491f5ad',
  nonce: '0x0b4ee2bdab75890e',
  number: 296151,
  parentHash: '0x39df9773206e47b6555531ee0829dd91d1c91e4dad705688ddee9e6d6a94cd32',
  receiptsRoot: '0xf25f318553e87dff90cf96ace80ed47f624b44ead13400709cd19fc24f24cdb5',
  sealFields:
   [ '0xbbb4c781b116ea5cc9cd7dd0a74f2464111cbfa3ed46bdd55cf31b774491f5ad',
     '0x0b4ee2bdab75890e' ],
  sha3Uncles: '0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347',
  size: 2185,
  stateRoot: '0x934a68c88a3ca2fea112fb08ef2055c9f1ea8310926de3da98cdb51d69ebad3b',
  timestamp: 1483741759,
  totalDifficulty: { [String: '70295938324374'] s: 1, e: 13, c: [ 70295938324374 ] },
  transactions:
   [ '0x2297defea0253c438c4c7a2d399f60fbdf3c647f9dbd2a558165612251030eb6',
     '0x4542e0daaceda8be6039ec135aad5c45cd2026e17884a6d10fec6a9338dc1d77',
     '0x699761a22a793862eacc5c6f80fee7f0bbef318f8eaf756f40a50edf85755a77',
     '0x7173c6479087a3365ebd412e6ef871b40f5ef1269e42fae265e3cf701aeffcb3',
     '0xc68d9b6d271ac294fbc1f86a703f3cbbfe57020ec4087256893565556de74a30',
     '0xd331437b8862ae97f04468f2fe4af54277299501c5deaeeaeaa5fe9184d4b07d',
     '0x3fb032b0c385eba35130e9d55acafaea6a075d91e7c496181435bad49d312ace',
     '0x7e3e3f41526d453165c2dd4c58e9aa5d6e83398d6ad08a316b6017b4f834c0ac',
     '0xbc3f4a530c26dd9c4cad7803347e33d7add544d56a6abcca538703bc1e4d2663',
     '0x676fb70068c62c9f652ceb5475f96f7ca8efe702b0eb97b0e2dfedd2c53b60f5',
     '0xb12084f5f78ad1e6e388aee22d01cc5015f743da30270c5da99000ca316e6c7b',
     '0x38250f96bf25d98b4f9d54d281f7489f42843a4fafba22acb79db741018e58f1',
     '0x66cc9fdc8645ab142ecb425cbb130f5c153e89c827a87f8f536c46ab60598351',
     '0x5c776d9fadc2f07d4742c5fe6daf41a2997596ec15fee17c60a4da1651daf167' ],
  transactionsRoot: '0x7717f5770efde5508bbe97f306e5897e58741a15777460c888e4b40b6c599d56',
  uncles: [] }

But https://testnet.etherscan.io/block/296151 shows a different block with the same parent:

Height:           296151
TimeStamp:        5 days 14 mins ago (Jan-06-2017 11:14:41 PM +UTC)
Transactions:     0 transactions and 0 contract internal transactions in this block
Hash:             0xb3fe6d6ba7bfa04a9e8c295033e603d617b7dd1c4244f0f70997de0492b7e4c7
Parent Hash:      0x39df9773206e47b6555531ee0829dd91d1c91e4dad705688ddee9e6d6a94cd32
Sha3Uncles:       0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347
Mined By:         0x817562f86cee143236962249453ae54e2b530140 IN 2784 secs
Difficulty:       209,505,820
Total Difficulty: 70,295,928,220,032
Size:             526 bytes
Gas Limit:        4,716,988
Gas Used:         0
Nonce:            0x4880dcc18186c893
Block Reward:     5 Ether
Uncles Reward:    0
Extra Data:       Get forked! (Hex:0x47657420666f726b656421)

Notice the different block hash and "Get forked!" message in extraData.

Infura shows the same block as etherscan.io:

curl -s -X POST -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","method":"eth_getBlockByNumber","params":["296151",false],"id":0}' https://testnet.infura.io/<apikeyXXX>
"result" : {
   "transactionsRoot" : "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
   "totalDifficulty" : "0x3fef0bd4a980",
   "size" : "0x20e",
   "parentHash" : "0x39df9773206e47b6555531ee0829dd91d1c91e4dad705688ddee9e6d6a94cd32",
   "mixHash" : "0x4196dda6dde22c62fbe95160b300935589f2eb5b19826cf01b559b0f7023125d",
   "extraData" : "0x47657420666f726b656421",
   "difficulty" : "0xc7cce1c",
   "hash" : "0xb3fe6d6ba7bfa04a9e8c295033e603d617b7dd1c4244f0f70997de0492b7e4c7",
   "number" : "0x484d7",
   "stateRoot" : "0x263abade588bbce1bc9dcc62f203d3b31c75474145942d88ba4bc2582862c884",
   "miner" : "0x817562f86cee143236962249453ae54e2b530140",
   "transactions" : [],
   "sha3Uncles" : "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
   "gasUsed" : "0x0",
   "gasLimit" : "0x47f9bc",
   "logsBloom" : "...",
   "timestamp" : "0x587024e1",
   "uncles" : [],
   "receiptsRoot" : "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
   "nonce" : "0x4880dcc18186c893"
},

EDIT 1/12/2016:

My local node shows the latest block to be:

> web3.eth.getBlock('latest')
{
author: '0x919eb73b9d4d306188b12874f3efdccb6cdcd1b8',
difficulty: { [String: '11274423'] s: 1, e: 7, c: [ 11274423 ] },
extraData: '0xd783010502846765746887676f312e372e33856c696e7578',
gasLimit: 4712388,
gasUsed: 43104,
hash: '0xc30c5b3874d718de2a4d902f8a971cee4c4b0c0072e6c084c74efd83762efb31',
logsBloom: '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000',
miner: '0x919eb73b9d4d306188b12874f3efdccb6cdcd1b8',
mixHash: '0x9b8167fc2e675f65294c09acd2ef7e48a8467814fb05217260c0df6735ce050b',
nonce: '0x5c8934db7ca0c3da',
number: 304548,
parentHash: '0x890f0b9e8960872a0708c0b4a7310b77088ef6e1b31c8538132427bfeadc8e38',
receiptsRoot: '0x60879c208751b2693f21cdb42430e39534e09dc69885d583579211338d0fba12',
sealFields:
 [ '0x9b8167fc2e675f65294c09acd2ef7e48a8467814fb05217260c0df6735ce050b',
   '0x5c8934db7ca0c3da' ],
sha3Uncles: '0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347',
size: 861,
stateRoot: '0x2bd997576e784437838f33b0d14474468af0f2ae7d48946b281aa843b83f35ae',
timestamp: 1483922649,
totalDifficulty: { [String: '70669121674025'] s: 1, e: 13, c: [ 70669121674025 ] },
transactions:
 [ '0x4fabc7fbd712666527522c985b618fea7be25c5507b066393f258632b65ad5e2',
   '0x22d0cd3abcaad4c221b8f92e74c359bb22ce7d78fb52bb28a356738a8c8db488' ],
transactionsRoot: '0x5f3992b1d9e0cc84bee3b3b876fd87adce1de81b09b74800b107f569f40c4485',
uncles: []
}

It has been stuck on this block for quite a while. The timestamp translates to 2017-01-09T00:44:09.000Z which is about 3 days ago.

EDIT 1/12/2016:

I updated parity to the latest commit from master (Parity/v1.6.0-unstable-887e5f7-20170112/x86_64-macos/rustc1‌​.13.0) and resynced from scratch. Now I get the "main" chain:

> web3.eth.getBlock(296151).hash
'0xb3fe6d6ba7bfa04a9e8c295033e603d617b7dd1c4244f0f70997de0492b7e4c7'

Answer 1

So, the geth monitoring-node first seems to have imported the same one as reported above:

Jan 06 23:29:21 geth-testnet: I0106 22:29:21.064938 core/blockchain.go:1073] imported 1 blocks,    14 txs (  0.348 Mg) in  19.168ms (18.180 Mg/s). #296151 [779e9f95…]

A hash 0x779e9f9558143be43f3eeb58ad1aa7764a03cf7f1bda4d1c29c2e1244d5e606f.

Then, a bit later on:

Jan 07 03:01:22 geth-testnet: I0107 02:01:22.283970 core/blockchain.go:1073] imported 1 blocks,     0 txs (  0.000 Mg) in   3.660ms ( 0.000 Mg/s). #297061 [3f857e90…] 
Jan 07 03:01:33 geth-testnet: I0107 02:01:33.483050 core/blockchain.go:1073] imported 192 blocks,     0 txs (  0.000 Mg) in 395.052ms ( 0.000 Mg/s). #296342 [b3fe6d6b… / 0086e376…] 
Jan 07 03:01:35 geth-testnet: I0107 02:01:35.155511 core/blockchain.go:1073] imported 576 blocks,     0 txs (  0.000 Mg) in 948.451ms ( 0.000 Mg/s). #296918 [cf88cd25… / e11de460…] 
Jan 07 03:01:36 geth-testnet: I0107 02:01:36.089260 core/blockchain.go:1073] imported 134 blocks,     0 txs (  0.000 Mg) in 929.458ms ( 0.000 Mg/s). #297052 [a8cfdb90… / 07022b4a…] 
Jan 07 03:01:39 geth-testnet: I0107 02:01:39.327721 core/blockchain.go:1073] imported 1 blocks,     0 txs (  0.000 Mg) in   3.956ms ( 0.000 Mg/s). #297053 [06757b24…]  

First there's an import of 192 blocks, ending at 296342, so seems to reorg from 296150, which seems consistent. So at Jan 07, 03:01, there seems to have been a 51%-attack performed, rolling out 902 blocks (give or take).

Since Parity has 64-block pruning enabled by default, they would not be able to reorg to the 'canon' chain without a resync from scratch, leaving them on another chain.