19
votes
Accepted
Check status of daemon?
I found the easiest way to do this (version 0.12) is to issue the command (not case sensitive):
bitcoin-cli getblockchaininfo
Then, compare the blocks received field, to the headers field. The ...
- 998
17
votes
Creating my own bootstrap.dat?
Bitcoin Core contains a tool to do this properly (filtering out any orphan blocks, putting everything in the correct order — which will work a lot better than just concatenating the block files. It's ...
- 271
14
votes
Accepted
Why is witness data downloaded during IBD in prune mode?
Why do pruned nodes download (segregated) witness data during IBD if much of that data is marked as Assumevalid?
Good question, probably because nobody implemented it. Honestly, I had never ...
- 102k
13
votes
Accepted
Blockchain synchronization is painfully slow / Best way to download blockchain
What usually takes time is the validation of the transactions in the blockchain, not downloading it. Bitcoin Core implements a fully validating node, which does not trust any of the information other ...
- 102k
12
votes
How to know if bitcoind synced?
bitcoind logs the current sync status to its debug.log file:
$ tailf ~/.bitcoin/debug.log
2017-05-26 03:49:16 UpdateTip: new best=0000000000000001e0b7c8cffb8e7fa23909b8728913663decfaebffe24ca689 ...
- 221
12
votes
Accepted
Sync with bitcoin-qt very slow (0,01%)
Bitcoin Core sync very slow
Bitcoin Core is capable of full sync in a relatively short period of time depending mainly on the hardware.
Most of the work done is not actually downloading the blocks, ...
11
votes
Check status of daemon?
You can also just tail the debug.log file in a new terminal window while bitcoind is running. It shows current block height i.e. height=181888 and percentage of download complete i.e. progress=68....
- 210
11
votes
Accepted
Bitcoin Core - Go back to a specific block?
You can't delete the block data themselves, but you can reset the blockchain state to a specific block by using the invalidateblock command. This command will mark a specific block and its descendants ...
- 68.5k
11
votes
Accepted
Does assumevalid lower the security of Bitcoin?
which, as I understand it, makes some data (until 2017?) real without verification.
You understand incorrectly. Firstly, the assumevalid blocks is updated at every major release, so it is at most a ...
- 68.5k
11
votes
Accepted
Is there a way to only sync up to a certain block?
bitcoind supports the argument -stopatheight, which takes the number of blocks to download before halting.
- 15.4k
10
votes
Accepted
What does "Activating Best Chain" mean?
Bitcoin Core maintains two databases:
The block index
The chain state (or UTXO set)
The first one just contains a list of all blocks we know about, valid and invalid. It contains all forks we have ...
- 102k
10
votes
Accepted
Why is it bad to download the full chain from a third party with Bitcoin Core?
No, the chainstate is the nodes view of correctness. It would take many hours or days to re-verify the whole chain on most hardware, so an assumption is made that the state stored at the previous ...
- 15.4k
9
votes
Accepted
Bitcoin core wallet transactions and synchronisation
With Bitcoin Core you'll run a full node. So, for every transaction someone does to your business, your Bitcoin Core wallet need to be synchronized with the complete blockchain.
- 316
9
votes
Accepted
Skip IBD on pruned node?
Such a thing is not implemented in Bitcoin Core, though there is some work towards that (the "assumeutxo" project).
What assumevalid does is just assume that all scripts/signatures in blocks ...
- 102k
8
votes
Can I retrieve my bitcoins from years ago that I never received?
If you still have the wallet.dat file and your password you can access your bitcoins. You do not have to use Bitcoin-Qt 7 and it does not matter if your wallet ever synced before. If the sender sent ...
- 233
8
votes
Accepted
Faking blockchain data in bitcoin-core
Let's say I found a tarball with blockchain data files which I load to my datadir and start my Bitcoin Core client, what sort of attacks am I vulnerable to? Could the files contain fake balances?
It ...
- 102k
8
votes
Accepted
How many peers do you need to securely synchronize with the blockchain?
One! Your full node will check every transaction and every block for validity while synchronizing. You therefore can be sure that whatever blockchain data your node accepts follows all rules of ...
- 72.6k
7
votes
Check status of daemon?
run bitcoind getinfo, compare the block count to the current block height of several major block explorers such as:
https://blockchain.info/
https://www.blocktrail.com/BTC
https://blockexplorer.com/...
- 266
7
votes
My Bitcoin Qt is behind 7 years and 32 weeks
If you shut down your PC and then restart, the Bitcoin sync will pick up where it left off.
The latest transaction your Bitcoin currently knows about is 7 years old, but it won't take 7 years to ...
- 3,431
7
votes
Accepted
Can bitcoin core verify a third party blockchain download?
If you give Bitcoin Core a fully populated data directory, it will use it without any validation.
However, if you only give it the blocks/ subdirectory, it will fully validate it to recreate the ...
- 102k
7
votes
Does running a pruned node support the syncing of other nodes in the network?
does such a node support the syncing of other nodes in the network?
Nodes that are pruned unset the NODE_NETWORK flag, which means that they don't advertise themselves as a potential source for block ...
- 15.4k
7
votes
How are funds verified?
How does a miner verify that the funds are available and not already spent without iterating through the entire Blockchain?
Full nodes do iterate through the entire blockchain, but only once. As they ...
- 18k
6
votes
Accepted
What can I do when the blockchain synchronization is stuck at a specific block?
I had this happen to me once. It was apparently caused by an incompatible peer node.
Delete $HOME/.bitcoin/peers.dat
Restart bitcoind
Afterwards, new compatible peers will be found, and hopefully, ...
- 347
6
votes
Accepted
When I'm downloading the blockchain for the first time, from whom am I downloading it from?
Blocks are downloaded from other nodes in Bitcoin's P2P network using a custom wire protocol. For the initial synch you can imagine it as a torrent with 5000 seeders, though the Bitcoin P2P protocol ...
- 15.4k
6
votes
Accepted
Has the bitcoin network ever been "down"?
A bitcoin node could be down or (extremely rarely as you say) all its peers could be down... but the bitcoin network could not be considered down; you could still synchronize by connecting to ...
- 2,520
6
votes
Accepted
How to check if my node is fully sync'ed
Calling getblockchaininfo is your best bet. It includes a field called verificationprogress, which is an estimate of how much of the chain you have validated.
Alternatively, compare headers to ...
- 8,822
6
votes
Accepted
what is the "Banlist" (Bitcoin Core)
It is a blacklist of erroneous nodes' IP addresses which has accrued a certain amount of banscore due to "misbehaviour". To check what sort of erroneous behaviour is considered "misbehaving", you can ...
- 2,408
6
votes
Accepted
Is -blocknotify triggered during catch-up?
Yes, this is by design.
The notify action is run in the function BlockNotifyCallback (init.cpp), and you can see:
static void BlockNotifyCallback(bool initialSync, const CBlockIndex *pBlockIndex)
{
...
- 23k
6
votes
Accepted
What are the trust assumptions in --assumed-valid in bitcoin core 0.14?
Q1) What are the possible attacks (even though completely theoretical) which are possible in case 2 but not in case 1. Please elaborate security-model change required to shift from Case 1 to Case 2.
...
- 68.5k
6
votes
Accepted
When and how does bitcoin node sync itself?
Always.
When starting up, Bitcoin Core sends out a request to its peers to inform it about the best chains they know about (using a getheaders message).
After that point, it is automatic: peers ...
- 102k
Only top scored, non community-wiki answers of a minimum length are eligible