Topic: First time bitcoin user - am I getting scammed? (Read 742 times)

Bitcoin is intentionally designed to make "double spending" (spending the same outputs elsewhere before the first transaction confirms) VERY DIFFICULT to do.

The problem you'd run into is that the entire network has already seen the first transaction, and that transaction is now sitting in the memory pool of unconfirmed transactions on every full peer on the network.  Almost every one of those peers will refuse to acknowledge any "double spend" attempt of the same outputs, and will refuse to relay the "double spend" transaction.  As such, no miner will ever hear of it (and if they do, the vast majority of them will refuse to acknowledge it as well).

At the moment the best you can do is just wait.  This transaction doesn't have any extremely small value inputs or outputs, all of its inputs are already confirmed, and it is less than 1 kilobyte in size.  As such, there's a pretty good chance that the transaction will confirm sometime in the next few days.

If the transaction does not confirm within a few days, the sender could attempt a "double spend" transaction with the same inputs.  This would be a rather technically advanced and complicated process.  There is significant risk of permanently lost bitcoins if any mistakes are made in the attempt.

Here is a service that claims to help people "undo" an unconfirmed transaction:
http://www.bitundo.com/index.html

I don't know if the service is trustworthy (they might just run off with your money and not help you), and I don't know how successful they are.

Double spend essentially means spending the same coins twice, although one of the transactions won't confirm.
Don't do anything yet, I'm not sure if it's possible with Bitcoin Core, or if you need to do something weird like making the raw transaction and signing it.
Just wait for Danny's answer.

Hey man, I have no idea what double spend etc means, if you could tell me how it would've been great, i'll pass it on to the guy who've sent the cash.
Reading some other google answers it seems like it's almost impossible to receive coins if no fee have been paid.

Danny, wouldn't it be better if he double-spent the funds to another address, then resend with fee?

OP, don't act before Danny responds.

You guys are the best. Thanks a lot for all the answers

Bitcoin Core wallet is good.  That wallet will continue to broadcast the transaction until it confirms, so it should confirm eventually.  That wallet will not allow him to respend those bitcoins elsewhere while he is waiting for it to confirm.

To avoid this problem in the future, he should change the default transaction fee in preferences to 0.0001 BTC.

Here's what that setting would look like on an Apple computer, it should be similar in Windows:

Talked with him, he was also new to btc apparently also found out he uses bitcoin core wallet. Is that bad/good?

There is no easy way to add a fee after the transaction has been sent.  Most properly designed wallets will force you to pay a fee when it is necessary.

With a proper fee, a transaction will receive its first confirmation in an average of 10 minutes.  Basically whenever the next block is solved.

Without a proper fee, it is very difficult to predict.  It might confirm with the next block (which might happen in the next few seconds), or it might not confirm for a few days.  It's possible that it won't confirm for weeks, and if he is using a wallet that allows him to respend the unconfirmed bitcoins after a few days, then it is possible that it will never confirm.

There is no way to add a fee after the transaction has been confirmed. Your buyer could send the amount again plus the fee, so it all goes through nicely.

Honestly, without a fee, there are so many variables that no predictions can be made. But don't worry until a few days have passed.

Thanks byt, I have no idea what client he was using. Been waiting 5+ hours now. What happens if it doesnt get confirmed at all?



I'm not really worried about the money since I haven't gave him what he payed for yet. THat's why I thought it was strange. And is there no way to add fee now?


How long can it take before I get one confirm,

It'll probably confirm. Point out to the sender that he did not include the fee, and explain that you are waiting for confirmation. Then wait for a few days before worrying.

wait for 1 confirmation and then send.

No. He is probably just stupid and didn't pay the transaction fee. It might eventually confirm, but it might not.
What client is that guy using?

Okay, so I'll just leave it and see the money as lost? Did he try to scam me?

edit: It's already been about 5hours.

What I just said above is a not that correct. It might never confirm, since he did not add a fee.

Don't send him anything until you reach 1 confirmation. It is supposed to take 10 minutes, but can take up to one hour, but usually doesn't.
So actually around 20-30 minutes.

Okay, so I will receive the money. I haven't send him his stuffs yet so, I'll wait til I can use the money until I'll send. How long will this take do you think?

He just didn't include enough transaction fee. Wait for 1 confirmation, or if you want to be safe, 2.

So I was sent this transaction who seems very weird. Worth noting it's my first time receiving using btc.
I use the wallet multibit and I was sent approx 175 dollars. Theese have been showing up but I can't spend them and it sais unconfirmed.

Here is a screen shot http://sv.tinypic.com/view.php?pic=144blfb&s=8#.U2vI_vl_tVQ.

Also here is the transaction info: https://blockchain.info/tx-index/616b243a3e151963bc875d7cd2a991fc689f717c816769da7fa0c1598bac202b


Should I send him his stuffs or should I wait? Am I gonna get this cash at? It seems really fishy, like he've done something