<p>That's what transaction fees are for. You have to pay a fee for every transaction you want to have included in the block chain, especially if your transaction is for a small amount or if there are many transactions already waiting in the transaction pool.</p>

<p>Also, the size of Bitcoin blocks is limited. There is also a limit on the number of signature operations in a block. The most an attacker can do is to raise transaction fees.</p>

CC BY-SA 3.0
2014-10-01T14:34:27.903Z
2014-10-01T14:34:27.903Z
abacabadabacaba
<p>Miners have the option to include or not include any given transaction in a block. If a particular account (or accounts) is attempting to make a large number of low-value transactions, miners could choose to not include transactions from that address in their blocks. Or, they could rate-limit senders of very small amounts.</p>

CC BY-SA 3.0
2014-10-02T20:12:45.913Z
2014-10-02T20:12:45.913Z
Greg Hewgill
<p>What happens if someone maliciously decides to make squillions of transactions on the Bitcoin network? </p>

<p>I see there being two vulnerabilities. Firstly - computation resources used, though this doesn't seem to be a problem, at this stage, given the size of the mining pool. </p>

<p>But also - blowing out the size of the block chain. What if someone were to persist over a year of spamming transactions?</p>

CC BY-SA 3.0
2014-10-01T15:53:08.667Z
Note that having more transactions doesn't significantly increase the amount of computation required for mining.
Nate Eldredge
<scalability><attack>
Is bitcoin vulnerable to a DOS/spam attack?
user1068446
# Is bitcoin vulnerable to a DOS/spam attack?

(Asked by: username_0 on 2014-10-01)

What happens if someone maliciously decides to make squillions of transactions on the Bitcoin network?

I see there being two vulnerabilities. Firstly - computation resources used, though this doesn't seem to be a problem, at this stage, given the size of the mining pool.

But also - blowing out the size of the block chain. What if someone were to persist over a year of spamming transactions?

**Tags:** scalability, attack

> **Comments:**
> **username_1**: Note that having more transactions doesn't significantly increase the amount of computation required for mining.  

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## 2 answers

### Answer by username_2 on 2014-10-01. Score: 3

That's what transaction fees are for. You have to pay a fee for every transaction you want to have included in the block chain, especially if your transaction is for a small amount or if there are many transactions already waiting in the transaction pool.

Also, the size of Bitcoin blocks is limited. There is also a limit on the number of signature operations in a block. The most an attacker can do is to raise transaction fees.


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### Answer by username_3 on 2014-10-02. Score: 1

Miners have the option to include or not include any given transaction in a block. If a particular account (or accounts) is attempting to make a large number of low-value transactions, miners could choose to not include transactions from that address in their blocks. Or, they could rate-limit senders of very small amounts.


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