Summarize this article in one sentence.
You can report a DDos attack to law enforcement if you were threatened or blackmailed or if you lost money as a result of the attack. In most cases, contact your national web crime unit.  In the US, file a complaint online with the FBI’s internet crime complaint center here: https://www.ic3.gov/default.aspx. In the UK, call 0300 123 2040 to report the attack to the National Fraud and Cyber Crime Reporting Centre. In Australia, submit an online report to the Cyber Security Center here: https://www.acsc.gov.au/incident.html. In Canada, contact your local police department. To investigate, police will need as much as information about the attack as possible. Tell them what you can about the attack. Be sure to include:  When the attack started and ended. If the attackers asked for a ransom and whether you paid it. If you were threatened before the attack. What protocols (UDP/DNS, TCP, or ICMP) were used in the attack. Any unusual patterns or observations during the attack. If you suspect there was a reason behind the attack, be sure to explain why in your report. If you were threatened beforehand or if the attackers asked for money, always include this information. Other reasons behind attacks might include:  You published something with a different ideology than the attacker. You have a competitor or rival. The attack was a distraction to try to steal data from your website or company. If the attackers asked for ransom, threatened you, or sent any message to you, copy the text of these messages. Either upload a copy of the original message or copy and paste the message into your report.  If you already paid a ransom to the attackers, give the investigators the attacker’s crypto currency wallet address or email address. If the agency decides to pursue a case against the attackers, you may be asked for hard copies of your evidence, including emails, payment transactions, or screenshots of the attack. Keep the original copies in a safe place. To encourage law enforcement to investigate the issue, be sure to state any financial impact this attack may have had on your business. If you lost customers, money, or data during the attack, tell them.  State how you earn income from the website. For example, you might sell products, offer online services, or earn money through advertising. Try to come up with estimate of your total losses, based on how much money you typically make in an hour or day from your site. Report any customer or user complaints to help emphasize how the attack affected your network. In a few weeks, you should receive an email regarding your complaint. DDoS attacks can be difficult to prosecute. Unless the government has a strong lead on your attacker, they may not be able to follow up on your complaint.  If law enforcement decides to investigate and prosecute your attackers, you may be asked to supply copies of evidence, such as emails or screenshots of the attack. If they have not decided to investigate at this time, they will notify you. You may be asked to keep your documents in a safe place, just in case they decide to prosecute in the future.

Summary:
File a report with law enforcement if you lost money in the attack. Provide information about the attack. Explain why you think you were attacked. Include any correspondence you had with the attackers. Discuss how the attack affected your business or website. Wait for a response from the investigators.