Passive Computer and network surveillance Network Wiretapping Fiber tapping Port scan Idle scan Host Keystroke logging Data scraping Backdoor Active Denial-of-service attack DDos or Distributed Denial or service attack is an attempt made by the hacker to block access to a server or a website that is connected to the Internet. This is achieved using multiple computerized systems, which overloads the target system with requests,making it incapable of responding to any query.[20] Spoofing Network Man-in-the-middle Man-in-the-browser ARP poisoning Ping flood Ping of death Smurf attack Host Buffer overflow Heap overflow Stack overflow Format string attack