https://en.wikipedia.org/wiki/Network_Time_Protocol
The Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks.
NTP is intended to synchronize all participating computers within a few milliseconds of Coordinated Universal Time (UTC). It uses the intersection algorithm, a modified version of Marzullo's algorithm, to select accurate time servers and is designed to mitigate variable network latency effects. NTP can usually maintain time to within tens of milliseconds over the public Internet and achieve better than one millisecond accuracy in local area networks. Asymmetric routes and network congestion can cause errors of 100 ms or more.
The protocol is usually described in terms of a client-server model but can easily be used in peer-to-peer relationships where both peers consider the other to be a potential time source. Implementations send and receive timestamps using the User Datagram Protocol (UDP) on port number 123.

-sA (TCP ACK scan)
This scan is different than the others discussed so far in that it never determines open (or even open|filtered) ports. It is used to map out firewall rulesets, determining whether they are stateful or not and which ports are filtered.
The ACK scan probe packet has only the ACK flag set (unless you use --scanflags). When scanning unfiltered systems, open and closed ports will both return a RST packet. Nmap then labels them as unfiltered, meaning that they are reachable by the ACK packet, but whether they are open or closed is undetermined. Ports that don't respond, or send certain ICMP error messages back (type 3, code 0, 1, 2, 3, 9, 10, or 13), are labeled filtered.

A Collision attack is a type of cryptographic attack that targets the hash function. The goal of this attack is to find two different inputs that produce the same hash output. This undermines the integrity of the hashing algorithm, as hash functions are expected to produce a unique output for each unique input.
In practical terms, if two different documents (inputs) produce the same hash value (collision), an attacker can replace a legitimate file with a malicious one without detection, assuming the system validates integrity only via the hash.
CEH v13 defines a collision attack as follows:
"A collision attack focuses on finding two different messages (M1 and M2) that produce the same hash value.
This can compromise digital signatures, certificates, and other security protocols." Reference - CEH v13 Study Guide:
Module 20: Cryptography, Section: "Hashing Algorithms and Attacks", Subsection: "Collision Attacks" Incorrect Options Explained:
* A: Public keys are part of asymmetric encryption, not relevant to collisions.
* B/C: These are incorrect descriptions; collision attacks are not about breaking hashes into parts to retrieve plaintext or private keys.
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Bluesnarfing is the unauthorized access of information from a wireless device through a Bluetooth connection, often between phones, desktops, laptops, and PDAs (personal digital assistant).

18 U.S.C. §1030, also known as the Computer Fraud and Abuse Act (CFAA), is a broad federal statute that criminalizes unauthorized access to computers and related fraudulent activities-including phishing and email scams.
From CEH v13 Official Courseware:
* Module 1: Introduction to Ethical Hacking
* Topic: U.S. Laws Related to Cybercrime
CEH v13 Study Guide states:
"Email-based frauds such as phishing, spoofing, and other social engineering attacks fall under the Computer Fraud and Abuse Act (18 U.S.C. §1030), which criminalizes unauthorized access and fraudulent behavior in computing systems." Incorrect Options:
* B: Relates to credit cards and access devices.
* C: Covers interference with government communication systems.
* D: Covers illegal wiretapping and eavesdropping.
Reference:United States Code - Title 18, Section 1030 (Computer Fraud and Abuse Act)