Email spoofing is the fabrication of an email header in the hopes of duping the recipient into thinking the email originated from someone or somewhere other than the intended source. Because core email protocols do not have a built-in method of authentication, it is common for spam and phishing emails to use said spoofing to trick the recipient into trusting the origin of the message.
The ultimate goal of email spoofing is to get recipients to open, and possibly even respond to, a solicitation.
Although the spoofed messages are usually just a nuisance requiring little action besides removal, the more malicious varieties can cause significant problems and sometimes pose a real security threat.

Tcpdump is a data-network packet analyzer computer program that runs under a command-line interface. It allows the user to display TCP/IP and other packets being transmitted or received over a network to which the computer is attached. Distributed under the BSD license, tcpdump is free software.
https://www.wireshark.org/
Wireshark is a free and open-source packet analyzer. It is used for network troubleshooting, analysis, software and communications protocol development, and education.
NOTE: Wireshark is very similar to tcpdump, but has a graphical front-end, plus some integrated sorting and filtering options.

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Windows Messenger administration
Courier administration is an organization based framework notice Windows administration by Microsoft that was remembered for some prior forms of Microsoft Windows.
This resigned innovation, despite the fact that it has a comparable name, isn't connected in any capacity to the later, Internet-based Microsoft Messenger administration for texting or to Windows Messenger and Windows Live Messenger (earlier named MSN Messenger) customer programming.
The Messenger Service was initially intended for use by framework managers to tell Windows clients about their networks.[1] It has been utilized malevolently to introduce spring up commercials to clients over the Internet (by utilizing mass-informing frameworks which sent an ideal message to a predetermined scope of IP addresses). Despite the fact that Windows XP incorporates a firewall, it isn't empowered naturally. Along these lines, numerous clients got such messages. Because of this maltreatment, the Messenger Service has been debilitated as a matter of course in Windows XP Service Pack 2.

A Ping of Death attack is a type of DoS attack that exploits a vulnerability in the IP protocol that allows packets to be fragmented and reassembled at the destination. The attacker sends a malformed packet that exceeds the maximum size of 65,535 bytes, which causes the target system to crash or become unstable when it tries to reassemble the packet. This attack can affect various operating systems and devices, such as routers, switches, and firewalls. A Ping of Death attack can be detected by monitoring the network traffic for unusually large packets or ICMP messages. References:
* Ping of Death (PoD) Attack
* Denial-of-Service Attacks: History, Techniques & Prevention
* What is a denial-of-service (DoS) attack?

Comprehensive and Detailed Explanation:
An Xmas scan is a type of stealth TCP scan that sets the FIN, PSH, and URG flags. According to RFC 793:
* If the port is closed, the target responds with a TCP RST (Reset) packet.
* If the port is open or filtered, there is no response.
Thus, receiving a RST response indicates a closed port.
From CEH v13 Courseware:
* Module 3: Scanning Networks # TCP Flag Scanning Techniques
Reference:CEH v13 Study Guide - Module 3: Xmas, Null, and FIN ScansRFC 793 - Transmission Control Protocol Specification