NIST Special Publication 800-53 provides a catalog of security and privacy controls for all U.S. federal information systems except those related to national security. It is published by the National Institute of Standards and Technology, which is a non-regulatory agency of the United States Department of Commerce.
NIST develops and issues standards, guidelines, and other publications to assist federal agencies in implementing the Federal Information Security Modernization Act of 2014 (FISMA) and to help with managing cost-effective programs to protect their information and information systems.

Incident Handling and Response Incident handling and response (IH&R) is the process of taking organized and careful steps when reacting to a security incident or cyberattack. Steps involved in the IH&R process: 3.
Incident Triage - The IH&R team further analyzes the compromised device to find incident details such as the type of attack, its severity, target, impact, and method of propagation, and any vulnerabilities it exploited. (P.
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Comprehensive and Detailed Explanation:
The OpenSSL command-line utility s_client is used to test SSL/TLS connections.
Correct syntax:
openssl s_client -connect www.website.com:443
This command will initiate a TLS connection to port 443 on the given domain and allow you to inspect certificates, cipher suites, and server responses.
From CEH v13 Courseware:
Module 12: Cryptography # SSL/TLS Testing Tools
Reference:OpenSSL Project Documentation - s_client Usage