Comparing IPSs and IDSs

Posted by in Security+ | 0 comments

If you’re planning to take the SY0-501 exam, you should have a basic understanding of some of the more advanced network security concepts. This includes intrusion detection systems (IDSs) and intrusion prevention systems (IPSs).

For example, can you answer this practice test question?

Q. Attackers have recently launched several attacks against servers in your organization’s DMZ. You are tasked with identifying a solution that will have the best chance at preventing these attacks in the future. Which of the following is the BEST choice?

A. An out-of-band IPS

B. An in-band IPS

C. A passive IDS

D. An out-of-band IDS

More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation are available at the end of this post.

IPS Versus IDS—Inline Versus Passive

Intrusion prevention systems (IPSs) are an extension of IDSs. Just as you can have both a HIDS and a NIDS, you can also have a HIPS and a NIPS, but a network-based IPS (NIPS) is more common. There are some primary distinctions of an IPS when compared with an IDS:

  • An IPS can detect, react, and prevent attacks.
  • In contrast, an IDS monitors and will respond after detecting an attack, but it doesn’t prevent them.
  • An IPS is inline with the traffic. In other words, all traffic passes through the IPS and the IPS can block malicious traffic. This is sometimes referred to as in-band.
  • In contrast, an IDS is out-of-band. It monitors the network traffic, but the traffic doesn’t go through the IDS. This is sometimes referred to as passive.

Full Security+ Course

SY0-501 Full Security+ Course

Helping you Pass the First Time

Online access includes all of the content from the

CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide

  • Introduction
  • About the exam (including information on the number of questions, test duration, passing score, types of questions and more. Also includes a listing of the exam objectives)
  • 75 question pre-assessment exam
  • Mastering Security Basics (full content from Chapter 1 of the study guide including the exam topic review and 15 practice test questions)
  • Understanding Identity and Access Management (full content from Chapter 2 of the study guide including the exam topic review and 15 practice test questions)
  • Exploring Network Technologies and Tools (full content from Chapter 3 of the study guide including the exam topic review and 15 practice test questions)
  • Securing Your Network (full content from Chapter 4 of the study guide including the exam topic review and 15 practice test questions)
  • Securing Hosts and Data (full content from Chapter 5 of the study guide including the exam topic review and 15 practice test questions)
  • Comparing Threats, Vulnerabilities, and Common Attacks (full content from Chapter 6 of the study guide including the exam topic review and 15 practice test questions)
  • Protecting Against Advanced Attacks (full content from Chapter 7 of the study guide including the exam topic review and 15 practice test questions)
  • Using Risk Management Tools (full content from Chapter 8 of the study guide including the exam topic review and 15 practice test questions)
  • Implementing Controls to Protect Assets (full content from Chapter 9 of the study guide including the exam topic review and 15 practice test questions)
  • Understanding Cryptography and PKI (full content from Chapter 10 of the study guide including the exam topic review and 15 practice test questions)
  • Implementing Policies to Mitigate Risks (full content from Chapter 11 of the study guide including the exam topic review and 15 practice test questions)
  • 75 question post-assessment exam
  • Glossary

Get the SY0-501 Full Security+ Course Here


Test your readiness with these quality materials

Random 75-question tests

Random practice tests from the all of the practice test questions in the CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide. All questions include explanations so you'll know why the correct answers are correct, and why the incorrect answers are incorrect.

3 sets Performance-based Questions

Three new sets of performance-based questions with a total of 30 questions. These new questions use a new testing engine that includes realistic drag and drop, matching, sorting, and fill in the blank questions.

Flashcard Set

  • 494 Online Security+ Glossary Flashcards
  • 222 Online Security+ Acronyms Flashcards
  • 223 Online Security+ Remember This Slide from the popular CompTIA Security+ Get Certified Get Ahead: SY0-501 Study Guide

Audio - SY0-501 Security+ Remember This Audio Files

Learn by Listening. Over one hour and 20 minutes of audio (MP3 downloads.)

Audio - SY0-501 Security+ Question and Answer Audio Files

Learn by Listening. Over two hours hour and 53 minutes of audio (MP3 downloads.)

Bonus #1

Audio from the end of chapter reviews from each of the chapters in the CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide. Over one hour and 40 minutes of additional audio.

Bonus #2

Access to all of the online content that is available for free to anyone that purchases the CompTIA Security+ Get Certified Get Ahead: SY0-501 Study Guide. This includes labs, extra practice test questions, and supplementary materials

Bonus #3 

Access the study materials for a total of 60 days because sometimes life happens.

Get the SY0-501 Full Security+ Course Here

Most IDSs will only respond by raising alerts. For example, an IDS will log the attack and send a notification. The notification can come in many forms, including an email to a group of administrators, a text message, a pop-up window, or a notification on a central monitor. Some IDSs have additional capabilities allowing them to change the environment in addition to sending a notification.

For example, an IDS might be able to modify access control lists (ACLs) on firewalls to block offending traffic, close processes on a system that were caused by the attack, or divert the attack to a safe environment, such as a honeypot or honeynet. While this is sometimes referred to as an active IDS, this phrase can be misleading.

Specifically, the CompTIA Security+ objectives use the terms inline and in-band for an IPS and passive and out-of-band for an IDS.

CompTIA Security+ Study Guide

The 501 Version of the Study Guide

The CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide is an update to the top-selling SY0-201, SY0-301, and SY0-401 study guides, which have helped thousands of readers pass the exam the first time they took it.  It includes the same elements readers raved about in the previous three versions.

Each of the eleven chapters presents topics in an easy to understand manner and includes real-world examples of security principles in action.

You’ll understand the important and relevant security topics for the Security+ exam, without being overloaded with unnecessary details. Additionally, each chapter includes a comprehensive review section to help you focus on what’s important.



Over 300 realistic practice test questions with in-depth explanations will help you test your comprehension and readiness for the exam. The book includes:

  • A 75 question pre-test
  • A 75 question post-test
  • Practice test questions at the end of every chapter.

Each practice test question includes a detailed explanation to help you understand the content and the reasoning behind the question. You’ll be ready to take and pass the exam the first time you take it.

If you plan to pursue any of the advanced security certifications, this guide will also help you lay a solid foundation of security knowledge. Learn this material, and you’ll be a step ahead for other exams. This SY0-501 study guide is for any IT or security professional interested in advancing in their field, and a must-read for anyone striving to master the basics of IT security.

Kindle edition also available.

As a reminder, both IDSs and IPSs have protocol analyzer capabilities. This allows them to monitor data streams looking for malicious behavior. An IPS can inspect packets within these data streams and block malicious packets before they enter the network.

In contrast, a NIDS has sensors or data collectors that monitor and report the traffic. An active NIDS can take steps to block an attack, but only after the attack has started. The inline configuration of the IPS allows an IPS to prevent attacks from reaching the internal network.

As an example, the figure shows the location of two network-based IPSs (NIPS 1 and NIPS 2). All Internet traffic flows through NIPS 1, giving it an opportunity to inspect incoming traffic. NIPS 1 protects the internal network by detecting malicious traffic and preventing attacks from reaching the internal network.

Comparing IPSs and IDSs

NIPS used to detect and prevent attacks

NIPS 2 is protecting an internal private network. As an example, imagine that Homer needs to manage some equipment within a supervisory control and data acquisition (SCADA) network in the nuclear power plant. The SCADA equipment is in the private network. The firewall next to NIPS 2 can have rules that allow traffic from Homer’s computer into the network, but block all other traffic. NIPS 2 will then inspect all the incoming traffic and block malicious traffic.

This might seem like overkill, but many advanced persistent threats (APTs) have successfully installed remote access Trojans (RATs) onto internal systems through phishing or malware attacks. Once the RAT is installed, attackers can now attack from within. If an attacker began launching attacks on the private network from Homer’s system, the firewall wouldn’t block it. However, the NIPS will prevent this attack from reaching the private network.

Notice that each IPS is placed on the edge of the protected network. NIPS 1 is placed on the edge of the network between the Internet and the demilitarized zone (DMZ). NIPS 2 is on the edge of the SCADA network between it and the intranet. This placement ensures that the NIPS can inspect all traffic going into the network.


Security+ Practice Test Questions

SY0-501 Practice Test Questions 

Over 300 realistic Security+ practice test questions

All questions include explanations so you'll know why the correct answers are correct,

and why the incorrect answers are incorrect.

Pass the Security+ Exam

the First Time You Take It

Multiple quiz formats to let you use these questions based on the way you learn.
  • Learn mode - randomized. View each of the questions in random order. Learn mode allows you to keep selecting answers until you select the correct answer. Once you select the correct answer, you'll see the explanation. Click here to see how learn mode works.
  • Learn mode - not randomized. View each of the questions in the same order. Use this if you want to make sure that you see all of the questions. Learn mode allows you to keep selecting answers until you select the correct answer. Once you select the correct answer, you'll see the explanation. Click here to see how learn mode works.
  • Test mode - randomized. View each of the questions in random order. In test mode, you can only see the correct answers and explanations after you complete the test. Click here to see how test mode works.
  • Test mode - not randomized. View each of the questions in the same order. In test mode, you can only see the correct answers and explanations after you complete the test. Click here to see how test mode works.
  • Test mode - 75 random questions. View 75 random questions from the full test bank similar to how the Security+ exam has a potential maximum of 75 multiple choice questions. In test mode, you can only see the correct answers and explanations after you complete the test. Click here to see how test mode works.

Get the full bank of SY0-501 Practice Test Questions Here

 SY0-501 Practice Test Questions


INCLUDES QUESTIONS TO HELP YOU PREPARE

FOR THE NEW PERFORMANCE BASED QUESTIONS 

Bonus - Performance Based Questions

Three sets of performance-based questions including over 30 questions. These questions show you what you can expect in the live exam. They include drag and drop, matching, sorting, and fill in the blank questions. See a demo here.

Bonus - Extra Practice Test Questions

New multiple-choice questions in the extra test bank. Questions are added occasionally. You can see what has been added recently here.

Get the full bank of Security+ (SYO-501) Practice Test Questions Here

Get the full bank of Security+ Practice Test Questions

Click here if you're looking for SY0-501 Full Study Package

Q. Attackers have recently launched several attacks against servers in your organization’s DMZ. You are tasked with identifying a solution that will have the best chance at preventing these attacks in the future. Which of the following is the BEST choice?

A. An out-of-band IPS

B. An in-band IPS

C. A passive IDS

D. An out-of-band IDS

Answer is B. The best solution of the given choices is an in-band intrusion prevention system (IPS). Traffic goes through the IPS and the IPS has the best chance of preventing attacks from reaching internal systems.

An IPS is in-band not out-of-band.

An intrusion detection system (IDS) is passive and not in-band, so it can only detect and react to the attacks, not block them.

See Chapter 4 of the CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide for more information on IDSs and IPSs.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

CompTIA Security+ Get Certified Get Ahead: SY0-501 Study Guide

Subscribe To Our Newsletter

Join our mailing list and get a free excerpt of the CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide.  This excerpt includes the introduction and Chapter 1. 

You have Successfully Subscribed!

Get Certified Get Ahead is a participant in the Amazon Services LLC Associates Program,
an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.

Copyright © 2015 Get Certified Get Ahead. All Rights Reserved.