Firewall Rules and Security+

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If you plan to take the Security+ exam, you should have a good understanding of firewall rules and access control lists (ACLs).  This is the second of three posts in a series showing how they’re used on routers and firewalls to restrict traffic. It ends with a challenge to create firewall rules.

Are you ready for the Security+ performance-based questions?

Can you create rules in an ACL?

Firewall Rules

Firewalls use rules implemented as ACLs to identify allowed and blocked traffic. This is similar to how a router uses rules. Firewalls use an implicit deny strategy to block all traffic that is not explicitly allowed. While rules within ACLs look a little different depending on what hardware you’re using, they generally take the following format:

Permission   Protocol   Source   Destination   Port

  • Permission. You’ll typically see this as PERMIT or ALLOW allowing the traffic. Most systems use DENY to block the traffic.
  • Protocol. Typically, you’ll see TCP or UDP here, especially when blocking specific TCP or UDP ports. If you want to block both TCP and UDP traffic using the same port, you can use IP instead. Using ICMP here blocks ICMP traffic effectively blocking ping and some other diagnostics that use ICMP.
  • Source. Traffic comes from a source IP address. You can identify a specific IP address to allow or block, or a range of IP addresses. Wildcards such as any or all include all IP addresses.
  • Destination. Traffic is addressed to a destination IP address. You can identify a specific IP address to allow or block, or a range of IP addresses, just as you can with the source. Wildcards such as any or all include all IP addresses.
  • Port or protocol. Typically you’ll see the well-known port such as port 80 for HTTP. However, some devices support codes such as www for HTTP traffic. Some system support the use of keywords such as eq for equal, lt for less than, and gt for greater than. For example, instead of just using port 80, it might indicate eq 80.

An important step when deploying a firewall is to determine what traffic you want to allow. You start by assuming you have an implicit deny rule and then you add exceptions for traffic that you want to allow. You then create a rule for each exception. As an example, imagine you have to create rules on a firewall to meet the following requirements:

  1. Allow all HTTP traffic to a web server with an IP of 192.168.1.25.
  2. Allow all HTTP and HTTPS traffic to a web server with an IP of 192.168.1.25.
  3. Allow DNS queries from any source to a computer with an IP of 192.168.1.10.
  4. Block DNS zone transfer traffic from any source to any destination.
  5. Block all DNS traffic from any source to any destination.
  6. Implement implicit deny.

How many rules would you create? What protocols would you use? What ports? The table in the next post shows the solution.

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 Remember this

Firewalls use a deny any any, deny any, or a drop all statement at the end of the ACL to enforce an implicit deny strategy. The statement forces the firewall to block any traffic that wasn’t previously allowed in the ACL. The implicit deny strategy provides a secure starting point for a firewall.

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Page 1 of 3 ACLs and Security+

Page 2 Firewall Rules and Security+  (this page)

Page 3 Firewall Rules Solution

Security+ Practice Test Questions

SYO-501 Practice Test Questions Now Available

SYO-401 Practice Test Questions

Over 440 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.

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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 - 100 random questions. View 100 random questions from the full test bank similar to how the Security+ exam has a potential maximum of 100 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 Security+ (SYO-401) Practice Test Questions Here

 SYO-401 Practice Test Questions


INCLUDES QUESTIONS TO HELP YOU PREPARE

FOR THE NEW PERFORMANCE BASED QUESTIONS 

Bonus - Performance Based Questions

Additional Security+ questions to help you prepare for the new performance based questions. These are included with the full bank of Security+ practice test questions and are divided into different sections. For example, you'll have access to the following links:

- Performance Based Question - Set 1

You'll see a graphic explaining what you might be required to do on the actual exam to match different types of security to mobile devices and servers in a data center. You'll then have two questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 2

You'll see a graphic explaining what you might be required to do on the actual exam to match different types of attacks with the name of the attack type. You'll then have five questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 3

You'll see a graphic showing a network with computers and servers separated by a firewall. The firewall is used to control traffic between the computers and users using rules within an access control list (ACL).  You'll have three questions that test your knowledge and ability to correctly identify the relevant components of the rule. The incorrect answers and explanation provide you with insight into how to correctly answer this type of question on the actual exam.

- Performance Based Question - Set 4

You'll see a graphic explaining what you might be required to do on the actual exam related to what a forensic analyst would do during an investigation. You'll then have two questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 5

You'll see a graphic explaining what you might be required to do on the actual exam to match protocols and ports. You'll then have seven questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 6

You'll see a list of security controls along with a graphic showing devices and locations within an organization, along with instructions on what you might be required to do on the actual exam to match the controls with the devices and locations. You'll then have four questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 7

You'll see a list of authentication methods and authentication factors along with instructions on what you might be required to do on the actual exam to match the authentication methods with the authentication factors. You'll then have six questions that test your knowledge and ability to correctly answer the questions. This set also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 8

You'll see a graphic explaining what you might be required to do on the actual exam to match different types of attacks with the name of the attack type. You'll then have five questions that test your knowledge and ability to correctly answer the questions. This is similar to Set 2 but expands on the possibilities. The set also includes a link to a page showing the end solution for the overall performance based question simulation.

New - Performance Based Question - Set 9

New questions recently added using a different testing engine. See a demo here. This set includes drag and drop and matching questions on ports.

New - Performance Based Question - Set 10

A random set of 20 performance-based questions using drag and drop, matching, sorting, and fill in-the blank. This set includes performance-based questions on RAID.

Get the full bank of Security+ (SYO-401) Practice Test Questions Here

Get the full bank of Security+ Practice Test Questions

Click here if you're looking for SYO-501 Practice Test Questions

Simulated Performance-based Questions

Bonus - Performance Based Questions

Simulated performance-based questions included with all

packages that include practice test questions.

Additional Security+ questions to help you prepare for the new performance based questions. These are included with the full bank of Security+ practice test questions and are divided into different sections. For example, you'll have access to the following links:

- Performance Based Question - Set 1

You'll see a graphic explaining what you might be required to do on the actual exam to match different types of security to mobile devices and servers in a data center. You'll then have two questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 2

You'll see a graphic explaining what you might be required to do on the actual exam to match different types of attacks with the name of the attack type. You'll then have five questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 3

You'll see a graphic showing a network with computers and servers separated by a firewall. The firewall is used to control traffic between the computers and users using rules within an access control list (ACL).  You'll have three questions that test your knowledge and ability to correctly identify the relevant components of the rule. The incorrect answers and explanation provide you with insight into how to correctly answer this type of question on the actual exam.

- Performance Based Question - Set 4

You'll see a graphic explaining what you might be required to do on the actual exam related to what a forensic analyst would do during an investigation. You'll then have two questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 5

You'll see a graphic explaining what you might be required to do on the actual exam to match protocols and ports. You'll then have seven questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 6

You'll see a list of security controls along with a graphic showing devices and locations within an organization, along with instructions on what you might be required to do on the actual exam to match the controls with the devices and locations. You'll then have four questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 7

You'll see a list of authentication methods and authentication factors along with instructions on what you might be required to do on the actual exam to match the authentication methods with the authentication factors. You'll then have six questions that test your knowledge and ability to correctly answer the questions. This set also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 8

You'll see a graphic explaining what you might be required to do on the actual exam to match different types of attacks with the name of the attack type. You'll then have five questions that test your knowledge and ability to correctly answer the questions. This is similar to Set 2 but expands on the possibilities. The set also includes a link to a page showing the end solution for the overall performance based question simulation.

New - Performance Based Question - Set 9

New questions recently added using a different testing engine. See a demo here. This set includes drag and drop and matching questions on ports.

New - Performance Based Question - Set 10

A random set of 20 performance-based questions using drag and drop, matching, sorting, and fill in-the blank. This set includes performance-based questions on RAID.

Get the full bank of Security+ Practice Test Questions Here

Simulated performance-based questions included with

all packages that include practice test questions.

2 Comments

  1. Do I use /32 for every firewall rule that I need to identify a computer or server individually in the rule or is there an equation that I have to use to figure out the mask for the individual computer? For instance is it always /32 or is it sometimes /20 or / 17…? Also in the video here you show that the source and destination both have /32 but in the Performance Based problems on GetCertifiedGetAhead the destination address do not have a /32, why is that?

    • Here’s a cut and paste from the next page in this series. I’ve formatted it differently to stress what you’re asking.

      IP addresses and networks. You can add a rule in the ACL to block access from any single computer based on the IP address.

      If you want to block traffic from one subnet to another, you can use a rule to block traffic using the subnet IDs. For example, the sales department may be in the 192.168.1.0/24 network and the accounting department may be in the 192.168.5.0/24 network. You can ensure traffic from these two departments stays separate with an ACL on a router.

      If you want to block traffic to a single computer you would use /32. For example if you wanted to block traffic to a computer with an IP address of 192.168.1.1, you would use 192.168.1.1/32.

      The performance based questions have different scenarios. Also, they all have full explanations.

      If the scenario requires you to block access to the network, use /24 (or whatever the CIDR notation is that for that network).

      If the scenario requires you to block access to a computer, use /32.

      This is a great example of how a subtle change in the wording of a question is extremely important. CompTIA isn’t trying to trick people with these questions. Instead, they are simply trying to ensure that people understand the difference. People that memorize practice questions and answers have problems. People (like you right now) that try to understand the content, do better.

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