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A listing of over 100 blog posts on the Security+exam. Posts are organized into categories such as:

 




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Recent Posts

  • Data Acquisition for Evidence

    Data Acquisition for Evidence

    Forensic experts use a variety of forensic procedures to collect and protect data after an attack. If you’re planning to take the SY0-501 exam, you should have a basic understanding of forensics concepts. This includes the process in data acquisition …
  • Filtering Traffic Using Firewall

    Filtering Traffic Using Firewall

    If you’re planning to take the SY0-501 exam, you should understand firewalls and how to filter traffic using a firewall. A firewall filters incoming and outgoing traffic for a single host or between networks. In other words, a firewall can …
  • Business Continuity Strategies

    Business Continuity Strategies

    If you’re planning to take the SY0-501 exam, you should understand business continuity strategies. This includes disaster recovery and continuity of operation concepts. Combined, these help ensure mission-critical functions continue to operate even if a disaster destroys a primary business location. …
  • Implementing File System Security

    Implementing File System Security

    If you’re planning to take the SY0-501 exam, you should have a good understanding of file system security as a method of protecting data. This includes understanding Linux systems that support GNU Privacy Guard (GnuPG or GPG), which is a …
  • Implementing Secure Network Using Devices

    Implementing Secure Network Using Devices

    If you’re planning to take the SY0-501 exam, you should have a basic understanding of implementing a secure network. This includes using various network devices to support organizational security. For example, can you answer this practice test question? Q. Your email …
  • Sample Performance-Based Question

    Sample Performance-Based Question

    A reader recently queried about a sample performance-based question he saw on CompTIA’s website. He was confused by it and wanted to know how he could answer it. Normally, it’s easy to answer these types of queries. I encourage the …
  • Identifying Application Attacks

    Identifying Application Attacks

    If you’re planning to take the SY0-501 exam, you should have a good understanding of the common attacks related to different types of servers. This includes a wide assortment of attacks such as application attacks and gaining some insight into preventing …
  • Near-Future Businesses That Will Require Digital Security Professionals

    Near-Future Businesses That Will Require Digital Security Professionals

    There is typically no shortage of need for digital security professionals. Our world is increasingly digital, and it seems that people are becoming more aware of the threats they face in this world by the day, meaning security is always …
  • Viewing Logs

    Viewing Logs

    While taking the SY0-501 exam, you may come across some questions that require you to read logs. This confuses some people because logs aren’t written in plain English. However, if you understand the objectives of the exam, you should be able …
  • Detecting Attacks and Protecting Systems

    Detecting Attacks and Protecting Systems

    Organizations need to understand and protect themselves from many different types of threat actors. If you’re planning to take the SY0-501 exam, you should have a good understanding of detecting attacks and protecting systems from these attacks. This includes how organizations and …
  • Using Role-based Access Control

    Using Role-based Access Control

    Role-based access control (role-BAC) uses roles to manage rights and permissions for users. This is useful for users within a specific department who perform the same job functions. If you’re planning to take the SY0-501 exam, you should have a …
  • Preventing Data Loss

    Preventing Data Loss

    If you’re planning to take the SY0-501 version of the Security+ exam, you should have a basic understanding of installing and configuring network components, both hardware- and software-based, to support organizational security. This includes using techniques and technologies to prevent data loss. …
  • Implementing Access Management Controls

    Implementing Access Management Controls

    If you’re planning to take the SY0-501 version of the Security+ exam, you should have a basic understanding of implementing identity and access management controls. For example, can you answer this practice test question? Q. Your organization hosts a web site with a …
  • Providing High Availability

    Providing High Availability

    High availability refers to a system or service that needs to remain operational with almost zero downtime. If you’re planning to take the SY0-501 exam, you should have a basic understanding of utilizing different redundancy and fault-tolerance methods. For example, …
  • Account Management Principles

    Account Management Principles

    If you’re planning to take the SY0-501 exam, you should have a good understanding of common account management practices, along with some basic principles used with account management. Improperly configured accounts don’t follow these principles, increasing risks. For example, can you …

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Filtering Traffic Using Firewall

Posted by on July 7 in Security+ | 0 comments

If you’re planning to take the SY0-501 exam, you should understand firewalls and how to filter traffic using a firewall. A firewall filters incoming and outgoing traffic for a single host or between networks. In other words, a firewall can ensure only specific types of traffic are allowed into a network or host, and only specific types of traffic are allowed out of a network or host.

For example, can you answer this practice test question?

Q. An organization has recently had several attacks against servers within a DMZ. Security administrators discovered that many of these attacks are using TCP, but they did not start with a three-way handshake. Which of the following devices provides the BEST solution?

A. Stateless firewall

B. Stateful firewall

C. Network firewall

D. Application-based firewall

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.

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

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 SY0-501 Practice Test Questions


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Host-Based Firewalls

A host-based firewall monitors traffic going in and out of a single host, such as a server or a workstation. It monitors traffic passing through the NIC and can prevent intrusions into the computer via the NIC. Many operating systems include software-based firewalls used as host- based firewalls. For example, Microsoft has included a host-based firewall on operating systems since Windows XP. Additionally, many third-party host-based firewalls are available.

The figure shows the host-based Windows Firewall on Windows 10. Notice that you can configure inbound rules to allow or restrict inbound traffic and outbound rules to allow or restrict outbound traffic. The connection security rules provide additional capabilities, such as configuring an IPsec connection in Tunnel or Transport mode to encrypt the traffic.

Filtering Traffic Using Firewall

Linux systems support iptables and many additions to iptables, such as ipv6tables, arptables, and so on. Generically, administrators commonly refer to these as xtables. You can configure rules within different tables. Combined, these rules work just like an ACL.

Personal firewalls provide valuable protection for systems against unwanted intrusions. Many organizations use personal firewalls on each system in addition to network firewalls as part of an overall defense-in-depth strategy.

It’s especially important to use personal firewalls when accessing the Internet in a public place. Free Wi-Fi Internet access is often available in public places, such as airports, hotels, and many fast-food establishments, such as Starbucks and McDonald’s. However, connecting to a public Wi-Fi hot spot without the personal firewall enabled is risky, and never recommended.

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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.



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  • A 75 question pre-test
  • A 75 question post-test
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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.

Application-Based Versus Network-Based Firewalls

An application-based firewall is typically software running on a system. For example, host- based firewalls are commonly application-based. A network-based firewall is usually a dedicated system with additional software installed to monitor, filter, and log traffic. For example, Cisco makes a variety of different network-based firewalls. Many of them are dedicated servers with proprietary firewall software installed.

A network-based firewall would have two or more network interface cards (NICs) and all traffic passes through the firewall. The firewall controls traffic going in and out of a network. It does this by filtering traffic based on firewall rules and allows only authorized traffic to pass through it. Most organizations include at least one network-based firewall at the border, between their intranet (or internal network) and the Internet.

Stateless Firewall Rules

Stateless 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. Although 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 identify an IP address to allow or block traffic from a single computer, or from a range of IP addresses, such as from a single subnet. Wildcards such as any or all include all IP addresses.
  • Destination. Traffic is addressed to a destination IP address. You identify an IP address to allow or block traffic to a single computer, or to a range of IP addresses, such as to an entire subnet. 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 systems 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.

Some firewalls require you to include a subnet mask in the rule. For example, if you want to block all SMTP traffic to the 192.168.1.0/24 network, you would use an IP address of 192.168.1.0 and a subnet mask of 255.255.255.0. However, if you only wanted to allow SMTP traffic to a single computer with the IP address of 192.168.1.20/24, you would use an IP address of 192.168.1.20 and a subnet mask of 255.255.255.255.

Stateful Versus Stateless

A stateful firewall inspects traffic and makes decisions based on the context, or state, of the traffic. It keeps track of established sessions and inspects traffic based on its state within a session. It blocks traffic that isn’t part of an established session. As an example, a TCP session starts with a three-way handshake. If a stateful firewall detects TCP traffic without a corresponding three-way handshake, it recognizes this as suspicious traffic and can block it.

A common security issue with stateless firewalls is misconfigured ACLs. For example, if the ACL doesn’t include an implicit deny rule, it can allow almost all traffic into the network.


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SY0-501 Full Security+ Course

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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

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Q. An organization has recently had several attacks against servers within a DMZ. Security administrators discovered that many of these attacks are using TCP, but they did not start with a three-way handshake. Which of the following devices provides the BEST solution?

A. Stateless firewall

B. Stateful firewall

C. Network firewall

D. Application-based firewall

Answer is B. A stateful firewall filters traffic based on the state of the packet within a session. It would filter a packet that isn’t part of a TCP three-way handshake.

A stateless firewall filters traffic based on the IP address, port, or protocol ID.

While it’s appropriate to place a network firewall in a demilitarized zone (DMZ), a network firewall could be either a stateless firewall or a stateful firewall.

An application-based firewall is typically only protecting a host, not a network.

See Chapter 3 of the CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide for more information on basic network devices.

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

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