Firewalls

12 Key excerpts on "Firewalls"

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  eBook - ePub

  Wireless Mobile Internet Security

  • Man Young Rhee(Author)
  • 2013(Publication Date)
  • Wiley

    (Publisher)

  Chapter 11

  Internet Firewalls for Trusted Systems

  A firewall is a device or group of devices that controls access between networks. A firewall generally consists of filters and gateway(s), varying from firewall to firewall. It is a security gateway that controls access between the public Internet and an intranet (a private internal network) and is a secure computer system placed between a trusted network and an untrusted Internet. A firewall is an agent that screens network traffic in some way, blocking traffic it believes to be inappropriate, dangerous, or both. The security concerns that inevitably arise between the sometimes hostile Internet and secure intranets are often dealt with by inserting one or more Firewalls in the path connecting the Internet and the internal network. In reality, Internet access provides benefits to individual users, government agencies, and most organizations. But this access often creates a threat as a security flaw. The protective device that has been widely accepted is the firewall. When inserted between the private intranet and the public Internet, it establishes a controlled link and erects an outer security wall or perimeter. The aim of this wall is to protect the intranet from Internet-based attacks and to provide a choke point where security can be imposed.

  Firewalls act as an intermediate server in handling SMTP and HTTP connections in either direction. Firewalls also require the use of an access negotiation and encapsulation protocol such as SOCKS to gain access to the Internet, the intranet, or both. Many Firewalls support tri-homing, allowing use of a demilitarized zone (DMZ) network. It is possible for a firewall to accommodate more than three interfaces, each attached to a different network segment.

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  No longer available |Learn more

  Guide to Network Security

  • Michael Whitman, Herbert Mattord, David Mackey, Andrew Green(Authors)
  • 2012(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  In general, a firewall is anything, whether hardware or software (or a combination of hardware and software), that can filter the transmis-sion of packets of digital information as they attempt to pass through a boundary of a network. Figure 4-1 shows a general architecture using Firewalls to help establish network boundaries. 500 Workstations Hubs 2 Switches Switch 15 Internal application and file and print servers Router Firewall Firewall Internet router 4 Web servers and 1 e-mail server DMZ Switch Internet Figure 4-1 General firewall architecture © Cengage Learning 2013 Firewall Overview 135 Copyright 2012 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Network Firewalls bear many resemblances to real-life security checkpoints, like those you encounter in an airport: ● Entry and exit points (called ports) are specified for different types of passengers — in our case, network traffic. (For example, Web page content typically travels through TCP port 80.) ● Information that meets specified security criteria (such as an approved IP address) is allowed to pass, whereas other data is filtered — that is, it can ’ t pass through freely. ● Logging of unauthorized (as well as authorized) accesses both into and out of a network. In addition to these fundamental functions of a firewall, manufacturers have added a slew of features that blur the lines between Firewalls and other security devices (such as intrusion prevention systems, or IPS).

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  eBook - PDF

  Enhancing Computer Security with Smart Technology

  • V. Rao Vemuri(Author)
  • 2005(Publication Date)
  • Auerbach Publications

    (Publisher)

  9 Chapter 2 Network Firewalls Kenneth Ingham and Stephanie Forrest Abstract Firewalls are network devices that help enforce an organization’s security policy. Since their development, various methods have been used to implement Firewalls. These methods filter network traffic at one or more of the seven layers of the ISO network model, most commonly at the application, transport, network, and data-link levels. Newer methods, which have not yet been widely adopted, include protocol normalization and distributed Firewalls. Firewalls involve more than the technology required to implement them. Specifying a set of filtering rules, known as a policy, is typically complicated and error prone. High-level languages have been developed to simplify the task of correctly defining a firewall’s policy. Once a policy has been specified, testing is required to determine if the firewall correctly implements it. Because some data must be able to pass in and out of a firewall for the protected network to be useful, not all attacks can be stopped by Firewalls. Some emerging technologies, such as virtual private networks (VPNs) and peer-to-peer networking, pose new challenges to existing firewall technology. 10 Enhancing Computer Security with Smart Technology 2.1 Introduction The idea of a wall to keep out intruders dates back thousands of years. Over 2000 years ago, the Chinese built the Great Wall for protection from neighboring northern tribes. European kings built castles with high walls and moats to protect themselves and their subjects, both from invading armies and from marauding bands intent on pillaging and looting. The term “firewall” was in use as early as 1764 to describe walls that separated the parts of a building most likely to have a fire (e.g., a kitchen) from the rest of a structure [40]. These physical barriers prevented or slowed a fire’s spread throughout a building, saving both lives and property.

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  eBook - PDF

  Firewalls

  Jumpstart for Network and Systems Administrators

  • John R. Vacca, Scott Ellis(Authors)
  • 2004(Publication Date)
  • Digital Press

    (Publisher)

  Some Firewalls place greater emphasis on blocking traffic, while others emphasize permitting traffic. Probably the most important thing to recognize about a firewall is that it implements an access control policy. If you don’t have a good idea of what kind of access you want to permit or deny, or if you simply permit someone or some product to configure a firewall based on what they or it thinks it should do, then they are making policy for your organization as a whole. In other words, a firewall is a network security product that acts as a barrier between two or more network segments. The firewall is a system (which consists of one or more components) that provides an access control mechanism between your network and the network(s) on the other side(s) of it. A firewall can also provide audit and alarm mechanisms that will allow you to keep a record of all access attempts to and from your network, as well as a real-time notification of things that you determine to be important. Nevertheless, perhaps it is best to describe first what a firewall is not: A firewall is not simply a router, host system, or collection of systems that provides security to a network. Rather, a firewall is an 1.2 Firewall defined 7 Chapter 1 Firewall Internal Network External Network (Internet) Figure 1.1 Firewall example. approach to security; it helps implement a larger security policy that defines the services and access to be permitted, and it is an imple-mentation of that policy in terms of a network configuration, one or more host systems and routers, and other security measures such as advanced authentication in place of static passwords. The main pur-pose of a firewall system is to control access to or from a protected network (a site). It implements a network access policy by forcing connections to pass through the firewall, where they can be examined and evaluated.

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  eBook - PDF

  Intelligent Security Systems

  How Artificial Intelligence, Machine Learning and Data Science Work For and Against Computer Security

  • Leon Reznik(Author)
  • 2021(Publication Date)
  • Wiley-IEEE Press

    (Publisher)

  57 Intelligent Security Systems: How Artificial Intelligence, Machine Learning and Data Science Work For and Against Computer Security , First Edition. Leon Reznik. © 2022 by The Institute of Electrical and Electronics Engineers, Inc. Published 2022 by John Wiley & Sons, Inc. 2 2.1 Firewall Definition, History, and Functions: What Is It? And Where Does It Come From? ! Firewall is a device or program that controls the flow of network traffic between networks or hosts that employ differing security postures (Scarfone and Hoffman 2009). A firewall is a vague concept, but is usually characterized as a barrier or a filter between internal and external network traffic. The name originates from the special device installed in buildings to separate parts that need to be protected from the rooms with open fire places. In order to keep the data safe and secure, many organizations employ Firewalls to separate their networks and hosts from outside segments. When a computer from an internal network makes a connection to the untrusted outside part, packets that might include malicious contents could get transmitted between them. Once a malicious packet gets an access to the resources of the inside computer, then the whole internal network could get compromised. A good firewall will have the ability to detect the harmful packets and also drop them depending upon the situation. Firewalls’ work is controlled by the rules or instructions given to them. Good design of the rules assures improved system operation and results in a safer and more secure system. The way how to design the rules depends a lot on the type of traffic that needs to be analyzed and filtered. Organizations may adopt different Firewalls and thus different rulesets based on the network traffic variant. The best practice of choosing good rulesets is proactive instead of reactive .

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  eBook - PDF

  How to Cheat at Configuring Open Source Security Tools

  • Michael Gregg, Eric Seagren, Angela Orebaugh, Matt Jonkman, Raffael Marty(Authors)
  • 2011(Publication Date)
  • Syngress

    (Publisher)

  This chapter reviews some basic firewall concepts and briefly discusses the different architectural ways to implement a firewall. The meat of this chapter discusses the installation and configuration of free Firewalls to run on both Windows- and Linux-based systems. Finally, once the network edge has been adequately secured, we discuss how to create controlled, secure paths through the perimeter for remote connectivity, including administrative access or remote office/work from home scenarios. Firewall Types No discussion of Firewalls would be complete without a discussion of the different types of Firewalls. This is particularly true in this context, because it allows you to better understand exactly where in the spectrum the free firewall offerings lie. In the networking sense, a firewall is basically any compo- nent (software or hardware) that restricts the flow of network traffic. This is a sufficiently broad defi- nition to allow for all of the various ways people have chosen to implement Firewalls. Some Firewalls are notoriously limited in capability and others are extremely easy to use. Within the realm of Firewalls there are many different ways to restrict network traffic. Most of these methods vary in the level of intelligence that is applied to the decision-making process. For example, to permit or deny traffic based on which network device is the sender or recipient, you would use a packet-filterin S.firewall. In reality, even the simplest packet filtering Firewalls can typically make decisions based on the source Internet Protocol (IP) address, the destination IP address, and the source and/or destination port number. While this type of firewall may sound overly simplistic, con- sider if you have a server running a Web site for use on the Internet.

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  eBook - PDF

  Security Sage's Guide to Hardening the Network Infrastructure

  • Steven Andres, Brian Kenyon, Erik Pack Birkholz(Authors)
  • 2004(Publication Date)
  • Syngress

    (Publisher)

  Selecting the Correct Firewall Solutions in this Chapter: ■ Understanding Firewall Basics ■ Exploring Stateful Packet Firewalls ■ Explaining Proxy-Based Firewalls ■ Examining Various Firewall Vendors Related Chapters: ■ Chapter 4 Attacking Firewalls ■ Chapter 7 Network Switching ■ Chapter 10 Perimeter Network Design ■ Chapter 11 Internal Network Design Chapter 3 77 Summary Solutions Fast Track Frequently Asked Questions Introduction Early in human history, people recognized fire as both a tool and a danger. We could easily say the same thing about information—the right information in the wrong hands has probably destroyed almost as many companies as fires have. Therefore, borrowing an architectural term used to denote a structure for con-taining a potential disaster seems apropos. A firewall , when discussed in the realm of computers, prevents unauthorized access to protected networks from users outside the protected network. Firewalls likely serve as the most important component to network security, second only to the physical security of the network. Prior to the Internet, most Firewalls were used in networks that protected high-security installations where employees had distinct security ratings, such as defense contractors. Firewalls were originally employed for the purpose of allowing certain employees to connect to the inner sanctum of the company’s data as a form of access control. The Internet has changed the purpose and function of the firewall. By plug-ging in a single cable, a network administrator has the potential to make a com-pany’s data as accessible to the CEO as it is to the other six billion people on the planet.The new breed of firewall needs to allow a small population of that six bil-lion to have expanded access, and the rest must be stopped at the door. All this must be accomplished with the flexibility to protect against attacks that hackers haven’t even invented yet.

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  eBook - PDF

  Cybersecurity Operations Handbook

  • John Rittinghouse PhD CISM, William M. Hancock PhD CISSP CISM, John Rittinghouse, PhD, CISM, William M. Hancock, PhD, CISSP, CISM(Authors)
  • 2003(Publication Date)
  • Digital Press

    (Publisher)

  One sad part about Firewalls is that the terminology is much like the word virus: what is a fire- wall and what is not a firewall is subject to interpretation by the vendor and the consumer. At the most basic level, a firewall is a packet-filter facility, which can restrict the flow of packets to and from a network via a set of rules implemented in an interconnection device. Examples of this might be a filtering router capable of restricting which packets can be transmitted and which ones can be received from an Internet connection based upon packet addresses (source and destination), specific IP transport protocol type, and so on. Other types of Firewalls might include intelligent port and socket (application) filters, session-level (user) filters, and a variety of other types of filtering tools that restrict traffic flow. From these definitions, it is plain to see that a firewall is frequently the sum of many different compo- nents that work together to block transmission and reception of traffic. There are three generally accepted types of Firewalls on Internet connec- tions: packet filtering, circuit gateways and application gateways. Static packet filtering Packet filter Firewalls consist of enhanced routers with command-driven fil- ter components. In this manner, the network manager tells the router, via terminal commands or a programming interface, what types of packet con- ditions it is to filter from access to the internal network from the Internet or vice versa. Packet filter Firewalls cannot be implemented on wimpy machines~only true hardware need apply. The performance of the firewall will degrade severely as more filters and conditional filter handling routines are set up. Packet filtering, however, does not handle certain types of trans- actions on a network that are context sensitive (i.e., many packets are required to do something, which, taken as a whole, means a certain condi- tion has occurred that may not be a happy situation).

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  eBook - PDF

  Configuring NetScreen Firewalls

  • Rob Cameron(Author)
  • 2004(Publication Date)
  • Syngress

    (Publisher)

  Making Your Security Come Together In today’s security battlefield it almost seems impossible to win.You must identify the best products and procedures for your organization. If you have all of the suggested security solutions, but not enough staff to manage it, then the solutions may not be effective enough. Simply having the appropriate products is not going to resolve all of your problems; you must effectively understand how to use and configure the products.There is no easy solution regarding the best way to go about securing your organization.This is why companies all over the world spend hundreds of millions of dollars on consulting companies to come in and make security decisions for them. Understanding Firewall Basics A firewall is a device that is part hardware, part software and is used to secure network access.Throughout this book, we will cover every aspect of the NetScreen firewall product line, its usage, and configuration. Before we begin to look at the various aspects of the NetScreen firewall, we need to look at some general firewall information.This will give you a better perspective on the pros and cons of the NetScreen firewall. Firewalls have come a long way since the original inception of the idea. In the first part of this section we discuss the firewall in today’s network. We look at the types of Firewalls and how its importance has increased as well as there increased deployments in each network. Next, the many types of Firewalls are discussed and contrasted and compared. Finally, we will review some common firewall concepts that will be used throughout the book. Types of Firewalls In the past, an organization may have had one firewall that protected the edge of the network. Some companies did not have their network attached to the Internet, or may have had perhaps one or two stations that would dial up to the Internet or to another computer that they needed to exchange data with.

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  eBook - PDF

  Principles of Information Security

  • Michael Whitman, Herbert Mattord(Authors)
  • 2017(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  The best solution is to place the Web servers that contain critical data inside the network and use proxy services from a DMZ (screened network segment), and to restrict Web traffic bound for internal net-work addresses to allow only those requests that originated from internal addresses. This restriction can be accomplished using NAT or other stateful inspection or proxy server Firewalls. All other incoming HTTP traffic should be blocked. If the Web servers only contain advertising, they should be placed in the DMZ and rebuilt on a timed schedule or when — not if , but when — they are compromised. • All data that is not verifiably authentic should be denied. When attempting to convince packet-filtering Firewalls to permit malicious traffic, attackers frequently put an internal address in the source field. To avoid this problem, set rules so that the external firewall blocks all inbound traffic with an organizational source address. Firewall Rules As you learned earlier in this chapter, Firewalls operate by examining a data packet and performing a comparison with some predetermined logical rules. The logic is based on a set of guidelines programmed by a firewall administrator or created dynami-cally based on outgoing requests for information. This logical set is commonly referred to as firewall rules, a rule base, or firewall logic. Most Firewalls use packet header information to determine whether a specific packet should be allowed to pass through or be dropped. Firewall rules operate on the principle of “ that which is not permitted is prohibited, ” also known as expressly permitted rules. In other words, unless a rule explicitly permits an action, it is denied. When your organization (or even your home network) uses certain cloud services, like backup providers or Application as a Service providers, or implements some types of device automation, such as the Internet of Things, you may have to make firewall rule adjustments.

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  eBook - ePub

  Juniper(r) Networks Secure Access SSL VPN Configuration Guide

  • Rob Cameron, Neil R. Wyler(Authors)
  • 2011(Publication Date)
  • Syngress

    (Publisher)

  Chapter 1 Defining a Firewall

  Solutions in this chapter:

  Why Have Different Types of Firewalls?

  Back to Basics: Transmission Control Protocol/Internet Protocol

  Firewall Types

  Summary

  Solutions Fast Track

  Frequently Asked Questions

  Introduction

  When most people think about Internet security, the first thing that comes to mind is a firewall, which is a necessity for connecting online. In it’s simplest form, a firewall is a chokepoint from one network (usually an internal network) to another (usually the Internet). However, Firewalls are also being used to create chokepoints between other networks in an enterprise environment. There are several different types of Firewalls.

  Why Have Different Types of Firewalls?

  Before we delve into what types of Firewalls there are, we must understand the present threats. While there are many types of threats, we only discuss a few of them in this chapter, paying the most attention to those that can be mitigated by Firewalls.

  Ensuring a physically secure network environment is the first step in controlling access to your network’s data and system files; however, it is only part of a good security plan. This is truer today than in the past, because there are more ways into a network than there used to be. A medium- or large-sized network can have multiple Internet Service Providers (ISP’s), virtual private network (VPN) servers, and various remote access avenues for mobile employees including Remote Desktop, browser-based file sharing and e-mail access, mobile phones, and Personal Digital Assistants (Pads).

  Physical Security

  One of the most important and overlooked aspects of a comprehensive network security plan is physical access control. This matter is usually left up to facilities managers and plant security departments, or outsourced to security guard companies. Some network administrators concern themselves with sophisticated software and hardware solutions to prevent intruders from accessing internal computers remotely, while at the same time not protecting the servers, routers, cable, and other physical components from direct access. To many “security-conscious” organization’s computers are locked all day, only to be left open at night for the janitorial staff. It is not uncommon for computer espionage experts to pose as members of cleaning crews to gain physical access to machines that hold sensitive data. This is a favorite ploy for several reasons:

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  eBook - PDF

  Configuring SonicWALL Firewalls

  • Dan Bendell(Author)
  • 2006(Publication Date)
  • Syngress

    (Publisher)

  In this section, we discuss basic security concepts that will prepare you for the final section about Firewalls. In this section, we focus on some of the different aspects of what it takes to have a secure organization. As you will see, there are no hard-and-fast rules about what it really takes to make your net-work secure. I have been to many organizations that would fall well below the line I would say is good security. However, some of those same organizations have gone years without a security breach. On the other hand, I have seen other companies spend much more on their security and have more problems with break-ins and data loss. Much like everything in the world, a balance is the best thing you can have for your network. www.syngress.com 18 Chapter 1 • Networking, Security, and the Firewall The Need for Security Enterprise security is the hottest technology trend today. Every aspect of a com-pany’s data infrastructure has the need for security. With ever–growing, ever-evolving networks in every organization, managing security has become harder. For many organizations, the operating budget for security is less than one percent of there total company budget. When it comes down to purchasing security products, Firewalls are the core product used to secure the enterprise network. However, Firewalls should by no means be the only method used to secure your network, but used effectively, they can mitigate the risks of network security breaches and data loss. With integrated technologies such as anti-virus, deep packet inspection, Uniform Resource Locator (URL) filtering, and virtual private networks (VPNs), the firewall can provide a host of security applications all in one system. As the old saying goes, however, you should never put all of your eggs in one basket.

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