Home > Articles > Cisco > CCNA Routing and Switching

This chapter is from the book

Deploying a Secure Wireless Network

Although volumes could be (and have been) written on wireless security, I would just like to discuss the 10,000-foot view of wireless security. This will give you an idea of the areas of focus when you are considering using wireless networking technology in your organization. As soon as you understand these areas, you can begin digging deeper into the technology to find the right fit for your wireless design.

Wireless security can be broken into three major categories: encryption, authentication, and detection.

Wireless Encryption


  • Compare and contrast wireless security features and capabilities of WPA security (including: open, WEP, WPA-1/2)

When you're ready for a technology roller coaster ride, begin studying the history of wireless encryption standards. I mentioned in the preceding chapter that wireless networking technology is so amazing that companies began using it long before the security standards were heavily tested and proven to withstand attacks. So, fasten your seat belt, and let's ride through the evolution of wireless encryption standards, starting where it all began: with WEP.

Wired Equivalent Privacy (WEP)

The WEP standard was the first measure of security released for wireless networking. This encryption method was based on the simple concept of using preshared keys (PSKs) to generate an encryption algorithm. Here's an overview of how the WEP encryption algorithm works: The WEP standard uses an encryption formula called RC4. This is essentially a mathematical formula that takes every piece of data you want to encrypt and scrambles it. The missing piece of this formula is the PSK, which you enter. This is visually demonstrated in Figure 18.1.

Figure 18.1

Figure 18.1 The mechanics of WEP encryption.

When the wireless access point receives data, it uses the reverse formula to decrypt the data. So, for WEP to work successfully, you must manually enter the PSK on both the wireless client and the wireless access point.

When WEP was originally released (in 1997), it used 64-bit encryption, which is considered weak by today's standards. You can compare 64-bit encryption to a math formula with 64 steps. Each step scrambles the original data more and more.

Unfortunately, within a few years of WEP's initial release, major security vulnerabilities were found. The wireless standards groups improved the strength of the WEP algorithm by releasing a 128-bit version in 2002, which some people refer to as WEP2. Although it makes the algorithm slightly more difficult to break, many flaws in the underlying design of WEP caused this security standard to crumble.

Wireless security was suffering in a huge way when WPA was released.

Wi-Fi Protected Access (WPA)

The wireless networking industry faced a major issue. A newer encryption algorithm was needed to combat the weaknesses of WEP, but the more complex encryption algorithms would require more-powerful 802.11-compatible wireless hardware to process the algorithm. By this point, the industry had already purchased millions of wireless access points and wireless cards, so simply saying, "Sorry! Go ahead and scrap all that equipment and buy new stuff." was not an option. In 2003 the Wi-Fi Alliance (a group of extremely smart people sponsored by many organizations) stepped forward and proposed WPA. WPA used a new encryption algorithm called Temporal Key Integrity Protocol (TKIP). TKIP ran on the same wireless hardware that was originally created, and it used a 128-bit encryption algorithm. It was engineered to dramatically increase the number of encryption keys that could be used and virtually eliminated the attacks that were successful on WEP keys. Although WPA was not flawless, it was a tremendous step forward from the original WEP standard.

Wi-Fi Protected Access, Reloaded (WPA2 and 802.11i)

WPA was never meant to solve the world's wireless security problems. Although it was much more secure than WEP, it did have the weakness of using the same old hardware that WEP used. Inherent in that hardware were a few security weaknesses that simply could not be overcome by changing the encryption formula. For that reason, the Wi-Fi Alliance quickly (in 2004) proposed an alternative standard casually called WPA2 and officially called 802.11i.

WPA2 uses a completely different encryption standard known as Advanced Encryption Standard (AES). This encryption standard was standardized by the U.S. government and has been extensively analyzed and tested. The WPA2 standard left behind the old hardware and required that users purchase new wireless hardware (both cards and access points).

To ease the transition, WPA2 hardware can run in backward-compatibility mode to support the original WPA and even WEP standards. This allows an organization to upgrade its wireless access points to the new hardware and still support the older WEP- and WPA-compliant clients. As the clients upgrade to newer wireless devices, WPA2 (and thus AES encryption) can be used.

Wireless Authentication (802.1x)

The wireless encryption we've discussed so far does indeed secure the data, but it has a couple of weaknesses. First, using a preshared key system means that you must go to every wireless device and accurately enter the PSK before the device can communicate on the network. Likewise, keeping the same PSK for an extended amount of time increases the chances of the encryption algorithm's being hacked, so it's a good idea to change the PSK on a regular basis. In a small network of 10 or so wireless devices, this may not be a big deal, but in a large network with hundreds or even thousands of wireless devices, this can be a full-time job. The second issue presented by a PSK system is the inability to remove access. For example, if you are using a PSK among your 50 laptop users on the network, and one of the users leaves the company, you must change the PSK for the 49 other wireless users to eliminate the security vulnerability from the former employee.

Simply relying on a shared PSK among all devices is not a secure or scalable solution for business. What was needed was a method of wireless authentication. This would allow you to have a system of granting or restricting access based on a variety of criteria, such as usernames and passwords or certificates. The industry responded with the ultimate authentication method, which we now know as 802.1x.

Usually when we think of network authentication, we think of accessing an operating system. For example, when you log into a Microsoft Windows domain, you must authenticate using a username and password to gain access to shared resources on the Windows-based servers. When you Telnet to a Cisco device, you must authenticate to gain access to manage the device using the Cisco IOS. 802.1x takes authentication to an entirely new level. Now, you must authenticate to gain access to the Layer 2 LAN network fabric. Now, to access the wireless access point and use the 802.11 network, you must authenticate. You can also apply 802.1x to LAN network switches. When a device plugs into an Ethernet port, it must authenticate before it gains access to that port and, thus, the network.

Think of the possibilities as soon as you begin using network authentication! When a user leaves the company, you can negate her user account on a Microsoft Windows server. This will cause her to lose the ability to log on to the Windows workstation and, at the same time, lose the ability to even plug into a switch port or attach to the wireless network! Talk about cutting off a user! Now, let me give you the basics of how this works.

802.1x designates three network devices that participate in network authentication: the supplicant, the authenticator, and the authentication server. Figure 18.2 shows the placement of these devices.

Figure 18.2

Figure 18.2 Equipment participating in 802.1x authentication.

When the user wants to access the network, he must first send his authentication credentials (such as a username and password) to the authenticator, which forwards them to the authentication server. When the authentication server receives the credentials, it checks them against its database and then tells the authenticator whether the device has passed authentication. If the device fails authentication, its access to the network is terminated or severely limited, depending on how you (as the administrator) decide to restrict the device. If the device passes authentication, the supplicant and authentication server generate a dynamic encryption key known as the session key. This provides the same security as the PSK but does not require you to enter a PSK on the client or wireless access point.

I could say much more about network authentication, but, as I said at the beginning of this section, this is a 10,000-foot overview of the concepts. You now know what network authentication is all about and what it is used for. It's now up to you to continue past the CCNA in your Cisco studies to determine the best method to implement network authentication. Proceed into that world with a grave warning: Don't let the EAP monsters eat you alive! Don't worry; you'll know what I mean when you get there.

Wireless Intrusion Prevention System (IPS)

By using wireless network authentication and encryption, we have addressed the concerns of war driving and network hackers. But what about those pesky users who plug unauthorized wireless access points into the network? For that we have wireless IPS. You can think of IPS as introducing a variety of detection lasers into your network. I think back to the 1996 movie Mission Impossible with Tom Cruise. In one scene, Cruise (well, Ethan Hunt, to be exact) must retrieve a chip from a secured computer room by twisting and contorting his body through a variety of lasers projected around the room. In the same sense, deploying wireless IPS for your network sets up a variety of "sensors" that detect when a policy has been violated. The minute a rogue access point shows up in the network, the system can alert you, pinpointing the location of the access point on a map of your campus. Amazing!

Network-wide IPS can detect a variety of additional suspicious movements around the network, in both the wired and wireless worlds. However, discussing the rest of those detections is part of the Cisco Certified Security Professional (CCSP) certification.

Pearson IT Certification Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Pearson IT Certification and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Pearson IT Certification products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by Adobe Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.pearsonitcertification.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020