Home
>
Software
>
Cisco Certification: Introduction To ISDN, Part III

Cisco Certification: Introduction To ISDN, Part III

Configuring PPP PAP Authentication

Now we know how the ISDN link comes up (interesting traffic), and some scenarios that might cause the link to stay up, we need to look at ISDN authentication schemes. The two methods Cisco certification candidates must be familiar with are PAP and CHAP.

Password Authentication Protocol (PAP) sends the username and password over the ISDN link in clear-text. Sending any passwords over any WAN link in clear-text is generally a bad idea, but it???s important to know you have this option.

Regarding both PAP and CHAP, it???s a common misunderstanding that each side must authenticate the other. PAP and CHAP both support bidirectional and unidirectional authentication that is, R1 can authenticate R2 without R2 necessarily authenticating R1. It???s more common to use unidirectional authentication in a lab environment than a production network, but keep in mind that bidirectional authentication is an option, not a requirement.

The configurations of PAP and CHAP do have their similarities. For both, you???ll configure a username/password combination in global configuration mode. Newcomers to ISDN sometimes put the local router name in for the username remember that the remote router name is the username.

The only real advantage of PAP over CHAP comes in the password configuration. Since PAP actually sends the password as a whole over the link, the two routers can send different passwords during authentication. The operation of CHAP requires that both routers use the same password, and we???ll see why in tomorrow???s article.

Under the BRI interface, you???ll enter encapsulation ppp and ppp authentication pap. So far, your authentication scheme looks like this:

username R2 password CCNA

Int bri0

encapsulation ppp

ppp authentication pap

PAP requires an extra command at this point. The ppp pap sent-username command is required under the interface, indicating the username and password this router will be sending to the remote router.

Int bri0

encapsulation ppp

ppp authentication pap

ppp pap sent-username R1 password CISCO

I always encourage CCNA and CCNP candidates to use as many debugs as possible when working in their lab, since these commands show us how things work. For any PPP authentication, always run debug ppp negotiation before sending interesting traffic to trigger the call. Watching exactly how PAP and CHAP work give you a much better understanding of what???s going on ???behind the command???, and makes you a stronger candidate and a stronger networking engineer.

Tomorrow, we???ll take a look at CHAP, and why routers cannot use the same password on both ends of the link.

Keep studying!

About The Author:

Chris Bryant, CCIE (TM) #12933, has been active in the Cisco certification community for years. He worked his way up from the CCNA to the CCIE, and knows what CCNA and CCNP candidates need to know to be effective on the job and in the exam room.

He is the owner of http://www.thebryantadvantage.com, where he teaches CCNA and CCNP courses to small groups of exam candidates, ensuring they each receive the individual attention they deserve. Classes are offered over the Internet and in person in select cities. Chris has custom-written the Study Guide and Lab Workbook used in each course - no third-party training materials or simulators are used. You're invited to visit our site and check out our CCNA and CCNP Courses, Flash Card Books, and to sign up for our weekly newsletter written personally by Chris. Chris is always glad to hear from Cisco certification candidates at http://www.thebryantadvantage.com.

recurring cleaning service Wilmette ..

In The News:

New Android malware NGate steals NFC payment codes in real-time, allowing criminals to withdraw cash from ATMs without your card. Learn protection tips.

DoorDash confirms data breach exposing customer names, emails, addresses after social engineering attack. Learn how to protect yourself from scams.

Concerned about Google's AI scanning your Gmail? Learn how to disable Gemini features that access your emails, Drive files and Chat messages for privacy.

Google warns Android users about dangerous fake VPN apps hiding malware that steals passwords, banking details and personal data from phones and tablets.

Apple's digital passport feature lets iPhone users breeze through TSA checkpoints this holiday season using Digital ID technology at 250+ airports.

A new phishing scam targets family photos with fake "Cloud Storage Full" alerts. Criminals steal credit card information through fake sites. Learn protection tips.

South Korean scientists create ultra-thin fabric muscles that turn clothes into robotic assistants, lifting 33 pounds while weighing under half an ounce.

Archer Aviation has acquired Hawthorne Airport for $126M to launch an LA air taxi network ahead of the 2028 Olympics, featuring AI-powered eVTOL operations and next-gen aviation tech.

Stay up to date on the latest AI technology advancements and learn about the challenges and opportunities AI presents now and for the future.

Fake AI apps disguised as "ChatGPT" and "DALL·E" are flooding app stores with dangerous malware that steals data and monitors users without detection.

Fake buyers demand specific vehicle reports from unknown sites to steal credit card information from car sellers, but warning signs can help identify these scams before paying.

Android users can now manage apps across multiple devices more easily with Google Play Store's updated remote uninstall button in the latest update.

NASA's Perseverance rover discovers shiny metallic rock on Mars that could be a meteorite from an ancient asteroid, containing high levels of iron and nickel.

Holiday scams spike during Black Friday and Cyber Monday as criminals exploit your leaked personal data. Learn how to protect yourself from fake stores and phishing.

Commerce Department proposes TP-Link router ban over Chinese security risks. Learn how this potential prohibition could affect your home network and devices.

Hyundai AutoEver America suffered a data breach affecting 2,000 current and former employees, exposing names, Social Security numbers and driver's license information.

Washington court rules automated license plate reader images are public records, even when stored by vendors like Flock Safety, setting precedent for transparency.

Fake airline texts claiming flight cancellations are targeting travelers with convincing scams. Learn how cybercriminals steal personal data and credit card info.

Discover how iOS 26's new Adaptive Power feature automatically extends iPhone battery life by learning your usage patterns and adjusting performance intelligently.

New TikTok malware campaign tricks users into running PowerShell commands that download Aura Stealer, which steals credentials and authentication tokens.

Gaia Family offers fixed upfront pricing for IVF cycles with unlimited embryo transfers and financial protection, partnering with over 100 U.S. fertility clinics.

The Jetsons Act aims to position Pennsylvania as a leader in advanced air mobility by establishing regulations for hybrid ground-air vehicles.

Fake Geek Squad invoice emails are targeting users with convincing charges and urgent phone numbers to steal personal information and money.

Fox News Digital's artificial intelligence newsletter digs into a robot in Russia that faceplanted, George Clooney's alarm and OpenAI's rivalry with the New York Times.

Major data breach at Conduent exposes personal information of 10+ million people. Government contractor hit by cyberattack affecting Medicaid, child support systems.

Cisco Certification: Introduction To ISDN, Part III

Software