Do you know the different remote access authentication mechanisms? You should if you plan to take the Security+ exam. Remote access protocol is an important topic for the exam. Here’s a sample question:
Q. Which of the following provides authentication services and uses PPP?
A. Diameter and biometrics
B. Kerberos and LDAP
C. SAML and SSO
D. PAP and CHAP
Can you answer the question? The answer and explanation is available at the end of this post.
PAP
Password Authentication Protocol (PAP) is used with Point-to-Point Protocol (PPP) to authenticate clients. It replaced Serial Line Interface Protocol (SLIP) as a more efficient method of connecting to remote servers such as Internet Service Providers (ISPs). However, a significant weakness of PAP is that it sends passwords or PINs over a network in cleartext, representing a significant security risk.
PPP was primarily used with dial-up connections. Believe it or not, there was a time when the thought of someone wiretapping a phone was rather remote. Because of this, security was an afterthought with PPP. Today, PPP is only used as a last resort due to passwords being passed in cleartext, or it is used with another protocol that provides encryption.
Sending data across a network in cleartext is a security risk. This is a risk with PPP and with many other protocols such as File Transfer Protocol (FTP). It’s relatively easy for attackers to download and use a free protocol analyzer (such as Wireshark) to capture packets. They can then analyze these packets, and read the data within the packets. Protocol analyzers are commonly referred to as sniffers.
CHAP
Challenge Handshake Authentication Protocol (CHAP) also uses PPP and authenticates remote users, but it is more secure than PAP. The goal of CHAP is to allow the client to pass credentials over a public network (such as a phone or the Internet) without allowing attackers to intercept the data and later use it in an attack.
The client and server both know a shared secret (similar to a password) used in the authentication process. However, the client doesn’t send the shared secret over the network in plaintext as PAP does. Instead, the client hashes it after combining it with a nonce (number used once) provided by the server. This handshake process is used when the client initially tries to connect to the server, and at different times during the connection.
Remember this
PAP authentication uses a password or a PIN. A significant weakness is that PAP sends the information across a network in cleartext, making it susceptible to sniffing attacks. CHAP is more secure than PAP because passwords are not sent over the network in cleartext. Both PAP and CHAP use PPP.
MS-CHAP and MS-CHAPv2
Microsoft introduced Microsoft Challenge Handshake Authentication Protocol (MS-CHAP) as an improvement over CHAP for Microsoft clients. MS-CHAP supported clients as old as Windows 95. Later, Microsoft improved MS-CHAP with MS-CHAPv2.
A significant improvement of MS-CHAPv2 over MS-CHAP is the ability to perform mutual authentication. Not only does the client authenticate to the server, but the server also authenticates to the client. Mutual authentication provides assurances of the server’s identity before the client transmits data, which reduces the risk of a client sending sensitive data to a rogue server.
The 601 Version of the Study Guide
The CompTIA Security+: Get Certified Get Ahead: SY0-601 Study GuideEach 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.
Over 300 realistic practice test questions with in-depth explanations will help you test your comprehension and readiness for the exam. The book includes:
- A 75 question pre-test
- A 75 question post-test
- Practice test questions at the end of every chapter.
Each practice test question includes a detailed explanation to help you understand the content and the reasoning behind the question. You’ll be ready to take and pass the exam the first time you take it.
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 SY0-601 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.
Q. Which of the following provides authentication services and uses PPP?
A. Diameter and biometrics
B. Kerberos and LDAP
C. SAML and SSO
D. PAP and CHAP
Answer is D. Both Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP) use Point-to-Point Protocol (PPP).
Diameter is an authentication service, but biometrics is an authentication method.
Kerberos is an authentication service, but it doesn’t use PPP and Lightweight Directory Access Protocol (LDAP) as a method of querying directories.
Security Assertion Markup Language (SAML) is an Extensible Markup Language (XML)–based data format used for single sign-on (SSO), but it doesn’t use PPP.
