Book Image

Troubleshooting NetScaler

By : Raghu Varma Tirumalaraju
Book Image

Troubleshooting NetScaler

By: Raghu Varma Tirumalaraju

Overview of this book

NetScaler is a high performance Application Delivery Controller (ADC). Making the most of it requires knowledge that straddles the application and networking worlds. As an ADC owner you will also likely be the first person to be solicited when your business applications fail. You will need to be quick in identifying if the problem is with the application, the server, the network, or NetScaler itself. This book provides you with the vital troubleshooting knowledge needed to act fast when issues happen. It gives you a thorough understanding of the NetScaler layout, how it integrates with the network, and what issues to expect when working with the traffic management, authentication, NetScaler Gateway and application firewall features. We will also look at what information to seek out in the logs, how to use tracing, and explore utilities that exist on NetScaler to help you find the root cause of your issues.
Table of Contents (17 chapters)
Troubleshooting NetScaler
Credits
Notice
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

NetScaler Gateway™ VPNs


To get a baseline idea of what a successful login and resource access should look like, over the next few pages we will examine the various stages of a NetScaler Gateway VPN session using a Wireshark capture. The intent is to provide you with the knowledge of a known good trace that you can compare against when troubleshooting issues.

We will then follow up with a discussion of the troubleshooting tools and techniques for troubleshooting NetScaler Gateway VPNs.

Examining VPN session launch using Wireshark

VPN session establishment is a multi-step process where the client and NetScaler exchange a number of control messages. To make this exchange easier to digest, let's break this into different phases:

  • Phase 1: The EPA exchange

  • Phase 2: The authentication exchange

  • Phase 3: Post login exchange

Note

To avoid duplication, we will assume the SSL handshake was successful. SSL handshake troubleshooting would be exactly the same as covered in the SSL section of Chapter 2, Traffic...