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

NTLM SSO (401 Based Authentication)


NTLM (NT LAN Manager) is a Microsoft protocol which is still very frequently used in web server authentication scenarios, especially within an enterprise. It is enabled by the use of LDAP (invariably Active Directory). When used for authentication in front of servers that use NTLM, enabling SSO on the NetScaler makes very good sense.

When NTLM SSO fails via the NetScaler, the usual User experience will be that they see two 401 dialog boxes followed by a 403 error.

NTLM Authentication flow

NTLM is a challenge-based protocol. The exchange involves the server challenging the client to prove its identity in order to be able to see the resource it is requesting.

The following screenshot is an exchange between the NetScaler SNIP and a web server that has NTLM Authentication enabled. You can filter this communication using http || ntlmssp:

Now let's examine each of the steps in more detail:

  1. First, NetScaler forwards the client's request for an object, and instead...