22.12.2012 Views

Front cover - IBM Redbooks

Front cover - IBM Redbooks

Front cover - IBM Redbooks

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

A<br />

Appendix A. Debugging with a protocol<br />

analyzer<br />

While most software products include some trouble-shooting facilities (for<br />

example, most browsers allow you to “view html source” of a page), these<br />

debugging facilities usually “pre-process” the output. For example, what you can<br />

normally see using browser-based debugging tools is just the HTML contents –<br />

already expanded/resolved – and normally you are unable to see the underlying<br />

HTTP dialogs. Thus, when debugging network and security infrastructures, it’s<br />

very useful to have a tool called a “protocol analyzer” to see what is really<br />

happening behind the scenes. The goal of this appendix is to introduce a basic<br />

protocol analyzer for network troubleshooting.<br />

What is a protocol analyzer<br />

A protocol analyzer may be a stand-alone hardware device that you plug into the<br />

same network segments that you want to analyze, or more likely, just a software<br />

package you install on your workstation. These products allow one to capture<br />

network communication dialogs between computers and processes, apply<br />

different selection and filtering criteria, and display them in user-friendly formats.<br />

This includes interpreting the contents according to the protocols being spoken<br />

at the different layers (or example TCP, HTTP, HTML). Some of these tools allow<br />

you to code your own decoding modules for protocols that they may not<br />

understand “out of the box”.<br />

© Copyright <strong>IBM</strong> Corp. 2004. All rights reserved. 635

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!