vpnsite.net

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Virtual private networks (VPNs) based on the Internet instead of the traditional leased lines offer organizations of all sizes the promise of a low-cost, secure electronic network. However, using the Internet to carry sensitive information can present serious privacy and security problems. By explaining how VPNs actually work, networking expert Jon Snader shows software engineers and network administrators how to use tunneling, authentication, and encryption to create safe, effective VPNs for any environment. Using an example-driven approach, VPNs Illustrated explores how tunnels and VPNs function by observing their behavior on the wire. By learning to read and interpret various network traces, such as those produced by tcpdump, readers will be able to better understand and troubleshoot VPN and network behavior.Specific topics covered include: *Block and stream symmetric ciphers, such as AES and RC4; and asymmetric ciphers, such as RSA and EIGamal *Message authentication codes, including HMACs *Tunneling technologies based on gtunnel *SSL protocol for building network-to-network VPNs *SSH protocols as drop-in replacements for telnet, ftp, and the BSD r-commands *Lightweight VPNs, including VTun, CIPE, tinc, and OpenVPN *IPsec, including its Authentication Header (AH) protocol, Encapsulating Security Payload (ESP), and IKE (the key management protocol) Packed with details, the text can be used as a handbook describing the functions of the protocols and the message formats that they use. Source code is available for download, and an appendix covers publicly available software that can be used to build tunnels and analyze traffic flow. VPNs Illustrated gives you the knowledge of tunneling and VPN technology you need to understand existing VPN implementations and successfully create your own.

Customer Reviews

Review date : 2006-08-17
VPNs Illustrated is a great book for those wishing to understand network traffic at the packet level. Author Jon C. Snader was inspired by the earlier TCP/IP Illustrated volumes, and tries to reproduce the Tcpdump-style material found in Stevens’ classics. The level of detail found in VPNs Illustrated easily outweighs any problems this book might suffer, so I recommend you read it for in-depth knowledge of VPN traffic.

The book is divided into three parts. Of these, I found Part I ("Background") to be of questionable value. The introduction (ch 1) should not have been a chapter, and ch 2 ("TCP/IP Overview") should be replaced by a reference to existing volumes on TCP/IP. The crypto overview (ch 3) could also be replaced by a reference to other books, although as a non-crypto guy I found it a helpful refresher. The last chapter in part 1 finally gets to more subject-specific information, covering PPP, IP-in-IP, PPPoE, GRE, PPTP, L2TP, and MPLS tunnels. I really liked reading the author’s criticisms of certain protocols like PPTP and L2TP. He should have included Tcpdump traces of MPLS, since the other protocols featured packet data.

Part II included chapters on VPNs (ch 5), SSL (ch 6), SSH (ch 7), and "lightweight" VPNs (ch like VTun, CIPE, Tinc, and OpenVPN. Some of this material is very deep and probably unnecessary for most readers. The author explains messages exchanged by almost all of these protocols, which is information I’ve not seen elsewhere. Some may consider these descriptions obscure, while others (probably researchers and developers) will appreciate the analysis.

Part III covers IPSec. Ch 9 ("IPSec") should be part of ch 10 ("IPSec Architecture"). The remaining sections thoroughly address IPSec (11: AH; 12: ESP; 13: IKE; 14: the future of IPSec). I think chapters 10-13 are the best IPSec material I’ve read. They made more sense than others I’ve seen, although the complexity of IKE made ch 14 difficult to follow.

Throughout VPNs Illustrated, the author is not shy about sharing criticisms of various protocols. This is extremely valuable. He also repeats sound advice on practices to avoid (like static preshared keys) or measures to consider (defeating replay attacks). Because he illustrates so many protocols, he compares and contrasts them to emphasize key points. He also frequently cites authoritative sources like Schneier and Ferguson.

To achieve a fifth star in a second edition, I would like to see the author incorporate my previous suggestions. I would love to see configuration files for all of his examples in the appendices. He can move existing examples out of the main text to improve readability. Every protocol should have a corresponding network trace analysis, and the traces should be posted on a Web site. I would also like to see a summary of his thoughts on what makes a great VPN protocol, and then his ratings for various implementations.

You won’t necessarily be able to implement the VPN software discussed in VPNs Illustrated by simply reading the text. You will gain a great understanding of how they work, or sometimes, don’t work!

Review date : 2005-12-02
I bought this book aiming to gain indepth understanding of VPN technology, but I was disappointed. The key chapter 4, for example, try to explain tunnel concept left and right, but it mixed the general encapsulation and tunnel, and the verbose wording didn’t make it any clear. Using tcpdump trace to explain some of the field is both a blessing and curse, depending on how you look at it - I think the book is sort of strong in specific details but weak in overall conceptual pictures - however most of those details have been better documented in the RFCs.

Another example - when talking about generic tunnel skeleton using FreeBSD as example (ch 4.8), where some code snippets are presented, I feel some background and detailed illustration of flow/drawing is necessary to clear up the concept and why it correlates prevoius sections, but none given.

It may sound a bit harsh: though the author try to emulate Rich Steven’s style and dedicate the book to him, but it is hard for me to say the end product can really live up to Steven’s standard.

Review date : 2005-11-23
NOTE: This book is not for everyone, if you have not invested at least 40 hours looking at network traffic, I would recommend you pass.

This book is zero fluff, it makes you want to spin up your scratch boxes and follow along. In fact I did just that, I have to switch to a new ISP that requires PPoE and I was always curious how that worked, the book gave me just enough of a clue to interpret what was passing in and out of my house.

The world has a new grandmaster of tcpdump and I have seem some pretty good ones over the years. Once I designed a T-shirt for a SANS conference with the hexadecimal output from a tcpdump; only we flipped it so it was running down the shirt and rendered in green, to resemble the matrix.

The packet was a DNS reply. In the additional records we said good things about SANS; after all, gotta market to eat. There was an error intentionally placed into the shirt and we designated a prize for the first attendee to find the error. A student walked by wearing the shirt and the "4500" in the hex field caught one of the instructor’s eye. She followed him around murmuring, it is sideways, UDP, DNS, a reply, there are additional records, wait a minute that pointer entry is wrong. We watched in amazement, when she was done and looked up, the entire SANS faculty bowed to her. Because a mal-formatted packet can kill a packet analyzer the world needs people like Judy and Jon.

This is not a beginner book and Jon expects you to catch the 4500 stuff pretty fast. However, if you have followed the discipline of tcpdump instead of some packet analysis tool that spells out everything this book can take you to the next level.

VPNs Illustrated is rich in diagrams, including packet headers and state diagrams, examples of network traffic, and cartoons that explain the architecture of the system, or network. It is amazingly well edited, my only nit is on page 93, line 1 spacing off by one character.

The book has a strong linux bias, if you are a Windows person, you will be able to follow along for about 60% of the book using Windump, but you will not be able to use the tools or source.

This is the perfect reference for the person that knows networking and wants to really invest in taking it to the next level.

Finally, the dedication to Rich Stevens was over the top and heartfelt appreciated. I will never forget the man who taught me how to read a packet.

Review date : 2005-11-16
Given the complexity of VPN I was hoping to find a book that could explain key technologies in a concise and an organized manner. "VPNs Illustrated" does contain a wealth of technical information, but it failed on both counts.

The book offers unnecessary detail when trying to explain key concepts. It is so disjointed that the author is reduced to constantly referring the reader to other chapters to find information that is needed to understand a specific topic area. For example, the critical topic of IPSec is first introduced during a discussion of L2TP.

The book contains factual errors such as a typo describing "OC4" when the author meant to say OC48.

Overall, I was very disappointed with this text. It needs to be proofread and completely reorganized.

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