Slashdot Mirror
Implementing CIFS
It is one thing to be able to use Samba, Windows, and the Common Internet File System (CIFS) protocol. It is another thing entirely to understand CIFS with sufficient depth to begin coding using it. This is where Christopher Hertel's Implementing CIFS begins.
This thick book (over 600 pages) begins with a history of NetBIOS in the DOS era. It quickly progresses to NetBIOS over TCP/IP (which evolved into the current CIFS protocol). Hertel documents the beginnings of quirks that will last throughout the life of the protocol. There is an RFC that was proposed in 1987, but many vendors have added extensions to this. (It might surprise you to learn that Samba has added extensions, which are covered in Chapter 24).
After the basic overview, he quickly dives into real coding of an actual (though simple) implementation. This will be his style for the rest of the book (except for humorous asides now and then). An aspect of the protocol, such as Name Resolution, will be explained in some detail, and then expounded in actual code (and in a few cases pseudocode).
The detail is good but not overwhelming. Some people (with names like Jerry Carter or Andrew Tridgell) will want more depth than this book provides, but for with a protocol as varied as CIFS, choices have to be made. As the Samba website mentions, this book is written in "Geekish." The book covers aspects of older and newer SMB/CIFS implementations, including a description of the NTLM2 challenge/auth system.
One thing that should be noted is that the code examples work, but as the author points out, they usually have little or no error handling. This is common to many books, but it is something to remember.
Now, should you get this book? If you're just a user, you probably don't need it. But if you've ever wished you could understand the Samba technical mailing list, or wanted to know why it takes up to 15 minutes to see a new machine, then you'll enjoy this book. If you want to utilize CIFS in any manner (even if just implementing Samba for clients), I'd highly recommend reading this. It will help you to understand what is going on on your network, even if you're not writing the code yourself. And if you want to be a Samba coder, it is required reading.
What didn't I like? I first read the book in an airport, and found that it relies heavily on having access to a computer. I would have preferred more explanations of code fragments than was given. However, this is a minor issue; most people who are implementing CIFS will be using a computer! I was also left with a desire for more information, but the large Appendix D along with many sources recommended provide for further study.
As a bonus, Appendix A tells you how to make a good cup of Earl Grey tea! That alone to some would be worth the price of admission.
You can purchase Implementing CIFS from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
Maybe a bit offtopic, but on my network I notice that Windows machines in the Network Neighborhood are slower to access than samba shares on linux machines. Go figure.
Linux Resources
And best of all it's available on O'Reilly's Safari service.
The usual cause is badly synced browse lists.
If you add a samba server and tell it to run WINS (with wins=yes), and then tell EVERY windows machine that the wins server is at (IP address of Samba Server), things usually speed up considerably.
Also, there is (I believe), a C:\winnt\system32\drivers\etc\lmhosts file that works as a hosts file for WINS).
Fellowship 9/11
This book is simply the best reference available for CIFS. I only say that because I have spent $$$ getting everything on the subject I can. With the recent changes in Microsoft licensing every sensible IT professional should be exploring alternatives. A SAMBA server is a great alternative. This book is all you need to go from knowing next to nothing to knowing enough to impress your geeky Network Admin friends.
This book is well written, clear and expansive. I didn't read it cover to cover (not at first anyway) I found pieces I needed, applied it, digested it, reviewed it and then went on to the next morsel I needed. If I missed something it was easy to find. By the way, it works with Win2K and WinXP neither of which is well documented by anyone anywhere.
The full text of the book is available online as well; I don't want to slashdot the site, but google for "implementing cifs".
Can't we just let CIFS to die, already? As long as people are still running Windows and Windows is still using CIFS, it will be necessary to support CIFS for Windows interoperability. No argument from me that it is a horrible protocol for file sharing; but then NFS isn't much better.
"Freedom means freedom for everybody" -- Dick Cheney
For what purpose? Ruby is an esoteric language that hardly anyone uses and less people will use as the years goes on. This means that the code base will be unmaintainable.
Now Java or C# is a real option. Microsofts next implementation will be written in C# as a matter of fact.
Exactly the point I was trying to make above.
As much as the slashdot crowd would probably hate to admit that Microsoft got something right, SMB/CIFS is the 'killer app' for sharing files and printers over a LAN.
If there's another application that does the same job as SMB/CIFS and is:
- Free
- easy to use client
- easy to configure server
- multiplatform - Windows, OS X, varying strains of Unix, and linux
then bring it on. Until then, we're stuck with CIFS.Thanks
Bruce
Bruce Perens.
Replace it with nfs unix file sharing maybe? Oh I forgot. We're talking about Windows here. God forbid Microsoft should support nfs. It's not as if it's better than smb or anything and it's not as if Mac and the rest of the Unix world already support it
You're right, I wouldn't steal a car. But if it were possible, I sure as hell would download one!
However, I did need the sniffer method of reverse engineering for much of what the book did not cover. One complaint I had is that I needed more information on the higher level protocols such as LANMAN for handling printer queues and this information was either non-existent or schetchy in the book. Although the book is long, much of it is taken up by a CIFS document which you could download for free on the internet. So I do think that the description part of the book could be more extensive (Sorry Chris). Maybe in the next revision.
You might ask why I was implementing CIFS from scratch? Its a valid question, since Samba would/should be anyone's implementation of choice. I did it because we are developing a printer which is not GPL (and unfortunately not based on Linux). We are not using any GPL code in it, and so this was really the only choice besides buying it from someone (but where's the fun in that). I am planning on releasing this code under a BSD license, but it's not ready for prime time yet and I need to get back to it (in a couple of months).
So this was a really good book for CIFS implementors, but how many of those could there be?
One thing that should be added to that document is that all the Win9x machines should have the ability to be a Master Browser disabled (so long as there's at least 1 NT machine on the net).
Otherwise, eventually one of the 9x machines with think it's won the browse election even when that should be impossible. This screws the network neighborhood. Very longstanding bug going back to WfW. You can check the state of your network using the "browstat" tool that comes with the resource kit.
(Also, yer correct that NetBIOS or IPX will be faster than NBT for whatever reason. Make sure to adjust the "binding order" so that these protocols come ahead of TCP/IP. Can't recall exactly how to do this, sorry.)
This might not be realistic for a home net, but install WINS/DHCP if possible and put the clients into p-mode. (no NetBIOS broadcasts)
Download Windows Services for UNIX for free from Microsoft, it contains a NFS client and server. I use this on my home network, no more Samba and its confusing config file (even with SWAT it is a nightmare). You can even choose to just install the nfs services and continue to use Cygwin for the rest of your Unix-on-Windows goodness.
When you lose something irreplaceable, you don't mourn for the thing you lost, you mourn for yourself. - Harpo Marx
Bruce
Bruce Perens.