Linux, Unix, /etc

Danger Will Robinson! You are now entering a condescending Unix user zone!

TCP/IP Network Administration

What This Book Means To Me

An easy way to tell how often as book has really been read is to glance at the page side of the closed volume: dirty sides == often read (or a reader who doesn't wash often enough — hmmm...). My old copy of TCP/IP Network Administration has an imprint of dust, grime and coffee stains all down this side, testimony to how often it has been consulted since I bought it back in 1994. In that first edition, the system-specific stuff spanned Solaris, BSD and SysV: narry a mention of then-humble Linux. The second edition uses Linux, Solaris and BSD, roughly in that order of importance. How times change!

Outline of the Book

The book is very concise throughout, and repays careful reading. Much of the content has not aged at all; but some has, quite severely. Thankfully, O'Reilly brought out a second edition a few years ago, and this is still pretty up-to-date. Not only is it brought up to date, but also revised, with several chapters getting a major change in focus, especially 3 & 9; app. A is new, as is D. There is an increase in size: the book is physically bigger (the new O'Reilly format), and has more pages. Except where indicated, I'm talking about this second edition. The best thing I can do here is simply take you through the chapters. See for yourself how much he covers, and how well. The book falls naturally into three parts, although it isn't so divided in the ToC. I've taken the liberty of splitting it up accordingly here. To avoid repetition, where I don't say anything about a chapter, you can take it as read that I mean: "Good stuff. All essential info. is here, concisely presented".

About TCP/IP

The first chunk of the book, three chapters long, introduces us to how a TCP/IP network actually works.

1 Overview of TCP/IP

A decent, concise introduction to TCP & IP, giving a little history of the protocol, explaining the OSI Reference Model, then looking at the implementation of these ideas in TCP/IP.

2 Delivering the Data

IP Addresses, Subnetting, Routing, all the usual suspects.

3 Network Services

Replacing the 1st ed.'s Name Service Concepts with a more general introduction which includes DNS. A definite improvement.

Building the Network

Next, we start getting our network up and running, from scratch.

4 Getting Started

5 Basic Configuration

6 Configuring the Interface

Here Hunt considers both PPP and SLIP. But why bother with SLIP at all nowadays? The space would better have been given over to more details about PPP. Not that the existing treatment isn't adequate; but some more advice about tuning would have been nice, for example.

7 Configuring Routing

8 Configuring DNS Name Service

Still the old BIND, alas! But a useful tutorial nonetheless.

9 Network Applications

This chapters covers NFS, lpd, NIS, BOOTP, DHCP, POP: short and sweet sections on each. Also, the first of the dreading screenprints rears its ugly head (see below). One point that occurs to me is that the only mention of the service switch file occurs in the NIS section. This is out of date now, for Linux at least — /etc/nsswitch.conf is an important file, controlling the implementation of certain system services such as host and user name lookup.

10 sendmail

The 1st edition chapter, after a brief introduction and a look at aliases, dropped one straight into the gristly details of /etc/sendmail.cf. I had many a happy hour struggling with this— I don't think! The 2nd ed. covers the m4 macro alternative, which anyone with any sense will be using. For me, this is *the* classic Hunt chapter. Nice blend of old and new — m4 makes things easier, but its good to know what it is doing — and essential if you have custom requirements.

Running the Network

Now that the network is up, we need to know how to look after it. Two chapters, and a chunk of appendices, tell us what we need to know.

11 Troubleshooting TCP/IP

An excellent introduction to what does after all constitute the bulk of work on your average network — fixing it when it goes wrong! What tools to use, and how to use them.

12 Network Security

Perhaps the best chapter in the book. Hunt really fits a lot of essential information into a small compass, without it seeming crammed or skimpy. On the other hand, he knows when to stop, refusing to cover firewalls on the grounds that an adequate treatment is beyond the scope of the book. He goes on to say, "Unless you have skilled Unix systems administrators with adequate time, a do-it-yourself firewall installation is a mistake ... If your information is valuable enough to protect with a firewall, it must be valuable enough to protect with a professionally installed firewall". This overstates the case, I think. Firewalls are a must for any machine connected to the Net. Various "script kiddie" DoS attacks can be prevented by packet filtering, for instance, and the rules to do this are well-known (or at least, available if you go look).

13 Internet Information Resources

Why this isn't an appendix, I don't know. There is a useful guide to setting up an ftp server in here, for some reason. But, oh, dear: there are screen-prints all over the place, 7 in all, each one taking up most of the page. I do hope O'Reilly are succumbing to the lure of padding — I can see no other purpose to this stuff. But then, I have a bee in my bonnet about screen-prints... er, I'll get me coat... The Appendices have seen quite a few changes. The first two, A Network Contacts and B Forms have gone entirely, replaced by A PPP Tools . A welcome change. B A gated Reference A dhcpd Reference D named Reference E A sendmail Reference This used to be a sample sendmail.cf, and of limited use, frankly (if you can actually read that stuff, you need to get out more). The new version is much, much better. Most if not all of the reference material you are likely to need for sendmail is contained in these few pages. It really is "a sendmail reference", covering compilation from source, command line options, a comprehensive list of m4 macro definitions, and a listing of the /etc/sendmail.cf options that can be set with the m4 macros. This is really first-rate. This part alone justifies an upgrade from v1.3. F Selected TCP/IP Headers A reference for those headers referred to in the troubleshooting chapter. The first edition continued with Appendix G, a reference for passwd+, a dropin replacement for the traditional Unix password suite. With shadow passwords now in near-universal use, this has passed its sell-by date, and has been pruned.

Why This Book Is Important

The book is a guide to TCP/IP Networking under Unix: the specific Unices considered are Linux, Solaris, BSD. There are advantages and disadvantages to such a "generic Unix" approach. Hunt's book is better in the higher-level chapters, (and also in the lowest-level chapter) because of this. In areas where OS-specific information is required, he does less well. Also, it is a little *too* concise sometimes. This is not a beginners' book. In summary, TCP/IP Network Administration is a must-have. Unlike many books, the revised 2nd edition contains so many changes and so much new matter, that it's really a new book. If you're trying to work from the 1st edition, upgrading to the 2nd would be advisable. But while indispensable, the question arises, is it enough? For a Linux user, perhaps not. When the 2nd edition of Linux Network Administrator's Guide comes out, I'll do a comparative review. And they all lived happily ever after (according to Rusty).

How To Get The Book

Title: TCP/IP Network Administration
Author: Craig Hunt
Publisher: O'Reilly
ISBN: 093717582X (1st ed.); 1565923227 (2nd ed.)
Price: £22.00; $37.95
Pages: 472; 612
Date: August 1992; January 1998.

Paul Dunne 2000

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