Linux Companion for System Administrators

Author: Jochen Hein



Publisher: Addison-Wesley

Reviewed by: Roger Burton-West

Linux Companion for System Administrators (second edition): Jochen Hein, Addison-Wesley, 0-201-67525-0, 574pp (softcover)

The Linux Companion is positioned, according to the back cover, for "anyone who wants to get more out of their Linux box"; and "will help the experienced Linux user attain a more efficient level of system administration". However, in practice it seems to be aimed much more at the beginning Linux user; in general, only one way of performing any given task is covered in detail, with only the briefest mention of alternatives that might be more effective in particular situations.

The book opens with a quick review of Linux distributions, mentioning only the positive points of each. It continues with a chapter on the layout of files on a Linux system (with side notes on RAID, deletion of temporary files, and man page categories); these are all things with which the experienced Linux user will already be familiar, but which could well be useful to a novice. Next is an analysis of the Linux boot process, with notes on LILO configuration as well as a brief discussion of other boot loaders.

After this, there is no particularly clear progression of topics; this is a book to be used as a reference for a particular situation, not to be read through. There are chapters on the X window system, backups, Emacs (which the author favours), localisation, text processing tools, emulators, shell use, and then a slew of network-related material. Much of this is at a very introductory level - "this is what a domain name is", "this is what inetd does", and so on. While this is adequate for normal configuration and operation, it does not give sufficient information to be of use when troubleshooting. There are also some surprising omissions: Emacs gets a substantial chapter, but vi is barely mentioned. The programming tools chapter quite reasonably advocates the use of a revision control system for all changing files, configuration files as well as program code; but it goes into detail only on the workings of rcs, rather than the very much more common cvs.

The networking chapters are the meat of the book. After an introductory section (Ethernet cabling, how IP addresses work and how to configure interfaces), a series of chapters deals with network protocols in broad groups. Telnet is mentioned and deprecated in favour of ssh; however, the r tools (rsh, rcp and so on) are covered in some detail with little mention of the major security risks they carry with them. Similarly, NFS is described, but while the drawbacks of attempting file locking are described, no mention is made of the many problems of privacy and security that NFS introduces. The only anonymous ftp server described in detail is wu-ftpd, again with no mention of its security problems (or the existence of sftp). NetWare support and Samba are touched on very briefly, both client- and server-side; DNS is mentioned in more detail (bind8 only), but again does not mention precautions such as chroot use. (One wonders how many Linux administrators will need to run DNS servers, compared with web or email servers - which are not mentioned at all in this book.)

Overall, this book tries to do too much: while being agnostic as to distribution, it attempts to give an introduction to all the standard Linux programs and services. This is not achieved, due to the lack of comment on web services and some others (smtp, ntp, openssl for https and other services, ssh extensions); meanwhile, the attempt to do so means that even in this substantial volume very little coverage can be given to each section. The information starts with the basics and rarely gets beyond this level; this would be a reasonable book to accompany a system installation guide for a new Linux user, but it is certainly not for "the experienced Linux user".

The first edition of this book was published in 1996, when Linux was much less widely-known than it is now and security was perhaps less of a concern. This unfortunately shows; there is very little mention of the security implication of running particular services, and no suggestion (odd in a book for system administrators) that the system needs to be kept up to date with bug-fixes.

The book was written in German, and while the translation is good, it is stilted at times; however, this does not detract from the value of the book, nor does it render technical points unclear.

In summary, this book would find its place on a novice user's shelves; it would be supplemented by a security guidebook and introductions to firewall, web and email server configuration. For the more experienced user, it could serve as an introduction to some of the less well-known functions of a standard Linux system, but it will not be of assistance in areas with which the user is already familiar.