UNIX System Administration Handbook - Evi Nemeth [369]
COSTALES, BRYAN and ERIC ALLMAN. sendmail, 2nd Edition. Sebastopol, CA: O’Reilly, 1997.
This book is the definitive tome—1,000 pages’ worth. It includes a tutorial as well as a very complete reference section. The book reads well in the open-to-a-random-page mode, which we consider an important feature for a reference book. It has a good index too. The third edition is being worked on and will be out in 2000.
AVOLIO, FREDERICK M. AND PAUL A. VIXIE. Sendmail Theory and Practice. Digital Press, 1995.
Avolio and Vixie address the “why and how” of sendmail, whereas the Costales/Allman book talks more about the “what.” This 250-pager takes a high-level approach.
CLAYTON, RICHARD. “Good Practice for Combating Unsolicited Bulk Email.” RIPE/Demon Internet. 2000. http://www.ripe.net/ripe/docs/ripe-206.html
This document is aimed at ISPs. It has lots of policy information and some good links to technical subjects.
SCHWARTZ, ALAN, AND PAULA FERGUSON. Managing Mailing Lists. O’Reilly, 1998.
This book is a good reference on mailing lists.
The man page for sendmail describes its command-line arguments. See Sendmail: An Internetwork Mail Router, by Eric Allman, for an overview.
Installation instructions and a good description of the configuration file are covered in Sendmail Installation and Operation Guide, which can be found in the doc/op subdirectory of the sendmail distribution. This document is quite complete, and in conjunction with the README file in the cf directory, it gives a good nuts-and-bolts view of the sendmail system.
RFC822 describes the syntax of messages and addresses in a networked mail system, and RFC1123 describes host requirements. These are, in a sense, the functional specifications to which sendmail was built.
RFC821 defines the Simple Mail Transport Protocol (SMTP), and RFCs 1869, 1870, 1891, and 1985 extend it to ESMTP.
RFC974 describes MX records in the Domain Name System and their relationship to mail routing.
Other mail-related RFCs include:
• RFCs 1891–1894 – Delivery status notifications (bounce messages)
• RFC1985 – Remote queueing
• RFC2033 – LMTP, the Local Mail Transport Protocol
• RFC2034 – SMTP error codes
• RFC2045 – MIME extensions
• RFC2476 – MSA, Mail Submission Agent specifications
• RFC2487 – Secure SMTP over TLS
• RFC2554 – SMTP authentication
Postfix documentation and information can be found at www.porcupine.org.
20 Network Management and Debugging
Because networks increase the number of interdependencies among machines, they tend to magnify problems. As the saying goes, “Networking is when you can’t get any work done because of the failure of a machine you have never even heard of.”
Network management is the art and science of keeping a network healthy. It generally includes the following tasks:
• Fault detection for networks, gateways, and critical servers
• Schemes for notifying an administrator of problems
• General monitoring, to balance load and plan expansion
• Documentation and visualization of the network
• Administration of network devices from a central site
On a single Ethernet, it is generally not worthwhile to establish formal procedures for network management. Just test the network thoroughly after installation, and check it occasionally to be sure that its load is not excessive. When it breaks, fix it.
As your network grows, management procedures should become more automated. On a network consisting of several different subnets joined with switches or routers, you may want to start automating management tasks with shell scripts and simple programs. If you have a WAN or a complex local network, you should consider installing a dedicated network management station with special software.
In some cases, your organization’s reliability needs will dictate the sophistication of your network management system. A problem with the network can bring all work to a standstill. If your site cannot tolerate downtime, it may well be worthwhile to obtain and install a high-end enterprise network management system.
Unfortunately, even