Book Image

Linux Email

Book Image

Linux Email

Overview of this book

Many businesses want to run their email servers on Linux for greater control and flexibility of corporate communications, but getting started can be complicated. The attractiveness of a free-to-use and robust email service running on Linux can be undermined by the apparent technical challenges involved. Some of the complexity arises from the fact that an email server consists of several components that must be installed and configured separately, then integrated together. This book gives you just what you need to know to set up and maintain an email server. Unlike other approaches that deal with one component at a time, this book delivers a step-by-step approach across all the server components, leaving you with a complete working email server for your small business network. Starting with a discussion on why you should even consider hosting your own email server, the book covers setting up the mail server. We then move on to look at providing web access, so that users can access their email out of the office. After this we look at the features you'll want to add to improve email productivity: virus protection, spam detection, and automatic email processing. Finally we look at an essential maintenance task: backups. Written by professional Linux administrators, the book is aimed at technically confident users and new and part-time system administrators. The emphasis is on simple, practical and reliable guidance. Based entirely on free, Open Source software, this book will show you how to set up and manage your email server easily.
Table of Contents (15 chapters)
Linux E-mail
Credits
About the Authors
About the Reviewers
Preface

Securing plaintext mechanisms


We already noted that SMTP AUTH using plaintext mechanisms isn't really safe because the string that is sent during authentication is merely encoded and not encrypted. This is where Transport Layer Security (TLS) comes in handy because it can shield the transmission of the encoded string from curious eyes.

Enabling Transport Layer Security

To enable TLS you must generate a key pair and a certificate, and then alter the postfix configuration to recognize them.

To generate an SSL certificate, and to use SSL, you need to have the OpenSSL package installed. This will be installed in many cases, otherwise use your distribution's package manager to install it.

To create a certificate, issue the following commands (as root):

This will create certificates in /etc/postfix/certs called smtpd.key and smtpd.crt. Add the smtpd_use_tls parameter to main.cf and set it to yes:

smtpd_use_tls = yes

Then you will need to tell smtpd where it can find the key and the certificate...