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C H A P T E R 10
Configuring Ubuntu Server
As a Mail Server
Sending and Receiving
Mail Easily
One of the most common functions of a Linux system is to serve mail. Several
Linux-based mail server programs are available for this purpose. Several programs are
available to accomplish this task. In this chapter you will learn what is necessary to build
a solution to send and receive e-mail on a network. Because Ubuntu Server uses the
Postfix mail server by default to send mail to other networks, this chapter covers Postfix.
Different solutions are available to allow users to connect to their mailboxes to fetch mail.
One of the easiest to use of these solutions is Qpopper, so that is the solution of choice in
this chapter.
Understanding the Components of a Mail Solution
If you want to understand what is needed to build a mail server that can handle e-mail for
a complete network, you need to understand the three different agents that are used to
process Internet e-mail:
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C H A P T E R 11
Managing Ubuntu Server
Security
Configuring Cryptography and
AppArmor
Ubuntu Server offers some powerful security options. In this chapter you’ll learn how
to set up two important security solutions. First, you’ll learn how to create and manage
a PKI environment and certificate authority, using OpenSSL cryptography. Next, you’ll
be introduced to AppArmor, a new feature in Ubuntu Server 8.04 that helps you to secure
individual applications.
Managing Cryptography
In the age of the Internet, cryptography has become increasingly important. When data is
sent across insecure networks, you need to make sure the data is protected. When com-
municating with a host on the other side of the world, you need to make sure that the
host really is the host you think it is (authentication). To do this, cryptography can help.
In this section you will learn how to use OpenSSL to implement a secure cryptographic
infrastructure. The following subjects are discussed:
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