Open Source Software: Implementation and Management

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7

Open Source Server Applications

The important open source server applications, which will be discussed in

the following sections include:



Infrastructure services

 Web servers

 Database servers



Mail servers

 Systems management services

7.1 Infrastructure Services

Infrastructure services consist of basic network services, security services,

and file, print, and directory services.

Basic network services include DHCP, DNS, and WINS plus caching

services, and routing where that is not done by an appliance. It is typically

very inexpensive to provide these services, on the order of $100 per user

per year, and this is a commodity activity that any server should be able to

perform.

Security services include firewalls, virtual private networking, intrusion

detection, antivirus services, authentication, and authorization. These serv-

ices are difficult to distinguish at times from basic network services and

directory services, which support them, or even mail services, such as the

case of antivirus and antispam services. Active Directory, for example, pro-

vides directory and security services through the same product and the same

interface. Sometimes, indeed increasingly often, these are provided by

appliances.

146 7.1 Infrastructure Services

A major difference between open source and Windows in this area is

that Linux is usually the operating system of dedicated appliances. Security

is actually the most common single use of Linux in the enterprise, and this

is mostly in appliances. Appliance vendors prefer Linux (or FreeBSD) for

two reasons:

 They pay no licensing fees.

 They can tune the system precisely for their needs.

As a result, these appliances are inexpensive because of the custom foot-

print and low license fee. Linux networking appliances are also generally

very fast. Linux (along with FreeBSD) is generally recognized to have the

fastest networking stack, and the code can be further tuned for particular

dedicated purposes. Microsoft offers support for appliances also but usu-

ally prefers a more integrated approach, where Windows systems run a mix

of services on a larger server.

7.1.1 File and Print Services

In a mixed environment, we will generally use Samba for file and print ser-

vices. Linux systems also support file sharing very efficiently and easily using

NFS and FTP, and this is a good choice in existing UNIX environments.

Another choice is the Novell iFolders technology, which was recently open

sourced. Given the current distribution of servers and clients, most organiza-

tions are currently using Windows networking, and adopting Samba will be

the simplest choice.

Samba allows non-Windows systems to share file and print services

with Windows systems. Samba clients function like Windows clients, but

for Linux, Mac, or other operating systems, so they see file shares and

printers published by Windows or Samba servers. Samba servers function

like Windows servers, but on Linux or other systems, so they can publish

file and printer shares and also authenticate users in a way similar to a

Windows server. The current version of Samba can authenticate by acting

as a Windows NT primary or backup domain controller, by accessing

Windows NT domain controllers, or by accessing the Windows 2000

Active Directory.

Samba is an efficient program and scales well. Companies such as Bank

of America and Hewlett-Packard use Samba to support many thousands of

clients. The program, written by Andrew Trumbull while at SGI, is an