Hardware manual

Chapter 2 Inside Mac OS X Server 45
If you don’t have an Internet service provider (ISP) who handles DNS for your network,
you can set up a DNS server on your Mac OS X Server. See individual service
administration guides for information about DNS dependencies for each service.
Mac OS X Server provides administration tools for service configuration management,
zone control, and monitoring, providing a graphical way to:
 Enable zone transfers and recursion
 Work with log files
 Manage zones and records for the machines in those zones
Firewall
Firewall service protects your server and its contents from intruders. It provides a
software firewall, scanning incoming IP packets and accepting or rejecting them based
on filters you define.
You can set up server-wide restrictions for packets from specific IP addresses. You can
also restrict access to individual services, such as web, mail, and FTP, by defining filters
for the ports used by the services. IP firewall can be used to block access to specific
service ports or to allow access only to certain ports.
IP firewall also provides a sophisticated mechanism, stateful packet inspection, for
determining whether an incoming packet is a legitimate response to an outgoing
request or part of an ongoing session, allowing packets that would otherwise be
denied.
NAT
NAT is a method of connecting multiple computers to the Internet (or any other IP
network) using one IP address. NAT converts the IP addresses you assign to computers
on your private, internal network into one legitimate IP address for Internet
communications. For example, the AirPort Base Station uses NAT. By default, a base
station assigns IP addresses using DHCP to computers on an Ethernet network, then
uses NAT to convert those addresses when any of the computers needs to access the
Internet.
NAT is becoming increasingly popular because it preserves IP addresses. It also
increases the security of Internet access, because it supports only connections that
originate on an internal network.
NAT is closely related to IP firewall. The firewall diverts network packets to the NAT
process so they can be translated.