Red Hat Enterprise Linux 5 Administration Unleashed

CHAPTER 14Granting NetworkConnectivity withDHCPIN THIS CHAPTER. Allowing Connections. Configuring the Server. Logging ConnectionsDHCP, or Dynamic Host Configuration Protocol, allows anadministrator to configure network settings for all clients ona central server. The DHCP clients request an IP address andother network settings from the DHCP server on thenetwork. The DHCP server in turn leases the client an IPaddress within a given range or leases the client an IPaddress based on the MAC address of the client’s networkinterface card (NIC). If an IP address is assigned according tothe MAC address of the client’s NIC, the same IP address canbe leased to the client every time the client requests one.DHCP makes network administration easier and less proneto error. For example, when network settings or the IPaddress range of a network changes, instead of changingthe configuration files on each client, the administratorsimply changes the configuration on the DHCP server andapplies the changes. If your network consists of hundredsof clients, it is easy to see the benefits.From the user’s point of view, DHCP can be useful formobile computing. If a laptop is configured to use DHCPfor its network settings, it can easily move from onenetwork to another without reconfiguration or user interventionas long as the network includes a DHCP serverwith an available IP address for the laptop.NOTEIf SELinux, a mandatory access control securitysystem, is enabled, the default targeted policyprotects the DHCP daemon. Refer to Chapter 23,“Protecting Against Intruders with Security-EnhancedLinux,” for details.