Red Hat Enterprise Linux 5 Administration Unleashed

320CHAPTER 14Granting Network Connectivity with DHCPAllowing ConnectionsBy default, the DHCP server listens for requests on UDP port 67. Verify that your firewallsettings allow incoming requests from this port.NOTEIf the local-port parameter (discussed in the next section) is used in the configurationfile to change the port number, adjust your firewall settings for the defined portinstead.If custom IPTables rules are being used, refer to Chapter 24, “Configuring a Firewall,” fordetails on how to allow these ports.If using a default security level in Red Hat Enterprise Linux, use the Security LevelConfiguration tool. Start it by selecting Administration, Security Level and Firewallfrom the System menu on the top panel of the desktop or by executing the systemconfig-securitylevelcommand. Enter the root password when prompted if running asa non-root user. In the Other ports area, click Add to specify the DHCP port. After addingthe port, it appears in the Other ports list as shown in Figure 14.1.FIGURE 14.1Allowing DHCP RequestsConfiguring the ServerTo configure a Red Hat Enterprise Linux system as a DHCP server, the dhcp RPM packagemust be installed. If it is not installed, use Red Hat Network to install it as discussed in