Red Hat Enterprise Linux 5 Administration Unleashed

68CHAPTER 2Post-Installation ConfigurationLISTING 2.5Ethernet Interface Configuration File for DHCPDEVICE=eth0BOOTPROTO=dhcpONBOOT=yesLISTING 2.6Ethernet Interface Configuration File for Static IPDEVICE=eth0BOOTPROTO=noneONBOOT=yesNETWORK=192.168.1.0NETMASK=255.255.255.0IPADDR=192.168.1.15USERCTL=noIf the ONBOOT option is set to yes, the device is activated at boot time using the networkinitialization script.Other device names include lo for the local loopback device, pppX for dialup interfaces,and irlanX for infrared devices where X is the device number starting with 0. Refer to thefile /usr/share/doc/initscripts-/sysconfig.txt for additional options forthe files in this directory.Starting and Stopping the NetworkIf an Ethernet device is found during installation and configured, the network is configuredto start automatically at boot time unless you unchecked the Activate on bootoption for the device. To disable it at boot time after installation, use the chkconfignetwork off command. To enable it at boot time, use the chkconfig network oncommand.The /etc/hosts and /etc/resolv.conf are referenced each time they are used, so modificationsto them take place immediately. If the hostname is modified in /etc/sysconfig/network, the change does not occur until the next reboot. To immediately change thehostname, execute the command hostname as the root user at a shellprompt, replacing with the new hostname for the system.If you modify network settings in /etc/sysconfig/network-scripts/, the changes do nottake place until the network is restarted or the individual device is shut down andbrought back up. To restart the entire network (the loopback device and all networkdevices), use the command service network restart as root. To shut an individualdevice down and bring it back up, as root, execute the command ifdown and then ifup , where is the name of the device such aseth0.To stop all the network devices, use the service network stop command as root. To startthe network, use the command service network start as root.