Red Hat Enterprise Linux 5 Administration Unleashed

552APPENDIX DTroubleshootingQ. I didn’t set my hostname during installation, and my DHCP server doesn’t set it forme. How do I configure a hostname for my system?A. As the root user, edit the HOSTNAME line in the /etc/sysconfig/network file. Sets itsvalue to the desired hostname. This value is only read at boot time. To change thehostname immediately, execute the command hostname as the rootuser.Q. I modified my boot parameters as described in Chapter 2, “Post-InstallationConfiguration.” How do I verify that the boot parameter was used?A. Use the command cat /proc/cmdline to view a list of options passed to the kernelat boot time.Q. The first time my system booted after installation, the Setup Agent asked whether Iwanted a firewall. I enabled it at the time. Now, I want to write my own custom firewalland need to disable the default firewall. How do I disable it?A. Select the System menu from the top panel of the desktop and then selectAdministration, Security Level and Firewall. Enter the root password if prompted.The same interface used in the Setup Agent is displayed. Select Disabled from thepull-down menu, and then click OK. The changes take place immediately. Refer toChapter 24, “Configuring a Firewall,” if you need help writing custom firewall rulesusing IPTables.Q. I received an email alert stating that some of the GFS packages have been updated.When I try to use Yum to update them, it says no updates are available. How do Idownload and install the updates?A. Most likely, the system is not subscribed to the RHN software channel that providesthe packages and updated packages for GFS. Log in to your RHN account atrhn.redhat.com, and make sure the system is subscribed to the correct channel. Thechannel containing the GFS packages will be a child channel of the Red HatEnterprise Linux parent channel.Q. After installing Red Hat Enterprise Linux as a guest OS in a VM using theVirtualization feature, the installation program says it is going to reboot, but thesystem shuts down and never comes back up. How do I start the VM again?A. To start the VM after installation (and any time the VM is shutdown), execute thefollowing command as root, where is the unique name given to the VMduring setup:xm create -c Even if you are using the Virtual Machine Manager graphical program, thiscommand must be performed on the command line. As of the initial release of RedHat Enterprise Linux 5, the Virtual Machine Manager interface does not allow theVM to be started.