Fedora Linux

The one entry in this file associates the system's name and the localhost alias with the loopback device (which may be expressed as ::1 in IPv6 notation, or 127.0.0.1 in IPv4 notation). This entry must exist in the file, or many system services will fail to operate.

You can add additional entries to /etc/hosts if you want to refer to local computers by name but don't want to go through the effort of setting up DNS (see Lab 7.3, 'Configuring a Domain Name Server'). Simply place the IP address at the start of the line and then list the names and aliases for that host, separated by spaces or tabs:

# Do not remove the following line, or various programs
# that require network functionality will fail.
::1 bluesky.fedorabook.com localhost
172.16.97.60 darkday.fedorabook.com darkday frank
172.16.97.73 accounting.fedorabook.com accounting susan
172.16.97.207 samba.fedorabook.com

To change the system's hostname, edit the /etc/hosts file and change the entry for the loopback line (do not remove the localhost alias):

# Do not remove the following line, or various programs
# that require network functionality will fail.
::1 beige.fedorabook.com localhost

Then edit the HOSTNAME entry in /etc/sysconfig/network :

NETWORKING=yes
NETWORKING_IPV6=yes
HOSTNAME=beige.fedorabook.com

The change will take effect next time you boot. To make the change take effect immediately, use the hostname command:

# hostname beige.fedorabook.com
# hostname
beige.fedorabook.com

3.2.1.3.4. Configuring networking from the command line using DHCP

Fedora Core provides the dhclient program to configure network interfaces based on information received from Dynamic Host Configuration Protocol (DHCP) servers. Simply run this program as root , specifying the interface(s) that you wish to configure:

# dhclient wlan0
# ifconfig wlan0
wlan0 Link encap:Ethernet HWaddr 00:0C:2D:00:2B:DB
         inet addr:10.144.12.160 Bcast:10.144.255.255 Mask:255.255.0.0
         inet6 addr: fe80::20c:2dff:fe00:2bdb/64 Scope:Link
         UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
         RX packets:3 errors:0 dropped:0 overruns:0 frame:0
         TX packets:18 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:1000
         RX bytes:1222 (1.1 KiB) TX bytes:3442 (3.3 KiB)

Since information supplied by a DHCP server is considered a lease that expires after a preset time, dhclient continues to run in the background so that it can renew the lease when necessary. If you move the machine to a new network and attempt to run dhclient again, the existing background process will be detected, and the new copy of dhclient will exit immediately without obtaining a new network configuration. To work around this problem, kill the background copy of dhclient before running it for the second time:

# killall dhclient
# dhclient wlan0

dhclient may be running even if you didn't start it manually, since boot-time network activation or activation through system-config-network or system- control-network may have launched it.

3.2.1.4. Using wireless adapters that require firmware

Fedora's distribution policies do not permit the inclusion of binary software without source code, and that includes firmware. Unfortunately, some very popular wireless network cards require firmware for which the vendor will not release source code.

The most common wireless adapter family affected by firmware issues is the Intel Pro Wireless (IPW) seriesoften integrated into systems under the Centrino moniker, but also sold as add-on units with Mini-PCI, CardBus, or USB interfaces. 

If you find that your wireless network card is not working, it is possible that a driver is present, but the firmware file is not. Use grep to search the system logfile for messages related to firmware:

# grep firmware /var/log/messages
Jun 29 04:11:57 beige kernel: usb 2-1: Failed to load zd1201.fw firmware file!
Jun 29 04:11:57 beige kernel: usb 2-1: Make sure the hotplug firmware loader is installed.
Jun 29 04:11:57 beige kernel: usb 2-1: zd1201 firmware upload failed: -2
Jun 29 04:11:57 beige firmware_helper[14394]: Loading of /lib/firmware/zd1201.fw for usb driver failed: No such file or directory

These messages clearly show that the system attempted to load firmware for a USB wireless adapter but failed because the firmware file was not found ( No such file or directory ).

To find more information, view the /var/log/messages file using a text editor or the less program, and search for the date and time identified by the previous grep command:

# less /var/log/messages
...(Lines skipped)...
Jun 29 04:11:57 beige kernel: usb 2-1: new full speed USB device using uhci_hcd and address 5