Topics: Networking, Red Hat / Linux

Howto Red Hat Enterprise Linux 5 configuring the network

Red Hat LogoRed hat Linux provides following tools to make changes to Network configuration such as add new card, assign IP address, change DNS server, etcetera:

  • GUI tool (X windows required) - system-config-network
  • Command line text based GUI tool (No X windows required) - system-config-network-tui
  • Edit configuration files directly, stored in /etc/sysconfig/network-scripts directory
The following instructions are compatible with CentOS, Fedora Core and Red Hat Enterprise Linux 3, 4 and 5.

Editing the configuration files stored in /etc/sysconfig/network-scripts:

First change directory to /etc/sysconfig/network-scripts/:
# cd /etc/sysconfig/network-scripts/
You need to edit / create files as follows:
  • /etc/sysconfig/network-scripts/ifcfg-eth0 : First Ethernet card configuration file
  • /etc/sysconfig/network-scripts/ifcfg-eth1 : Second Ethernet card configuration file
To edit/create the first NIC file, type the following command:
# vi ifcfg-eth0
Append/modify as follows: 
# Intel Corporation 82573E Gigabit Ethernet Controller (Copper)
DEVICE=eth0
BOOTPROTO=static
DHCPCLASS=
HWADDR=00:30:48:56:A6:2E
IPADDR=10.251.17.204
NETMASK=255.255.255.0
ONBOOT=yes
Save and close the file. Define the default gateway (router IP) and hostname in /etc/sysconfig/network file: 
# vi /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=host.domain.com
GATEWAY=10.251.17.1
Save and close the file. Restart networking:
# /etc/init.d/network restart
Make sure you have correct DNS server defined in /etc/resolv.conf file. Try to ping the gateway, and other hosts on your network. Also check if you can resolv host names:
# nslookup host.domain.com
And verify if the NTP servers are correct in /etc/ntp.conf, and if you can connect to the time server, by running the ntpdate command against one of the NTP servers:
# ntpdate 10.20.30.40
This should synchronize system time with time server 10.20.30.40.



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