[root@localhost ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth0
# Advanced Micro Devices [AMD] 79c970 [PCnet32 LANCE]
DEVICE=eth0
BOOTPROTO=none
HWADDR=00:0c:29:12:45:0c
ONBOOT=yes
DHCP_HOSTNAME=localhost.localdomain
IPADDR=172.17.17.2
NETMASK=255.255.255.0
TYPE=Ethernet
GATEWAY=172.17.17.1
~
[root@localhost ~]# service network restart

[root@localhost ~]# ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:0C:29:12:45:0C
inet addr:172.17.17.2  Bcast:172.17.17.255  Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fe12:450c/64 Scope:Link
UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
RX packets:547 errors:0 dropped:0 overruns:0 frame:0
TX packets:123 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:45460 (44.3 KiB)  TX bytes:19384 (18.9 KiB)
Interrupt:67 Base address:0x2024
[root@localhost ~]#

[root@localhost ~]# mount /dev/cdrom /mnt
mount: block device /dev/cdrom is write-protected, mounting read-only
[root@localhost ~]# yum install dhcp*

[root@localhost ~]# vim /etc/dhcpd.conf
[root@localhost ~]# cp /usr/share/doc/dhcp-3.0.5/dhcpd.conf.sample /etc/dhc
dhclient-eth0.conf  dhcp6s.conf
dhcp6c.conf         dhcpd.conf
[root@localhost ~]# cp /usr/share/doc/dhcp-3.0.5/dhcpd.conf.sample /etc/dhcpd.conf

[root@localhost ~]# vim /etc/dhcpd.conf
ddns-update-style interim;
ignore client-updates;
subnet 172.17.17.0 netmask 255.255.255.0 {
# --- default gateway
option routers 172.17.17.1;
option subnet-mask 255.255.255.0;
option nis-domain "domain.org";
option domain-name "domain.org";
option domain-name-servers 192.168.1.1;
option time-offset -18000; # Eastern Standard Time
range dynamic-bootp 172.17.17.1 172.17.17.100;
default-lease-time 21600;
max-lease-time 43200;

[root@localhost ~]#

eth0: 172.17.17.17.1  255.255.255.0
eth1: 192.168.1.1  255.255.255.0
eth2: 192.168.2.1  255.255.255.0
service network restart

mount: block device /dev/cdrom is write-protected, mounting read-only
[root@localhost ~]# yum install dhcp*

[root@localhost ~]#vim /etc/sysconfig/dhcrelay
#Command line options here
INTERFACES="eth0 eth1 eth2"
DHCPSERVERS="172.17.17.2"

[root@localhost ~]#service dhcrelay start

[root@localhost ~]# vim /etc/sysctl.conf
# Controls IP packet forwarding
net.ipv4.ip_forward = 1
[root@localhost ~]# sysctl -p

[root@localhost ~]# dhclient eth0
Internet Systems Consortium DHCP Client V3.0.5-RedHat
Copyright 2004-2006 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/
Listening on LPF/eth0/00:0c:29:0a:35:35
Sending on   LPF/eth0/00:0c:29:0a:35:35
Sending on   Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7
DHCPOFFER from 172.17.17.2
DHCPREQUEST on eth0 to 255.255.255.255 port 67
DHCPACK from 172.17.17.2
bound to 172.17.17.98 -- renewal in 10526 seconds.
[root@localhost ~]#
[root@localhost ~]# ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:0C:29:0A:35:35
inet addr:172.17.17.98  Bcast:172.17.17.255  Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fe0a:3535/64 Scope:Link
UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
RX packets:2301 errors:0 dropped:0 overruns:0 frame:0
TX packets:369 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:227283 (221.9 KiB)  TX bytes:47738 (46.6 KiB)
Interrupt:67 Base address:0x2024
[root@localhost ~]#