Setting Up DHCP Server on CentOS

5 min readApr 8, 2024

A DHCP (Dynamic Host Configuration Protocol) server automates the process of assigning IP addresses and other network configuration settings to devices on a network. In this guide, we’ll walk you through the steps to install and configure a DHCP server on CentOS.

Step 1: check the ip, netmask and broadcast.

ifconfig

Step 2: Installing DHCP Server

Install the DHCP server package using the following command:

sudo yum -y install dhcp

Step 3: Configuring DHCP Server

Copy the sample configuration file as a starting point:

sudo cp /usr/share/doc/dhcp-4.2.5/dhcpd.conf.example /etc/dhcp/dhcpd.conf

Open the main configuration file and define DHCP server options:

sudo nano /etc/dhcp/dhcpd.conf

change the following:

uncommand the line 18
aunthoritative

command the line 27,28,32,33,34,35,40,41,42,43,44,49,50,62,63,64,65,66,75,76,77,78,85,86,87,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104.

line 47 add yoursubnet and yournetmask
subnet (yoursubnet) netmask (yournetmask) {

line 48 add youriprange
range (youriprange);

line 51 add yourgateway
option routers (yourgateway);

line 52 add yourbroadcastaddress
option broadcast-address (yourbroadcastaddress);

After change the con.f file should be like this (this is my con.f file)

#dhcpd.conf
#
# Sample configuration file for ISC dhcpd
#

# option definitions common to all supported networks...
#option domain-name "example.org";
#option domain-name-servers ns1.example.org, ns2.example.org;

default-lease-time 600;
max-lease-time 7200;

# Use this to enble / disable dynamic dns updates globally.
#ddns-update-style none;

# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
authoritative;

# Use this to send dhcp log messages to a different log file (you also
# have to hack syslog.conf to complete the redirection).
log-facility local7;

# No service will be given on this subnet, but declaring it helps the 
# DHCP server to understand the network topology.

#subnet 10.152.187.0 netmask 255.255.255.0 {
#}

# This is a very basic subnet declaration.

#subnet 10.254.239.0 netmask 255.255.255.224 {
  #range 10.254.239.10 10.254.239.20;
  #option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;
#}

# This declaration allows BOOTP clients to get dynamic addresses,
# which we don’t really recommend.

#subnet 10.254.239.32 netmask 255.255.255.224 {
  #range dynamic-bootp 10.254.239.40 10.254.239.60;
  #option broadcast-address 10.254.239.31;
  #option routers rtr-239-32-1.example.org;
#}

# A slightly different configuration for an internal subnet.
subnet 192.168.108.0 netmask 255.255.255.0 {
  range 192.168.108.1 192.168.108.100;
  #option domain-name-servers ns1.internal.example.org;
  #option domain-name "internal.example.org";
  option routers 192.168.108.1;
  option broadcast-address 192.168.108.255;
  default-lease-time 600;
  max-lease-time 7200;
}

# Hosts which require special configuration options can be listed in
# host statements.   If no address is specified, the address will be
# allocated dynamically (if possible), but the host-specific information
# will still come from the host declaration.

#host passacaglia {
 # hardware ethernet 0:0:c0:5d:bd:95;
  #filename "vmunix.passacaglia";
  #server-name "toccata.fugue.com";
#}

# Fixed IP addresses can also be specified for hosts.   These addresses
# should not also be listed as being available for dynamic assignment.
# Hosts for which fixed IP addresses have been specified can boot using
# BOOTP or DHCP.   Hosts for which no fixed address is specified can only
# be booted with DHCP, unless there is an address range on the subnet
# to which a BOOTP client is connected which has the dynamic-bootp flag
# set.
#host fantasia {
 # hardware ethernet 08:00:07:26:c0:a5;
  #fixed-address fantasia.fugue.com;
#}

# You can declare a class of clients and then do address allocation
# based on that.   The example below shows a case where all clients
# in a certain class get addresses on the 10.17.224/24 subnet, and all
# other clients get addresses on the 10.0.29/24 subnet.

#class "foo" {
 # match if substring (option vendor-class-identifier, 0, 4) = "SUNW";
#}

#shared-network 224-29 {
#  subnet 10.17.224.0 netmask 255.255.255.0 {
 #   option routers rtr-224.example.org;
  #}
  #subnet 10.0.29.0 netmask 255.255.255.0 {
  #  option routers rtr-29.example.org;
  #}
  #pool {
  #  allow members of "foo";
  #  range 10.17.224.10 10.17.224.250;
  #}
  #pool {
   # deny members of "foo";
   # range 10.0.29.10 10.0.29.230;
  #}
#}

Step 4: Starting DHCP Service

Start the DHCP service:

sudo systemctl start dhcpd

Enable the DHCP service to start automatically on system boot:

sudo systemctl enable dhcpd

Restart the Network Manager service:

sudo systemctl restart NetworkManager

Step 5: firewall configuration

firewall-cmd --add-service=dhcp --permanent
firewall-cmd --reload

Step 6: Checking DHCP Service Status

Check the status of the DHCP service to ensure it’s running:

sudo systemctl status dhcpd

Congratulations! You’ve successfully set up a DHCP server on CentOS. Your DHCP server is now configured to dynamically assign IP addresses and other network configuration parameters to devices on your network.