DHCP Server in Linux

Setting Up a DHCP Server in Linux

Step 1: Install DHCP Server

For Ubuntu/Debian:

Update the package

sudo apt update

Install the ISC DHCP server package

sudo apt install isc-dhcp-server

For CentOS:

Update the package

sudo yum update

Install the DHCP server package

sudo yum install dhcp

Step 2: Configuration of DHCP Server

After successful installation, the next step is to configure the DHCP server according to our requirements.

sudo nano /etc/dhcp/dhcpd.conf

subnet 192.168.1.0 netmask 255.255.255.0 {
    range 192.168.1.100 192.168.1.200;
    option routers 192.168.1.1;
    option domain-name "mydomain.local";
    option domain-name-servers 8.8.8.8, 8.8.4.4;
    default-lease-time 600;
    max-lease-time 7200;
}

• subnet: Specifies the subnet and netmask of your network.
• range: Defines the range of IP addresses available for lease.
• option routers: Sets the default gateway IP address.
• option domain-name: Specifies the domain name for the network.
• option domain-name-servers: Configures DNS server addresses.
• default-lease-time and max-lease-time: Set the lease durations in seconds.

Save changes and close the text editor.

Step 3: Configure Network Interfaces

You must specify which network interface the DHCP server should listen on before allocating IP addresses. To list available interfaces, use the ifconfig or ip add commands.

sudo nano /etc/network/interfaces

The DHCP server interface can be configured by adding the following lines. Change eth0 to the name of your actual network interface, and change 192.168.1.1 to the IP address you want for your server:

# DHCP Server Interface Configuration
auto eth0
iface eth0 inet static
    address 192.168.1.1
    netmask 255.255.255.0

Save changes and close the text editor.

Step 4: Start and Enable DHCP Server

Start the DHCP server

sudo systemctl start isc-dhcp-server

Enable the DHCP server to start at boot

sudo systemctl enable isc-dhcp-server

Step 5: Firewall Configuration

sudo ufw allow in on eth0 to any port 67 proto udp
sudo ufw allow out on eth0 to any port 68 proto udp

Step 6: Verify DHCP Server

Check the status of the DHCP server service to ensure it's running

sudo systemctl status isc-dhcp-serve

Monitor the DHCP server logs

tail -f /var/log/syslog

Frequently Asked Questions

Is DHCP Secure?

There are no robust security mechanisms built into DHCP itself. To reduce security risks, best practices call for securing the DHCP server, employing DHCP relay agents, and putting DHCP snooping into practice.

What is a DHCP Superscope?

When a single DHCP server is responsible for providing services to several logical subnets, a DHCP superscope is employed. It enables the server to control IP allocations for various subnets.

Can I Use DHCP in Conjunction with DNS?

Yes, DHCP and DNS (Domain Name System) frequently cooperate. Client devices can resolve domain names to IP addresses by using DNS server addresses that DHCP can supply to them.

Conclusion

In this article, we learn about DHCP servers in Linux. We also learn about the DHCP protocol. We concluded the article by setting up DHCP Server in Linux.

To better understand the topic, refer to 

• Linux - Networking 
• Linux - Commands List 
• DHCP Interview Questions
   

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