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Dynamic Host Configuration Protocol (DHCP)

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Dynamic Host Configuration Protocol (DHCP) Meaning

What is DHCP? Dynamic Host Configuration Protocol (DHCP) is used to dynamically assign Internet Protocol (IP) addresses to each host on your organization's network. In this DHCP meaning, a host can refer to any device that enables access to a network. Some examples include desktop computers and laptops, thin clients, and personal devices, among others. DHCP ensures all of these devices get assigned an IP address.

In the context of this DHCP definition, DHCP also assigns Domain Name System (DNS) addresses, subnet masks, and default gateways. All of these enable devices to communicate with the internet and each other within the confines of your network.

How Does the Dynamic Host Configuration Protocol (DHCP) Work?

DHCP protocols send messages to devices that connect to your network, providing them with what they need to interface with essential network functions. Imagine if you have a small home network that allows your laptop, your tablet, and your phone to connect to it. If you have to assign an IP address to each one, that may not be too difficult, especially because there are only three devices.

On the other hand, assigning IP addresses, as well as subnet masks, DNS addresses, and other essential data would take far too much work and time if you have to do so for a few hundred devices. DHCP automatically provides this information to all of the devices that connect to your network.

DHCP Components

The primary DHCP components include a DHCP server, client, and relay.

DHCP Server

A DHCP server is what the system uses to automatically provide IP addresses and additional network parameters to the devices that connect to your network. It is able to provide temporary IP addresses taken from a pool of available addresses.

In addition, a DHCP server gives permanent IP addresses and DHCP configuration parameters, including those pertaining to subnet masks, default gateways, and DNS servers.

DHCP Client

A DHCP client is a device that acts as a host, and it receives the information sent from the DHCP server. This includes any device that can connect to the network and needs data from the DHCP server to interact with the network.

DHCP Relay

A DHCP relay refers to any transmission control protocol/IP (TCP/IP) host that forwards DHCP messages between servers and clients. A DHCP relay plays an essential role, for instance, when a network consists of several subnetworks. In this case, a DHCP relay enables one DHCP server to provide the necessary information to all of the clients on both the primary network and subnet.

Security Considerations for Using DHCP

To ensure your DHCP servers do not present significant risk, there are a few DHCP security-related issues to keep in mind:

1.         A DHCP server can only provide a limited number of IP addresses. This means an attacker may be able to launch a denial-of-service (DoS) attack by requesting so many IP addresses, rendering essential devices unable to connect.

2.         It is also possible for an attacker to use a false DHCP server to provide fraudulent IP addresses to the clients on your network.

3.         Users that get an IP address also get the DNS address—meaning, it is possible they can obtain more data than they should from those servers. It is best to limit the access that people have to your network, as well as use firewalls and secure connection tunnels via virtual private networks (VPNs).

Protection Against DHCP Starvation Attack

A DHCP starvation attack involves a malicious actor inundating a DHCP server with requests for IP addresses until it cannot provide any more. This puts the hacker in a position to deny requests from authorized network users, as well as set up an alternative DHCP connection that can pave the way for a man-in-the-middle (MITM) attack.

Best Practices for DHCP Deployment

To enable a smooth, effective DHCP deployment, there are a few best practices that you can follow.

Avoid Putting DHCP on Your Domain Controller

Your domain controller should only be responsible for performing core functions, particularly managing your DNS. If you avoid putting DHCP on your domain controller, you can avoid overwhelming it with additional work. 

This enhances network security because it prevents those connecting to your guest Wi-Fi from having access to your domain controller. By preventing this interaction, you keep your attack surface small, especially because you deny a hacker that signs in to your guest Wi-Fi access to your domain controller. If they are able to access this sensitive system, they could hack your DNS.

Use DHCP Failover

Like other kinds of failover, DHCP failover helps ensure you always have a DHCP server to share the essential information needed by hosts in your network. In the event the primary DHCP server goes down, the additional server will provide the DHCP information clients need.

Avoid Using Static IP Addresses When Possible

Deciding between DHCP vs static IP can be a challenging puzzle. What does DHCP stand for? Well, the “dynamic” element of the acronym is important when it comes to maintaining seamless network operations, particularly because it enables the system to change DHCP data as needed. A static IP address is one that does not change. Even though this may seem like a logical decision for devices you feel will always be connected to your network, it can cause problems. 

Suppose, for example, you have to replace that device with an identical but new one. This may require your IT team to manually assign an IP address to the device so it can connect with others in your network, which could take time. Of course, for some devices, such as routers and switches, you need a fixed IP address, primarily because they serve as “connection hubs,” and if their IP address continually changes, the network will not function smoothly. 

Reasons Why Enterprises Must Automate DHCP

It is important for enterprises to automate their DHCP system because it helps eliminate time-consuming manual work that could otherwise consume a lot of your IT team’s energy.

For example, there are a lot of problems, such as printers not connecting with the network or subnets not interfacing with the main network, that can result from DHCP-related issues. By automating your DHCP functions, the system can automatically prevent many of these issues.

Automated DHCP also makes it easier to scale your operations. Instead of having to bring in more people to manually handle what an automated system could manage, you can invest your human resources in other growth-related tasks.

How Can Fortinet Help?

Even though DHCP can ease the burden of network administrators, there is still a lot on their plates, especially when it comes to gaining visibility into what is happening within the organization’s system. By using FortiGate Next-Generation Firewall (NGFW), network admins can gain better visibility into the nature of the traffic entering and exiting the network. Further, because FortiGate inspects individual data packets for threats, administrators can provide all users with a more secure online experience.

FAQs

What is DHCP and why is it used?

Dynamic Host Configuration Protocol (DHCP) is a networking protocol for dynamically assigning IP addresses to each host on your organization's network. DHCP also assigns Domain Name System (DNS) addresses, subnet masks, and default gateways.

What are best practices for DHCP servers?

Some best practices for DHCP servers are to avoid putting DHCP on your domain controller, use DHCP failover, and avoid using static IP addresses when possible.