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 including:
1. 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.
2. 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.
3. 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.
‘Learn More about Static vs Dynamic IP’
