Mar 30, 2023
6 min read
Assigning IP addresses is not an easy task, and a human admin might get confused in the process. This confusion would result in the loss of an internet connection for someone. But the DHCP comes to the rescue in this case.
DHCP (or Dynamic Host Configuration Protocol) is a network management protocol that automatically assigns IP addresses and other communication parameters to devices connected to a network. For example, a router usually acts as a DHCP server in most home networks. It assigns IP addresses to your devices. Implementing this protocol saves time and prevents human errors.
The DHCP (Dynamic Host Configuration Protocol) automatically allocates IP addresses to devices and provides other related configuration information, such as subnet masks and default gateways. If it didn’t exist, the addresses would have to be input manually, which would be inefficient, time-consuming, and error prone.
When a device joins a network, it requests an IP address. The request travels to a DHCP server. A server assigns an address, monitors its usage, and takes it back after the device is shut down. The same IP address can now be reassigned to another device. A device can use this address to communicate with internal and public networks.
Dynamic Host Configuration Protocol servers provide parameters, also known as DHCP options. They describe various factors of IP addresses — for example, how long they can be used. DHCP options usually define:
A default gateway that routes data back and forth between the local network and the internet.
A subnet mask that separates host addresses and network addresses within an IP address.
A DNS server that translates the names of IP addresses into the ones we remember.
DHCP has three methods of IP address allocation:
A functioning DHCP system only needs two components: the server and the client. The DHCP clients are whatever device is connected to the server. The DHCP server allocates IP addresses accordingly to each device.
DHCP servers are incredibly useful in the right environment. However, DHCP servers have some drawbacks that need to be considered before you decide to utilize them fully.
Here are the pros of using DHCP servers:
Here are the cons of using DHCP servers:
A device with a static IP will retain the same IP address. Network admins have to record all static IP addresses to guarantee they aren’t reused. DHCP servers forgo the manual allocation of IP addresses, saving admins a lot of time. Setting up a static IP address is more expensive than leasing a DHCP server.
Most VPN services will use static IP addresses because it’s easier to connect to an online service when an IP address doesn’t change. Static IP addresses are typically reserved for setting up VPN servers, web or home servers, or enabling a user to access a home computer remotely.
The static IP address means routers will always remember that the server is on the network. If the IP address dynamically changes, it adds more work for the network admin. When it comes to allocating IP addresses for a large number of internet of things devices, a DHCP server is the better choice.
When it comes to DHCP servers, lease times refer to how long a device retains an IP address allocated by the server. The default lease time is typically 24 hours. However, you can configure the lease time to be shorter or longer.
Beware of setting a lease time too short, however, as it could cause disruption across the network.
DHCP doesn’t have any authentication, so it is vulnerable to cyberattacks. DHCP can be exploited in the following ways:
All these issues can result in DDoS and man-in-the-middle attacks. However, admins can reduce the risk by using the relay agent information option and tagging DHCP messages when they arrive. They can also use network access control to protect DHCP.
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