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(also Dynamic Host Configuration Protocol)

DHCP definition

DHCP 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.

See also: PPPoE

How DHCP works

  1. Discovery: A device connects to a network and sends broadcast messages to discover DHCP servers.
  2. Offer: A DHCP server responds by delivering an IP address to the device.
  3. Request: The device acknowledges the information and asks permission to use the assigned IP address.
  4. Acknowledgment: The server sends a final message to the requesting device. It contains all the other configuration information needed to access the network, such as the gateway and DNS servers.

The DHCP server then monitors the IP address being used and can take it back when the device disconnects. This allows assigning the same IP address to other devices as needed.

DHCP advantages

  • IP address conflict resolution. Automatically assigns unique IP addresses to each device on the network. This minimizes conflicts caused by assigning one IP address to several devices at the same time.
  • Easier network management. Eliminates the need for administrators to manually assign IP addresses to each device on the network.
  • Improved mobility support. Allows mobile devices to move between networks without IP address reconfiguration. This makes it easier for users to connect to different networks and access resources while on the go.
  • More flexibility. Gives flexible configuration options, such as assigning different IP addresses to different devices or groups of devices on the network.

DHCP security issues

  • DHCP doesn’t require authentication, making a DHCP server a weak link in the security chain.
  • Malicious actors can exhaust DHCP resources with a DDoS attack and make it crash.
  • Rogue DHCP servers can be used for man-in-the-middle attacks.

Further reading

Ultimate digital security