DHCP (Dynamic Host Configuration Protocol), is an auto configuration protocol used on IP networks. There are two versions of DHCP, one for IPv4 and one for IPv6
It is suitable for use in high-volume and high-reliability applications. DHCP is available for free download under the terms of the ISC License, a BSD style license.
DHCP uses the same two ports assigned by IANA for BOOTP: UDP port 67 for sending data to the server, and UDP port 68 for data to the client.
DHCP operations fall into four basic phases: IP discovery, IP lease offer, IP request, and IP lease acknowledgement.
With dynamic addressing, a device can have a different IP address every time when it connects to the network. In some systems, the device’s IP address can even change while it is still connected. DHCP also supports a mix of static and dynamic IP addresses.
The base DHCP protocol does not include any mechanism for authentication. Because of this, it is vulnerable to a variety of attacks. These attacks fall into three main categories:
- Unauthorized DHCP servers providing false information to clients.
- Unauthorized clients gaining access to resources.
- Resource exhaustion attacks from malicious DHCP clients.