DHCP utilizes UDP ports 67 and 68 for communication.
Understanding DHCP Ports
The Dynamic Host Configuration Protocol (DHCP) is essential for network management, automatically assigning IP addresses and other network configuration parameters to devices. To understand its operation, it's crucial to know which ports DHCP uses. DHCP communication involves two primary ports:
- Server Port: UDP port 67
- Client Port: UDP port 68
DHCP Communication Flow
- DHCP Discover: When a new device connects to the network and needs an IP address, it sends a DHCP Discover message to UDP port 67.
- DHCP Offer: The DHCP server listens on UDP port 67. Upon receiving the Discover message, it responds with a DHCP Offer message using port 67.
- DHCP Request: The client sends a DHCP Request message back to the server using port 68 to accept the offer of an IP address.
- DHCP ACK: The server completes the process by sending a DHCP Acknowledgement (ACK) message back to the client using port 67, confirming the IP address allocation.
Practical Insights
- Troubleshooting: Knowing these ports is useful for network troubleshooting, particularly if a DHCP server or clients are not functioning as expected.
- Firewall Rules: If a firewall is in place, ensure UDP ports 67 and 68 are open to allow DHCP communication.
Summary of DHCP Ports
| Port Number | Protocol | Direction | Purpose |
|---|---|---|---|
| 67 | UDP | Server | DHCP server listening and sends responses |
| 68 | UDP | Client | DHCP client listening and sends requests |
The information provided is sourced from the reference: DHCP uses UDP port 67 on the server side and UDP port 68 on the client side.11-Oct-2023.
