37 lines
2.9 KiB
Markdown
37 lines
2.9 KiB
Markdown
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---
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obj: concept
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wiki: https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol
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rfc: https://datatracker.ietf.org/doc/html/rfc2131
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---
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# Dynamic Host Configuration Protocol
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The Dynamic Host Configuration Protocol (DHCP) is a network management protocol used to automate the assignment of IP addresses and other network configuration parameters to devices on a network. DHCP simplifies the process of configuring devices on a network by providing a centralized mechanism for dynamic IP address allocation.
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## Key Components
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### 1. DHCP Server
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A DHCP server is a network device responsible for assigning IP addresses and other configuration parameters to DHCP clients. It maintains a pool of available IP addresses and leases them to clients on a temporary basis.
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### 2. DHCP Client
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A DHCP client is a device (computer, printer, etc.) that requests network configuration information from a DHCP server. The client typically sends a DHCP discover message to locate available DHCP servers on the network.
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## DHCP Process
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1. **DHCP Discover**: When a device is connected to a network, it broadcasts a DHCP discover message to identify available DHCP servers.
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2. **DHCP Offer**: DHCP servers respond with a DHCP offer message, providing the client with an IP address and other configuration parameters.
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3. **DHCP Request**: The client selects one of the offered IP addresses and sends a DHCP request message to the chosen server.
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4. **DHCP Acknowledge**: The selected DHCP server responds with a DHCP acknowledge message, confirming the allocation of the requested IP address and providing additional configuration details.
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5. **IP Lease Period**: The DHCP server assigns an IP address to the client for a specific lease period. The client must renew its lease before expiration to retain the IP address.
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## DHCP Configuration Parameters
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DHCP servers can provide various configuration parameters, including:
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- **IP Address**: The primary network identifier assigned to the device.
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- **Subnet Mask**: Defines the network's subnetwork structure.
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- **Default Gateway**: Specifies the router that connects the local network to other networks.
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- **Domain Name System ([DNS](DNS.md)) Servers**: Identifies the servers responsible for translating [domain](Domain.md) names into IP addresses.
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- **Domain Name**: Provides the domain name associated with the assigned IP address.
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- **Lease Duration**: The period for which the IP address is allocated to the client.
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## DHCP Security Considerations
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- **Rogue DHCP Servers**: Unauthorized DHCP servers can cause network disruptions. Implementing DHCP snooping can help mitigate this risk.
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- **IP Address Exhaustion**: Regularly monitoring and managing the IP address pool prevents exhaustion and ensures efficient resource utilization.
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- **Man-in-the-Middle Attacks**: Using DHCP secure protocols, such as DHCPv6 Secure Neighbour Discovery (SEND), helps protect against man-in-the-middle attacks.
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