DHCPServer

DHCPServer is a network service implementing the Dynamic Host Configuration Protocol to automate the assignment of IP configuration parameters to devices on an IP network. Its primary role is to provide clients with an IP address, subnet mask, default gateway, and DNS server information, along with other options such as domain name and NTP servers, for a defined lease period.

DHCP servers manage one or more scopes or pools of IP addresses from which leases are issued. They maintain a lease database that records active leases and, optionally, reservations tied to a client's hardware address. When a client connects, DHCP follows a four-step exchange: DHCPDISCOVER, DHCPOFFER, DHCPREQUEST, and DHCPACK. The server can also renew leases with the client via DHCPREQUEST and DHOCPREPLY or DHCPNAK on conflict. In IPv4 the server listens on UDP port 67 and clients on 68; in IPv6, DHCPv6 uses its own message exchange and ports, often in conjunction with router advertisements.

A DHCP server can be configured with options that apply globally or per scope, such as default lease duration, DNS servers, domain name, or vendor-specific parameters. Some networks deploy a DHCP relay agent to forward requests to a centralized server across routers. For redundancy, servers may use failover or load-sharing configurations.

Security considerations include the absence of built-in authentication, which makes DHCP susceptible to rogue servers; mitigations include network segmentation, DHCP snooping, and proper access controls.

Common implementations include ISC DHCP (dhcpd), Kea DHCP, Microsoft DHCP Server, dnsmasq, and others. DHCP servers are widely used in enterprises and campuses to simplify IP management and reduce configuration errors.