IP DHCP Services, DHCP configuration

DHCP. Dynamic Host Configuration Protocol is a network management protocol that is used to dynamically assign the IP address and other information to each host on the network.

The Reverse Address Resolution Protocol (RARP) was defined in RFC 903 in 1984 for the configuration of simple devices, such as diskless workstations, with a suitable IP address. Acting in the data link layer it made implementation difficult in many server platforms. It required that a server be present on each individual network link. RARP was superseded by the Bootstrap Protocol (BOOTP) defined in RFC 951 in September 1985.  DHCP was first defined in RFC 1531 in October 1993, but due to errors in the editorial process was almost immediately reissued as RFC 1541.

DHCP snooping can be configured on LAN switches to exclude rogue DHCP servers and remove malicious or malformed DHCP traffic.

IP dhcp excluded-address

Use This command prevents IP addresses from being assigned by the router’s DHCP server.

Dynamic ARP Inspection (DAI) is a security feature that validates Address Resolution Protocol (ARP) packets in a network. DAI allows a network administrator to intercept, log, and discard ARP packets with invalid MAC address to IP address bindings. This capability protects the network from certain “man-in-the-middle” attacks.