The Dynamic Host Configuration Protocol automatically assigns IP addresses to computer systems on a network.
You can find information on DHCP (the Dynamic Host Configuration Protocol) here. Feel free to check out one of the links to get started: there are several sample configurations available for isc’s dhcpd, isc’s dhclient and the dhcpcd client.
DHCP is the Dynamic Host Configuration Protocol as defined in RFC2131 at the IETF.
For IPv6 networks DHCP is no longer needed; instead the ICMPv6 protocol is used. Clients ask the network for configuration information and IPv6 routers will answer with a Router Advertisement packet that contains the appropriate settings. Consequently, you should normally never block ICMP traffic on IPv6 networks.