By : Santosh Yadav IIT Kanpur IPv6 DHCP By : Santosh Yadav IIT Kanpur

IPv6 Dynamic Host Configuration Protocol Overview Evolution Of DHCPv6 DHCPv6 Concepts Installation Configuration

Evolution Of DHCPv6 To boot the machines in a LAN, needs lot of network parameters to be configured in each machine. In order to avoid this manual process, all the network parameters are put in a server and when a machine in LAN is booting, it will contact the server for the configuration parameters. This is called BOOTP server. Later it is extended to DHCP with additional features. Generally called DHCP

Evolution Of DHCPv6 IP configuration in IPV6 is carried out by IPV6 auto-configuration IPv6 auto-configuration Stateless nodes configure addresses themselves with information from routers (if available); no managed addresses Stateful nodes use DHCPv6 to obtain addresses. Duplicate address detection (DAD) used to avoid duplicated addresses

What is DHCPv6 ? The Dynamic Host Configuration Protocol for IPv6 Dhcpv6 Concepts What is DHCPv6 ? The Dynamic Host Configuration Protocol for IPv6 (DHCP) enables DHCP servers to pass configuration parameters such as IPv6 network addresses to IPv6 nodes. DHCPv6 protocol Released in RFC 3315 This protocol is a stateful counterpart to "IPv6 Stateless Address Autoconfiguration" (RFC 2462). Used separately or concurrently with the latter to obtain configuration parameters.

The following lists the main differences between DHCPv4 and DHCPv6: Dhcpv6 Concepts… DHCPv6 Versus DHCPv4 The following lists the main differences between DHCPv4 and DHCPv6: Unlike DHCPv4, IPv6 address allocation in DHCPv6 is handled using a message option. The message types, such as DHCPDISCOVER and DHCPOFFER supported by DHCPv4 are removed in DHCPv6. Instead, DHCPv6 servers are located by a client SOLICIT message followed by a server ADVERTISE message Unlike DHCPv4 clients, DHCPv6 clients can request multiple IPv6 addresses.

A method of providing stateful IPv6 address configuration/assignment Dhcpv6 Concepts… Why we need dhcpv6 ? A method of providing stateful IPv6 address configuration/assignment Also provides “other” network information DNS servers NIS information DHCP allows centralized control and auditing of IP address assignments Central point of control for resources Dynamic DNS updates More security versus stateless

Msg-type Transaction-id Options (variable) Dhcpv6 Concepts… DHCPv6 Basic Message Format 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 Msg-type Transaction-id Options (variable) • SOLICIT • ADVERTISE • REQUEST • CONFIRM • RENEW • REBIND • REPLY • RELEASE • DECLINE • RECONFIGURE • INFORMATION-REQUEST • RELAY-FORW • RELAY-REPL

Message Type Option Meaning REBIND (6) SOLICIT(1) A client sends a Solicit message to locate servers. ADVERTISE (2) A server sends an Advertise message to indicate that it is available for DHCP service, in response to a Solicit message received from a client. REQUEST (3) A client sends a Request message to request configuration parameters, including IP addresses, from a specific server. REPLY (4) A server sends a Reply message containing assigned addresses and configuration parameters in response to a Solicit, Request, Renew, Rebind message received from a Client. RENEW (5) A client sends a Renew message to the server that originally provided the client's addresses and configuration parameters to extend the lifetimes on the addresses assigned to the client. REBIND (6) A client sends a Rebind message to any available server to extend the lifetimes on the addresses assigned to the client.

Messages exchanged using UDP Dhcpv6 Concepts… DHCP Messages Messages exchanged using UDP Client port – udp/546 Server Port – udp/547 Client uses Link-Local address or addresses determined using other methods to transmit and receive DHCP messages. Server receives messages from clients using a reserved, Link-Scoped multicast address.

All_DHCP_Relay_Agents_and_Servers Dhcpv6 Concepts… DHCP Multicast Addresses All_DHCP_Relay_Agents_and_Servers Link-scoped multicast address used by a client to communicate with on-link relay agents and servers FF02::1:2 All_DHCP_Servers Site-scoped multicast address used by a relay agent to communicate with servers FF05::1:3

Options data(option –len octets) Dhcpv6 Concepts… DHCPv6 option format and base option 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 Option-code Option length Options data(option –len octets) • Client Identifier • Server Identifier • Identity Association for Non-temporary Addresses • Identity Association for Temporary • IA Address • Option Request • Preference • Elapsed Time • Relay Message • Authentication • Server Unicast • Status Code • Rapid Commit • User Class • Vendor Class • Vendor-specific Information • Interface-Id • Reconfigure Message • Reconfigure Accept

Dhcpv6 Concepts… DHCP Unique Identifer (DUID) Each DHCP client and server has a DUID. DHCP servers use DUIDs to identify clients for the selection of configuration parameters and in client Identity Associations. Unique across all clients and servers Should not change over time (if possible) Must be < 128 octets long

Client must associate at least one distinct IA with each Dhcpv6 Concepts… Identity Association An identity association (IA) is a construct through which a server and client can identify, group, and manage a set of related IP addresses. Client must associate at least one distinct IA with each network interface requesting assignment of IP addresses from DHCP server (IAID) Must be associated with exactly one interface Must be consistent across restarts by the client

DHCPv6 working DHCP client DHCP server B DHCP server A T I M E SOLICIT ADVERTISE ADVERTISE REQUEST Client select one advertise server B REPLY Client Now use address and parameter for lifetime Client renew life time RENEW REPLY Client releases address when shutting down RELEASE

Dhcpv6 Concepts… Dhcpv6 operation : Client sends messages to link-local multicast address Server unicasts response to client Information-Request / Reply - provide client configuration information but no addresses Confirm / Reply - assist in determining whether client moved Reconfigure - allow servers to initiate a client reconfiguration Basic client/server authentication capabilities in base standard. DHCP Unique Identifier (DUID) used to identify clients & servers Identity Association ID (IAID) used to identify a collection of addresses Relay Agents used when server not on-link Relay Agents may be chained

Ongoing Project Previously DHCPv6 v1.001and now DHCPv6 2.001 available for the HP-UX 11i v1 and HP-UX 11i v2 operating systems http:/docs.hp.com Dibbler is a portable DHCPv6 implementation on Linux 2.4/2.6 and Windows XP and Windows 2003. This project was started as master thesis by Tomasz Mrugalski and Marek Senderski of Computer Science faculty on Gdansk University of Technology. http://klub.com.pl/dhcpv6/ Project UNIX name: dhcpv6 Operating System: All POSIX (Linux/BSD/UNIX-like OSes), Linux http://dhcpv6.sourceforge.net/

Update with dhcpv6-0.10-11_FC3.i386.rpm using Installation Dhcpv6 server : Update with dhcpv6-0.10-11_FC3.i386.rpm using # rpm -U dhcpv6-0.10-11_FC3.i386.rpm Create a database directory #mkdir /var/db/dhcpv6 Copy sample server configuration file # cp dhcp6s.conf /etc/dhcp6s.conf Start the server daemon using # dhcp6s –dDf eth0

Update with dhcpv6_client-0.10-11_FC3.i386.rpm using Installation… Dhcpv6 client : Update with dhcpv6_client-0.10-11_FC3.i386.rpm using # rpm -U dhcpv6_client-0.10-11_FC3.i386.rpm Copy sample client configuration file # cp dhcp6c.conf /etc/dhcp6c.conf Start the client daemon using # dhcp6c –dDf eth0

In Fedora core 3 following files are configured : Configuration In Fedora core 3 following files are configured : Server configuration : /etc/sysconfig/dhcp6s /etc/dhcp6s.conf File : /etc/sysconfig/dhcp6s Specify the interface for dhcp6s DHCP6SIF=eth0

Server configuration... File : /etc/dhcp6s.conf Configuration… interface eth0 { server-preference 255; renew-time 60; rebind-time 90; prefer-life-time 130; valid-life-time 200; allow rapid-commit; link BBB { pool{ range 2001:0E30:1402:2::4 to 2001:0E30:1402:2::ffff/64; prefix 2001:0E30:1402::/48; };

In Fedora core 3 following files are configured : Configuration… In Fedora core 3 following files are configured : Client configuration : /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/dhcp6c.conf File : /etc/sysconfig/network-scripts/ifcfg-eth0 IPV6INIT=yes DHCP6C=yes

client configuration... Configuration… interface eth0 { File : /etc/dhcp6c.conf interface eth0 { #information-only; send rapid-commit; #request prefix-delegation; #request temp-address; address { 2001:0E30:1402:1:9656:3:4:56/64; };

Testing Start the server daemon in debug mode in foreground #dhcp6s –dDf eth0 Restart the network service of client #service network restart See the address assignment #ifconfig

Thank you for your attention Any Question?