ISC Dynamic Host Configuration Server (dhcpd)

Linux IPv6 HOWTO (en)
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# 22.6. ISC Dynamic Host Configuration Server (dhcpd)

ISC DHCP supports IPv6 since version 4.x.

## 22.6.1. Configuration of the ISC DHCP server for IPv6 (dhcpd)

Note that currently, the ISC DHCP server can only serve IPv4 or IPv6, means you have to start the daemon twice (for IPv6 with option “-6”) to support both protocols.

### 22.6.1.1. Simple configuration

Create a dedicated configuration file /etc/dhcp/dhcpd6.conf for the IPv6 part of the dhcpd. Note, that the router requires to have a interface configured with an IPv6 address out of the defined subnet.

    default-lease-time 600;
    max-lease-time 7200;
    log-facility local7;
    subnet6 2001:db8:0:1::/64 {
            # Range for clients
            range6 2001:db8:0:1::129 2001:db8:0:1::254;
            # Additional options
            option dhcp6.name-servers fec0:0:0:1::1;
            option dhcp6.domain-search "domain.example";
            # Prefix range for delegation to sub-routers
            prefix6 2001:db8:0:100:: 2001:db8:0:f00:: /56;
            # Example for a fixed host address
            host specialclient {
        		host-identifier option dhcp6.client-id 00:01:00:01:4a:1f:ba:e3:60:b9:1f:01:23:45;
            	fixed-address6 2001:db8:0:1::127;
        	}
    }

Note that the “dhcp.client-id” no longer belongs to a MAC address, an unique ID is used instead! “dhcp6c” (see above) uses the file /var/lib/dhcpv6/dhcp6c_duid (would be created during first start, if not existing) as unique identity. It's a 14 byte long identifier, starting with a 2 byte length information (usually “0x000e”):

    # hexdump -e '"%07.7_ax " 1/2 "%04x" " " 14/1 "%02x:" "\n"' /var/lib/dhcpv6/dhcp6c_duid 0000000 000e 00:01:00:01:4a:1f:ba:e3:60:b9:1f:01:23:45:

## 22.6.2. Usage

### 22.6.2.1. dhcpd

Start server in foreground:

    # /usr/sbin/dhcpd -6 -f -cf /etc/dhcp/dhcpd.conf eth1
    Internet Systems Consortium DHCP Server 4.1.0
    Copyright 2004-2008 Internet Systems Consortium.
    All rights reserved.
    For info, please visit http://www.isc.org/sw/dhcp/
    Not searching LDAP since ldap-server, ldap-port and ldap-base-dn were not specified in the config file
    Wrote 0 leases to leases file.
    Bound to *:547
    Listening on Socket/5/eth1/2001:db8:0:1::/64
    Sending on   Socket/5/eth1/2001:db8:0:1::/64

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