Heritage Kayaks Heritage Series Dhcp Server Configuration, Informal configuration guide, Subnets

DHCP_LEASE_UPDATE_PERIOD.

118 DHCP Server Operation

dhcpd.leases file to gain information about which leases have been assigned. New leases are appended to the end of the lease file. In order to prevent the file from becoming arbitrarily large, the server periodically creates a new dhcp.leases file from its in-memory lease database, controlled by the values of DHCP_LEASE_UPDATE_THRESHOLD and

If the system crashes in the middle of this process, only the lease file present in flash memory can be restored. This gives a window of vulnerability whereby leases may be lost.

BOOTP support is also provided by this server. Unlike DHCP, the BOOTP protocol does not provide a protocol for recovering dynamically-assigned addresses once they are no longer needed. It is still possible to dynamically assign addresses to BOOTP clients, but some administrative process for reclaiming addresses is required. By default, leases are granted to BOOTP clients in perpetuity, although the network administrator may set an earlier cut-off date or a shorter lease length for BOOTP leases if that makes sense. BOOTP clients may be served in the old way, which is to provide a declaration in the dhcpd.conf file for each BOOTP client, permanently assigning an address to each client.

8.2 DHCP Server Configuration

This section discusses the required format of the dhcpd.conf file, first as an informal guide to the simpler aspects of server configuration, followed by a more detailed reference section.

8.3 Informal configuration guide

This section provides an overview of the DHCP server configuration process.

8.3.1 Subnets

The DHCP server software needs to know the subnet numbers and net masks of all subnets for which it will be providing service. In addition, in order to dynamically allocate addresses, it must be assigned one or more ranges of addresses on each subnet which it can in turn assign to client hosts as they boot. A very simple configuration providing DHCP support might look like this:

subnet 239.252.197.0 netmask 255.255.255.0 { range 239.252.197.10 239.252.197.250;

}