NetDB: DHCP & BootP

DHCP & BootP - Help

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General
DHCP Flag
Roaming Flag
Default Node DHCP Options
Additional DHCP Options

General

The DHCP (Dynamic Host Configuration Protocol) and BootP (Bootstrap Protocol) pass network configuration information to a host during startup. In NetDB3, DHCP is configured on Node and Network records. For Node records, a unique hardware address must be entered to configure DHCP.

DHCP is also described in Internet RFCs 2131 and 2132. Note that BOOTP is a subset of DHCP commands.

DHCP information is updated from NetDB approximately every 10 minutes.

DHCP Flag (Node Record)

If the DHCP box is checked and a hardware address is entered, the campus DHCP servers will reply to a DHCP request from that hardware address. Default DHCP options will be returned. If specified in the NetDB record, additional DHCP options will also be returned.

Roaming Flag (Node Records)

Roaming DHCP was implemented to allow machines to move to other networks without requiring manual configuration of IP addresses, etc. If the Roaming box is checked, Roaming DHCP is enabled for that hardware address. If the machine now moves to another network that has available roaming DHCP addresses, the DHCP server will give one of these addresses to the mobile machine. For more information about setting up a machine for Roaming DHCP, see DHCP at Stanford.

Default Node DHCP Options

The default Node DHCP options at Stanford University are IP address, subnet mask, gateway, domain name and domain name servers. The option numbers come from RFCs 2131 and 2132.

DHCP Option Option
Number Description

IP Address 50
returns IP address assigned to requesting hardware address

Subnet mask 1 returns 255.255.0.0, in general

Gateway 3
for 171.64 addresses, returns 171.64.1.1; for 171.65 addresses, returns 171.65.1.1

Domain name 15
returns domain name asssigned to the Node

Domain name servers 6
171.64.7.77, 171.64.7.55 and 171.64.7.99 returned in random order

Additional DHCP Options

In NetDB, the following additional DHCP options may be set for Node interfaces, Networks or address spaces. Note: Use with caution as improper use may cause networking problems. For all options except "allow" and "deny", the syntax is <dhcp option> = <value>. For example, "filename = foobar.txt".

DHCP Option Option
Number Node
Interface Net Address
Space Description

filename 67 Y N N bootup file- e.g. xterminals

next-server 66 Y Y Y server holding bootup file

log-servers 7 Y Y Y

domain-name 15 Y Y Y e.g., stanford.edu

domain-name-servers 5 Y Y Y DNS servers

option-144 144 Y N Y for HP printers

allow N Y N

deny N Y N

max-lease-time Y Y Y

default-lease-time 51 Y Y Y DHCP lease time (currently 1 day)

For more information, contact Networking Systems.