The server version of DHCP fully supports the following BOOTP parameters. If a BOOTP client makes a request of the server, it acts as a BOOTP server.

Boot File

Specifies the fully qualified path name of the client's default boot image.

Boot File Server Address

Specifies the server address of the boot file.

Boot File Server Name

Specifies the host name of the server with the boot file.

Boot File Size

Specifies the length in 512-octet blocks of the default boot image for the client. Specify the file length as a number.

Cookie Servers

Specifies a list of RFC 865 cookie servers available to the client. Enter the servers in order of preference.

Use this format: ddd.ddd.ddd.ddd.

DNS Domain Name

Specifies the domain name the client should use when resolving host names through the Domain Name System.

DNS Servers

Specifies a list of DNS (STD 13, RFC 1035) name servers available to the client. Enter the servers in order of preference.

Use this format: ddd.ddd.ddd.ddd.

Extensions Path

Specifies a string which identifies a file, retrievable through TFTP, that contains information that the server can interpret in the same way as the 64-octet vendor-extension field in the BOOTP response. There is no limit on the length of this file.

Home Directory

Specifies the directory where the boot file resides, if it is not specified in the boot file name.

Also specifies the name of the client. The name can or can not be qualified with the local domain name. See RFC 1035 for character-set restrictions.

Host IP Address (BOOTP only)

Specifies the host IP address for BOOTP clients.

Host Name

Specifies the host name parameter if you are setting up a configuration for a single client identified by its MAC address.

Also specifies the name of the client. The local domain name can or can not qualify the client name. See RFC 1035 for character-set restrictions.

IEN-116 Name Servers

Specifies a list of IEN-116 name servers available to the client. Enter the servers in order of preference.

Use this format: ddd.ddd.ddd.ddd.

Impress Servers

Specifies a list of Imagen Impress servers available to the client. Enter the servers in order of preference.

Use this format: ddd.ddd.ddd.ddd.

Log Servers

Specifies a list of MIT-LCS UDP log servers available to the client. Enter the servers in order of preference.

Use this format: ddd.ddd.ddd.ddd.

LPR Servers

Specifies a list of RFC 1179 line-printer servers available to the client. Enter the servers in order of preference.

Use this format: ddd.ddd.ddd.ddd.

Merit Dump File

Specifies the path name of a file to which the client's core image should be dumped in the event the client fails. The path is formatted as a character string consisting of characters from the NVT ASCII character set.

Resource Location Servers

Specifies a list of RFC 887 resource location servers available to the client. Enter the servers in order of preference.

Use this format: ddd.ddd.ddd.ddd.

Root Path

Specifies the path name that contains the client's root directory or partition. The path is formatted as a character string consisting of characters from the NVT ASCII character set.

Routers

Specifies the list of IP addresses for routers (gateways) on the client's subnet. If you specify a default gateway of 0.0.0.0, the server uses the client's IP address as the default gateway address.

Use this format: ddd.ddd.ddd.ddd.

Subnet Mask

Specifies the client's subnet mask as described in RFC 950.

A subnet mask allows the addition of subnetwork numbers to an address, and provides for more complex address assignments.

If you specify both the subnet mask and the router option in a DHCP reply, the subnet mask option must be first.

Use this format: ddd.ddd.ddd.ddd.

Send Client's Host Name

Specifies whether the server should send the client's host name to the client in the reply.

The following are valid values:

False:	Do not send the client's host name. Default.
True:	Send the client's host name.

Swap Server

Specifies the IP address of the client's swap server.

Use this format: ddd.ddd.ddd.ddd.

TFTP Root Directory

Specifies the root directory for Trivial File Transfer Protocol (TFTP).

Time Offset

Specifies the offset of the client in seconds from Universal Coordinated Time (UTC).

Time Servers

Specifies a list of RFC 868 time servers available to the client. Enter the servers in order of preference.

Use this format: ddd.ddd.ddd.ddd.

Vendor Magic Cookie

Specifies a vendor magic cookie for the client.

IP layer parameters affect the operation of the IP layer on a per-host basis.

Broadcast Address

Specifies the broadcast address in use on the client's subnet.

Forward Nonlocal Datagrams

Specifies whether the client should configure its IP layer to allow forwarding of datagrams with nonlocal source routes.

The following are valid values:

False:	Disable forwarding of datagrams with nonlocal source routes.
True:	Enable forwarding.

IP Forwarding

Specifies whether the client should configure its IP layer for packet forwarding.

The following are valid values:

False:	Disable IP forwarding.
True:	Enable IP forwarding.

IP Time-to-Live

Specifies the default time-to-live that the client should use on outgoing datagrams. Specify time-to-live as an octet.

Minimum value	1
Maximum value	255

Interface MTU

Specifies the maximum transmit unit (MTU) to use on this interface. Specify the MTU as a 16-bit unsigned integer.

Minimum legal value is 68.

Maximum Reassembly Size

Specifies the maximum size datagram that the client should be prepared to reassemble. Specify the size as a 16-bit unsigned integer.

Minimum legal value is 576.

MTU Plateaus

Specifies a table of MTU sizes to use when performing Path MTU Discovery as defined in RFC 1191. The table is formatted as a list of 16-bit unsigned integers, ordered from smallest to largest.

The minimum value cannot be smaller than 68.

PMTU Timeout

Specifies the timeout to use when aging Path MTU values discovered by the mechanism defined in RFC 1191. Specify the timeout in seconds as a 32-bit unsigned integer.

Perform Mask Discovery

Specifies whether the client should perform subnet mask discovery using the Internet Control Message Protocol (ICMP).

The following are valid values:

False:	Client should not perform mask discovery.
True:	Client should perform mask discovery.

Perform Router Discovery

Specifies whether the client should solicit routers using the Router Discovery mechanism defined in RFC 1256.

The following are valid values:

False:	Client should not perform router discovery.
True:	Client should perform router discovery.

Policy Filters

Specifies policy filters for nonlocal source routing. The filters consist of a list of IP addresses and masks that specify destination/mask pairs with which to filter incoming source routes.

The client should discard a source-routed datagram whose next-hop address does not match one of the filters.

Use this format: ddd.ddd.ddd.ddd.

Solicit Router

Specifies the IP address to which the client should transmit router solicitation requests.

Use this format: ddd.ddd.ddd.ddd.

Static Routes

Specifies a list of static routes that should be installed in the client's routing table. If you specify multiple routes to the same destination, list them in descending order of priority.

The routes consist of a list of IP address pairs. The first address is the destination address, and the second address is the router for the destination.

Note The default route (0.0.0.0) is an illegal destination for a static route.

Use this format: ddd.ddd.ddd.ddd.

Subnets Are Local

Specifies whether the client can assume that all subnets of the IP network to which the client is connected use the same MTU (maximum transmit unit) as the subnet of the network to which the client is directly connected.

The following are valid values:

False:	The client should assume that some subnets of the directly connected network can have smaller MTUs.
True:	All subnets share the same MTU.

Supply Masks

Specifies whether the client should respond to subnet mask requests using the Internet Control Message Protocol (ICMP).

The following are valid values:

False:	Client should not respond.
True:	Client should respond.

Lease parameters allow you to change information about the IP lease times. Lease times determine the length of time a client can use an IP address.

DHCP Rebinding Time

Specifies the time interval in seconds from address assignment until the client requests a new lease from any server on the network.

DHCP Renewal Time

Specifies the time interval in seconds from address assignment until the client attempts to extend the duration of its lease with the original server.

DHCP Lease Time

The client uses this option in a client request (DHCPDISCOVER or DHCPREQUEST) message to request a lease time for the IP address.

The server uses this option in a server reply (DHCPOFFER) message to specify the lease time it is willing to offer.

Enter the time in months, days, hours, minutes, and seconds; for example, 2 months 5 days 45 minutes. By default, the server interprets the lease in seconds. For an infinite lease for a BOOTP client, specify a -1.

Link Layer parameters affect the operation of the Link layer on a per-host basis.

ARP Cache Timeout

Specifies the timeout in seconds for ARP cache entries. The time is specified as a 32-bit unsigned integer.

Ethernet Encapsulation

If it is an Ethernet interface, use this option to specify whether the client should use Ethernet Version 2 (RFC 894) or IEEE 802.3 (RFC 1042) encapsulation.

The following are valid values:

False:	Use RFC 894 encapsulation.
True:	Use RFC 1042 encapsulation.

Trailer Encapsulation

Specifies whether the client should negotiate the use of trailers (RFC 893) when using the ARP protocol.

The following are valid values:

False:	Client should not attempt to use trailers.
True:	Client should attempt to use trailers.

NetBIOS parameters configure NetBIOS related parameters on a per-host basis.

NetBIOS Datagram Distribution Server

Specifies a list of RFC 1001/1002 NBDD servers listed in the order of preference.

Use this format: ddd.ddd.ddd.ddd.

NetBIOS Name Server/WINS Server

Specifies a list of RFC 1001/1002 NBNS name servers listed in the order of preference.

Use this format: ddd.ddd.ddd.ddd.

NetBIOS Node Type

Allows you to configure NetBIOS-over-TCP/IP clients as described in RFC 1001/1002. Specify the value as a single octet (from 0 to 255) that identifies the client type as shown in Table 7-7.

Table 7-7 NetBIOS Node Type and Value

Node Type	Value (hexadecimal)
B-node	1
P-node	2
M-node	4
H-node	8

Note The NetBIOS over TCP/IP clients must be configurable.

NetBIOS Scope

The NetBIOS scope option specifies the NetBIOS scope text parameter for the client as specified in RFC 1001/1002. There can be character-set restrictions.

Network parameters allow you to change basic network configuration information.

Finger Servers

Specifies a list of finger servers available to the client. List the servers in the order of preference.

IRC Servers

Specifies a list of IRC (Internet Relay Chat) servers available to the client. List the servers in the order of preference.

Mobile IP Home Agents

Specifies a list of IP addresses indicating mobile IP home agents available to the client. List the agents in the order of preference.

NNTP Servers

Specifies a list of Network News Transfer Protocol (NNTP) servers available to the client. List the servers in the order of preference.

NetWare Domain

Specifies the NetWare domain name.

NetWare Options

Specifies a list of NetWare servers.

POP3 Servers

Specifies a list of Post Office Protocol 3 (POP3) servers available to the client. List the servers in the order of preference.

SMTP Servers

Specifies a list of Simple Mail Transfer Protocol (SMTP) servers available to the client. List the servers in the order of preference.

STDA Servers

Specifies a list of StreetTalk Directory Assistance (STDA) servers available to the client. List the servers in the order of preference.

StreetTalk Servers

Specifies a list of StreetTalk servers available to the client. List the servers in the order of preference.

WWW Servers

Specifies a list of World Wide Web servers available to the client. List the servers in the order of preference.

TCP parameters affect the operation of the TCP layer on a per-host basis.

Keep Alive Interval

Specifies the interval that the client should wait before sending a keepalive message on a TCP connection.

A value of 0 (zero) indicates that the client should not generate keepalive messages on connections unless an application requests them.

Specify the time in seconds as a 32-bit unsigned integer.

Keep Alive Octet

This parameter specifies whether the client is to send TCP keepalive messages with a garbage octet for compatibility with older implementations.

The following are valid values:

False:	Do not send a garbage octet.
True:	Send a garbage octet. (Sets the compatibility mode.)

TCP Default Time-to-Live

This option specifies the default time-to-live that the client uses when sending TCP segments.

Minimum value is 1.

Time parameters allow you to change information about network time services available to clients on the network.

Network Time Protocol (NTP) Servers

Specifies a list of RFC 1305 time servers available to the client. List the server addresses in the order of preference.

Use this format: ddd.ddd.ddd.ddd.

X parameters configure X11-related parameters on a per-host basis.

X Window Display Manager

Specifies a list of IP addresses of systems that are running the X Window System display manager and that are available to the client.

Enter IP addresses in the order of preference.

Use this format: ddd.ddd.ddd.ddd.

X Window Font Server

Specifies a list of X Window System font servers available to the client. Enter the server addresses in the order of preference.

Use this format: ddd.ddd.ddd.ddd.

After you convert your existing BOOTP file to the new DHCPCAP. file as described in Section 7.4.1, you are ready to begin serving your existing BOOTP clients without any further changes.

This section explains how to use the GUI to configure static IP addressing for any DHCP/BOOTP clients you add in the future, as appropriate.

Configuring static IP addressing for DHCP and BOOTP client requires different steps described in the following sections.

7.6.1 Static IP Addressing for BOOTP Clients

To define static IP addressing, specify a specific IP address for a specific MAC address as follows:

1. Start the GUI by entering the following command:

   $ DHCPGUI

2. Click the Nodes tab.
3. Choose [New Record].
4. Enter the host name (Name).
5. Enter the MAC/hardware address. For example, 08:00:20:3f:12:4b.
6. Choose Hardware Type from Key Parameters. Enter the type of network on which the node resides. Enter the hardware type using the symbol or the type number as shown in Table 7-6.
7. Choose [Host IP Address].
8. Enter the Host IP address of the host computer for this node.
9. As appropriate, enter information for Network, Lease, Time, BOOTP, NetBIOS, X Window, TCP, IP, and Link parameters. For more information about these parameters, refer to Section 7.5.3.4.
10. Choose Update from the File menu to update the server with the new configuration.

Select static addressing if you want to assign a specific IP address with a permanent lease time to a DHCP client, and you do not want the client to be able to release this IP address. Also, select static addressing if you need to select an IP address that is not part of any IP address pool.

Selecting an IP address from outside an IP address pool allows the server to specify a permanent mapping between a DHCP client's MAC address and the desired IP address. A client can reuse and release any address within an IP pool.

To configure a specific, permanent address for a DHCP client, do the following:

1. Start the GUI by entering the following command:

   $ DHCPGUI

2. Click the Server/Security tab.
3. Choose Active IP Snapshot, then choose [New Record].
4. Enter the MAC address.
5. Enter the MAC type.
6. Enter the MAC address length.
7. Enter an IP address that does not belong to any IP address pools.
8. Enter -1 (infinite lease) for the lease expiration.
9. Enter the server IP address.
10. If you want a name associated with the client, specify the client's host name and domain name.

If you set the Use MAC addr as Client ID parameter to True, the server uses the MAC address to uniquely identify the clients. The MAC address field might not be the actual MAC address of the client's network adapter. Clients that modify the structure of the MAC address before sending it to the server include:

• Windows 95, Windows NT, and Windows for Workgroups 3.11 with Microsoft TCP/IP
  On these platforms, the MAC address is prefixed with the hardware type. The MAC type is 0 and the length is 7 (instead of 6). For example, if your Ethernet address is 11:22:33:44:55:66, you need to specify the following for the static IP mapping:
  • MAC Address: 01:11:22:33:44:55:66
  • MAC Type: 0
  • MAC length: 7
• FTP Software's OnNet client
  On this platform, the string "cid-" prefixes the MAC address. The MAC type is 0 and the length is 16. For example, if your Ethernet address is 11:22:33:44:55:66, you need to specify the following for the static IP mapping:
  • MAC Address: cid-112233445566
  • MAC Type: 0
  • MAC length: 16

After you run the TCPIP$CONFIG.COM procedure and enable the DHCP server on your system, you can manually define the following client information on a case-by-case basis:

• Static, dynamic, or finite addressing
• Other identifying parameters, such as default gateways and DNS domain names

Defining client addressing and additional parameters manually involves the following steps:

1. Modify the appropriate text-based configuration files.
   These files are listed in Section 7.2.2.
   You manually edit the DHCP configuration files using a text editor such as EDT, TPU, or LSE. Depending on your environment, you may or may not need to modify all the files.
2. If appropriate, run DHCP utilities to update the binary databases.
   When you are modifying information already stored in the databases, you use command line utilities to access and update the database contents. These utilities are defined as both OpenVMS and UNIX commands. Table 7-10 lists the utilities.
3. Reinitialize the DHCP server for the changes to take effect (see Section 7.7.3).

The DHCPCAP. file describes the various configuration parameters for the clients. This file is similar to the standard bootptab file used by most BOOTP servers. Each entry in the file can describe a single machine (per-node basis) or all the machines within a subnet (per-subnet basis) or a group of machines (per-group basis).