HP OpenVMS Systems Documentation

The default setting is 8.

Ignore Hardware Type

Set this option to True only to work around problems introduced by clients that broadcast multiple DHCP requests with conflicting hardware types (for example, HP Jet Direct). The default value is False.

Ignore Name Owner

Listen on PPP Interfaces

If True, the server will respond to DHCP requests on Point-to-Point Protocol (PPP) interfaces of the host. By default, DHCP ignores these interfaces.

Min BOOTP Packet Size

The default minimum packet size is 300 bytes.

Name Service

DNS is the only name service available with TCP/IP Services.

Name Service Updatable

Ping BOOTP Clients

• If the address was from the dynamic pool, the server marks it as unavailable, and selects a new address from the pool.
• If the address was statically configured, the server refuses to configure the client.

The following are valid values:

Ping Timeout

If you do not want the server to ping before giving out an IP address, set the timeout value to 0.

The default is 500 milliseconds.

Provisional Time To Live

The default is 1 minute.

Reply to Relay On Local Net

The following are valid values:

Restrict to Known MAC Addresses

Choose True to have the server provide DHCP information to only those hosts that have a known MAC address. To register a known MAC address client, use Preload MAC Addresses feature from the Server/Security tab or use the DBREG utility.

The following are valid values:

Send Options in DHCP Offer

The following are valid values:

Support Microsoft RAS Server

The following are valid values:

Use MAC addr as client ID

The following are valid values:

Use the IP Ranges parameters to specify the IP addresses that are available to assign to clients.

To configure the server IP ranges:

1. Click the Server/Security tab.
2. Choose IP Ranges from the drop-down list.
3. Choose [New IP Range].
4. For each IP range, enter the subnet address or name, a server address, and an IP range to be assigned to clients on the selected subnets.

IP Range Parameters

You can change any or all of the IP range parameters described in this section.

Subnet Address

Enter the subnet address or name.

DHCP Server (address)

Enter the IP address or the name of the Server. For cluster failover configurations, enter 0.0.0.0 for the IP address.

IP Ranges

The IP Address Range is a group of unique IP addresses that the server can assign to clients on a selected subnet. To assign an IP Address Range to a subnet:

1. Enter the beginning of the IP Address Range for the subnet: network, subnet, and host address.
2. Enter the end of the IP Address Range.
3. If your network has more than one subnet, enter the remaining subnet IP numbers.

Note A subnet address can have more than one corresponding IP Address Range.

The server can configure clients on more than one subnet when the routers between the server and the client forward BOOTP packets.

Use the Host Names Lists Parameters to configure a host name. If you have set the server configuration so that the server automatically accepts the name a client suggests for itself or you have added A and PTR records for the hosts to your DNS/BIND database, you do not need to set up host names.

To configure a host name:

1. Click the Server/Security tab.
2. Choose Host Name Lists from the drop-down list.
3. Choose [New Host name List].
4. For each host name, enter:
   • Domain name
   • DHCP server name
   • Host name Prefix (required as part of the host name)
   • Host names

You can use the following host name list parameters to set up host names.

Domain Name

Specifies the domain name. Enter the domain name exactly as it was assigned by the NIC Domain Registrar, including its top-level domain extension. For example, enter school.edu , company.com , or city.gov .

DHCP Server

Enter the IP address or name of the DHCP server.

Hostname Prefix

Specifies a host name prefix.

The host name prefix is used when a computer requests a host name and one is not available.

Using the mycompany.com domain as an example, assume:

• All names in the host name list have been assigned.
• Host name prefix is magic.

Then, the DHCP server gives the host names magic1 and magic2 to the next two computers that request host names.

Enter a specific host name prefix.

Host names

Specifies the list of host names. Enter as many host names as needed. Different DHCP servers can own the same host names.

You can use the Active IP Snapshot window to view the lease database, manually add a new lease, and remove a lease.

Viewing a Lease

The left side of the Active IP Snapshot window lists each DHCP client with a lease granted by the server. To see the details:

1. Click the Server/Security tab.
2. Choose Active IP Snapshot from the drop-down list.
3. Select a record on the left side of the window.
4. Review the information on the right side of the window. It lists the information that applies to the selected record.

Adding a New Lease

Typically you only add a new lease when you intend to permanently attach a hardware address to an IP address. The IP address does not need to come from the DHCP IP addresses you have defined.

To add a new lease, use the following procedure:

1. Click the Server/Security tab.
2. Choose Active IP Snapshot from the drop-down list.
3. Choose [New Record].
4. Enter a value for each parameter.
5. Click Add.

Changes made to the database take effect immediately.

Note Ensure that the IP address you specify does not belong to any pool of IP addresses configured in an IP range. If it does, it could be released and used by other clients (MAC address). If you want to grant a lease for an infinite period of time, which effectively make a permanent binding between an IP address and a MAC address, set the Lease Expiration parameter to a value of -1.

Removing a Lease

To remove a lease, use the following procedure:

1. Click the Server/Security tab.
2. Choose Active IP Snapshot from the drop-down list.
3. On the left side of the window, select the record you want to remove.
4. Click Delete.

Changes to the database take effect immediately.

Refreshing the Active IP Snapshot Window

To refresh the Active IP Snapshot window so that it reflects the current status of the database, click Refresh. This parameter will refresh data on leases that are active or expired, or both.

Use the Preload MAC Addresses window to restrict the assignment of IP addresses. To enable this security measure, set the Restrict to known MAC addr value to True in the Server/Security Parameters window. You can then manually assign the desired MAC addresses. The server ignores all other client DHCP requests.

Checking the Status of a MAC Address

Each configured MAC address and type is listed on the left side of the Preload MAC Addresses window. To see the details of a MAC address:

1. Click the Server/Security tab.
2. Choose Preload MAC Addresses from the drop-down list.
3. Select a record from the left side of the window.

The right side of the window lists the information applicable to the address.

Adding a New MAC Address

Initially, you may need to add large numbers of MAC addresses to the known clients database; it may be more practical to use the command line utility jdbreg for this purpose. You would typically use the GUI to add MAC addresses when new (trusted) clients appear on the network.

To add a new MAC address:

1. Click the Server/Security tab.
2. Choose Preload MAC Addresses from the drop-down list.
3. Choose [New Record].
4. Enter a value for each parameter.
5. Click Add.

Changes to the database take effect immediately.

Removing a MAC Address

To remove a MAC address:

1. Click the Server/Security tab.
2. Choose Preload MAC Addresses from the drop-down list.
3. Choose the MAC address you want to delete.
4. Click Delete.

Changes to the database take effect immediately.

Searching for a MAC or IP Address

To search for a MAC or IP address:

1. Click the Server/Security tab.
2. Choose Preload MAC Addresses from the drop-down list.
3. Click Find.
4. Enter the MAC or IP address you want to locate.
5. Click OK.

Refreshing the MAC Addresses Window

To refresh the MAC address window so that it reflects the current status of the database, click Refresh.

DHCP allows you to configure many client parameters in addition to the client's IP address. For example you can configure the IP address of a client's bind server and its DNS domain name.

There are three ways to assign configuration parameters to DHCP clients. You can assign parameters to:

• A specific client
  To assign parameters to a specific client, use the node configuration options described in Section 8.5.3.2. This is called a node group and is identified by the client's MAC address.
• A net or subnet
  To assign parameters to all clients in a subnet, use the subnet configuration options described in Section 8.5.3.1. This is called a subnet group and is identified by the subnet in which the client is being configured. You will likely configure each client within a subnet with similar parameters, for example, DNS domain name, DNS server, default route, and so forth.
• A group of clients
  To assign parameters to a group of clients that are not in the same subnet, use the group configuration options described in Section 8.5.3.3. This is called an include group. You can declare a node or subnet group as a member of an include group to pull in the include group's parameters.

After the DHCP server finds an IP address for a client, it matches the client's MAC address against your node groups and the client's subnet against your subnet groups, pulling any parameters from matched groups into the list of parameters to be sent to the DHCP client. If a match occurs against both a subnet and a node group, and a particular parameter is assigned in both the subnet and the node group, then the value from the node group is used. When a match occurs on a subnet or node group that is a member of an include group, the DHCP server pulls in parameters from the include group also.

8.5.3.1 The Subnets Tab

A subnet is a segment of a logical network that has been divided into smaller physical networks. Use the Subnets tab to configure parameters to be passed to DHCP clients according to the subnet in which they reside.

8.5.3.1.1 Configuring a Subnet

You do not have to change every value for the parameters in the Subnets tab.

To configure a subnet group using the Subnets tab, use the following procedure. For a description of the subnet parameters, see Section 8.5.3.4.

1. Click the Subnets tab.
2. Choose [New Record].
3. Choose the Name parameter from the Name/ID Parameters menu.
4. Enter the name of the subnet configuration in the Value field. This name is a tag for internal use of the DHCP server only. For more information, see Section 8.5.3.4.1.
5. Choose Member of Group (optional). Enter the name of the include group that the subnet group is joining. Any client that matches this entry will pull in the parameters from the specified include group.
6. Set up key information:
   1. Choose the net or subnet IP address.
      Enter the net or subnet IP address that identifies the subnet portion of the network.
   2. Choose the vendor class (optional).
      Enter the vendor class (for example, TCPVMS or JOIN) that identifies the DHCP client vendor class to which this entry should apply. Note that you can have multiple subnet entries for the same Net or Subnet IP Address if they have different Vendor Class key values. If the entry should apply to any vendor class or you are not using vendor classes leave the Vendor Class field blank.
7. Choose from the lists of DHCP parameters on the drop-down list.
   Different lists of DHCP parameters are available on the drop down list. Choose either BASIC DHCP Parameters or DHCP Parameters.
8. 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 8.5.3.4.
9. Choose Update from the File menu to update the server with the new configuration.

The new configuration takes effect immediately.

8.5.3.1.2 Removing a Subnet Record

To remove a subnet record:

1. Click the Subnets tab.
2. Choose DHCP Parameters from the drop-down list.
3. Choose the subnet record you want to delete.
4. Click Delete.

Changes to the database take effect immediately.

8.5.3.2 The Nodes Tab

A node is a workstation, computer, or other device on the network. Use the Nodes tab to configure parameters to be passed to specific client nodes.

8.5.3.2.1 Configuring a node

You need not change every value for the parameters in the Nodes tab. A node group can be a member of an include group although the settings for a node group override those from a subnet or include group.

To configure a node group using the Nodes tab, use the following procedure. For a description of the node parameters, see Section 8.5.3.4.

1. Click the Nodes tab.
2. Choose [New Record].
3. Enter the name of the node configuration in the Value field. This name is a tag for internal use of the DHCP server only. For more information, see Section 8.5.3.4.1.
4. Choose Member of Group (optional). Enter the name of the include group that the node group is joining. The client that matches this entry will pull in the parameters from the specified include group.
5. Set up key information:
   1. Choose Hardware Address. Enter either the hardware address or the client ID of the node.
      If you are using the hardware address (MAC address) of the node, enter it using the format xx:xx:xx:xx:xx:xx, for example, 00:08:C7:08:E3:63. The hardware address is assigned during manufacturing, and usually appears when you turn on or reboot your computer.
   2. Choose Hardware Type. Enter the type of network the node is connected to: Token Ring, Ether3, Pronet, ARCnet, or 0 (see Table 8-6).
6. Choose from the lists of DHCP parameters on the drop-down list.
   Different lists of DHCP parameters are available on the drop-down list. Choose either BASIC DHCP Parameters or DHCP Parameters.
7. 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 8.5.3.4.
8. Choose Update from the File menu to update the server with the new configuration.

The new configuration takes effect immediately.

To remove a node record:

1. Click the Nodes tab.
2. Choose DHCP Parameters from the drop-down list.
3. Choose the Node record you want to delete.
4. Click Delete.

Changes to the database take effect immediately.