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The default setting is 8.
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.
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.
The default minimum packet size is 300 bytes.
DNS is the only name service available with TCP/IP Services.
The following are valid values:
False: | Do not send an ICMP echo request to a BOOTP client before assigning an IP address. Default. |
True: | Send an ICMP echo request to a BOOTP client before assigning an IP address. |
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.
The default is 1 minute.
The following are valid values:
False: | Do not reply (the server should hear the client broadcast directly). Default. |
True: | Reply no matter where the agent is located (the value in giaddr field). |
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:
False: | Do not allow manual assignment of MAC addresses. Default. |
True: | Allow manual assignment of MAC addresses. |
The following are valid values:
False: | Send a minimum configuration. Default. |
True: | Send a complete configuration. |
The following are valid values:
False: | Ignore a BOOTP packet with a MAC address of 16 octets. Default. |
True: | Recognize a BOOTP packet with a MAC address of 16 octets. |
The following are valid values:
False: | Use client ID to identify clients. Default. |
True: | Use MAC address to identify clients. |
Use the IP Ranges parameters to specify the IP addresses that are available to assign to clients.
If your network contains subnets, that information must be included in the NETMASKS. file. See Section 8.2.2.4 for more information on the use of netmasks when you are using subnet addressing. |
To configure the server IP ranges:
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:
- Enter the beginning of the IP Address Range for the subnet: network, subnet, and host address.
- Enter the end of the IP Address Range.
- 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.
Follow the instructions in this section only if the Accept Client Name parameter is set to False. |
To configure a host name:
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.Host Name 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:
- Click the Server/Security tab.
- Choose Active IP Snapshot from the drop-down list.
- Select a record on the left side of the window.
- 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:
- Click the Server/Security tab.
- Choose Active IP Snapshot from the drop-down list.
- Choose [New Record].
- Enter a value for each parameter.
- 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:
- Click the Server/Security tab.
- Choose Active IP Snapshot from the drop-down list.
- On the left side of the window, select the record you want to remove.
- 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:
- Click the Server/Security tab.
- Choose Preload MAC Addresses from the drop-down list.
- 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:
- Click the Server/Security tab.
- Choose Preload MAC Addresses from the drop-down list.
- Choose [New Record].
- Enter a value for each parameter.
- Click Add.
Changes to the database take effect immediately.
Removing a MAC Address
To remove a MAC address:
- Click the Server/Security tab.
- Choose Preload MAC Addresses from the drop-down list.
- Choose the MAC address you want to delete.
- Click Delete.
Changes to the database take effect immediately.
Searching for a MAC or IP Address
To search for a MAC or IP address:
- Click the Server/Security tab.
- Choose Preload MAC Addresses from the drop-down list.
- Click Find.
- Enter the MAC or IP address you want to locate.
- 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:
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.
The new configuration takes effect immediately.
8.5.3.1.2 Removing a Subnet Record
To remove a subnet record:
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.
The new configuration takes effect immediately.
Symbol | Number | Network Type |
---|---|---|
ethernet or ether | 1 | 10 MB Ethernet |
ethernet3 or ether3 | 2 | 3 MB experimental |
ax.25 | 3 | AX.25 Amateur Radio |
protnet | 4 | Protnet proNET Token Ring |
chaos | 5 | Chaos |
token-ring,tr,ieee802 | 6 | IEEE802 |
arcnet | 7 | ARCnet |
To remove a node record:
Changes to the database take effect immediately.
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