DHCP interfaces

Navigate to Network > DHCP Interfaces to configure the DHCP settings for different interfaces on your LANCOM R&S^®Unified Firewall.

Input box	Description
I/0	A slider button indicates whether the DHCP server or the DHCP relay is currently enabled (I) or disabled (0). Click on the slider button to change the status of this option.
Mode	Select whether you wish to set up a DHCP server or a DHCP relay for this interface. The remaining fields on the screen depend on the selected operating mode.
Interface	Select the interface for which you want to make settings.

DHCP server settings

Operating the DHCP server on your LANCOM R&S^®Unified Firewall enables you to assign IP addresses to clients on the network and also to transfer additional configuration parameters (gateway, DNS server, NTP server, etc.) to these clients. Alternatively, DHCP requests can be transferred to a DHCP server in another network.

Configure the settings for the DHCP server of an interface on the following tabs:

On tab General:

Input box	Description
Network	From the drop-down list, select the subnet with IP addresses that were distributed by the DHCP server. By selecting the subnet, the input fields Range Start IP and Range End IP are automatically filled in with the respective IP range.
Range Start IP	If the pre-populated start IP address does not meet your needs, you can edit the entry to specify the range of IP addresses to distribute to client computers.
Range End IP	If the pre-populated end IP address does not meet your needs, you can edit the entry to specify the range of IP addresses to distribute to client computers.
Gateway	If the pre-populated gateway address to be passed on to the client does not meet your requirements, you can edit the entry. The gateway's default IP address is usually the IP address of your LANCOM R&S^®Unified Firewall.
Preferred DNS server / Alternative DNS server	If your LANCOM R&S^®Unified Firewall does not perform name resolution, specify DNS servers that are on the network or on the Internet. Otherwise the clients receive the IP addresses from your LANCOM R&S^®Unified Firewall as a DNS server.
Lease Time	Enter the time in minutes for a computer’s IP address to remain valid. The standard lease time is `60` minutes.
Maximum Lease Time	Enter the maximum lease time in minutes.
Preferred NTP server / Alternative NTP server	Optional: Clients can use NTP servers to determine the exact time. This is especially important for user authentication via Windows servers.
WINS server	Optional: If you have a WINS server in your network, inform the clients about this using this input field.
DNS Search Domains	Enter a DNS search domain that the DNS service will use to resolve host names that are not fully qualified domain names. Click on to add the DNS search domain to the list. You can edit or delete any entry in the list by clicking on the appropriate icon. Please refer to Icons and buttons for further information. Important: When you edit an entry, a checkmark will appear to the right of the entry. Click the checkmark to accept the change.

On tab Advanced:

Input box	Description
Authoritative	If enabled, the firewall is considered the authoritative DHCP server, i.e. only the addresses assigned by the firewall are valid for this network segment. This option is relevant for mobile devices.
Prevent IP Conflicts	Check this box so that the DHCP server pings an IP address to ensure that it is not in use before assigning it to a new client.
TFTP server address	Specify the IP address to the boot configuration file.
PXE filename	Enter the path and file name for the boot configuration file.
Proxy configuration address	Enter the URL for the proxy configuration in the browser.
Routes	Use this to communicate routes, i.e. the specification of a network with the corresponding gateway, to the clients.

On tab Static IP Addresses:

Input box	Description
MAC Address / IP Address / Host Name	Set a static IP address for a host on the network by entering the host's MAC address and IP address. You can also enter the host name. Click on Add to add the static IP address to the list. You can edit or delete any entry in the list by clicking on the appropriate icon. Please refer to Icons and buttons for further information. Important: When you edit an entry, a checkmark will appear to the right of the entry. Click the checkmark to accept the change.
Add from ARP Cache	From the drop-down list, select the addresses you wish to add from the ARP cache.

Input box

Description

MAC Address / IP Address / Host Name

Set a static IP address for a host on the network by entering the host's MAC address and IP address. You can also enter the host name. Click on Add to add the static IP address to the list. You can edit or delete any entry in the list by clicking on the appropriate icon. Please refer to Icons and buttons for further information.

Important: When you edit an entry, a checkmark will appear to the right of the entry. Click the checkmark to accept the change.

Add from ARP Cache

From the drop-down list, select the addresses you wish to add from the ARP cache.

On tab Vendor Specific Options:

Input box	Description
Vendor Identifier	Here you can configure manufacturer-specific options (DHCP option 43). The ID has a maximum of 64 characters consisting of a-z, A-Z, 0-9 and _. This is used by the LANCOM Management Cloud to distribute the LMC domain, project ID and location to other LANCOM devices, such as access points.
Options	NameThe name of the option. This has a maximum of 64 characters consisting of a-z, A-Z, 0-9 and _. CodeNumber of the option that should be sent to the DHCP client. The option number describes the information transmitted, e.g. "43" for manufacturer-specific options. Note: You can find a list of all DHCP options in RFC 2132 – DHCP Options and BOOTP Vendor Extensions of the Internet Engineering Task Force (IETF). ValueWith this field you define the contents of the DHCP option. IP addresses are specified with the usual notation for IPv4 addresses, e.g. as "123.123.123.100", integer types are entered as normal decimal numbers, and strings as simple text. Multiple values in a single field are separated with commas, e.g. "123.123.123.100, 123.123.123.200". The maximum length of the field is 64 characters.

Input box

Description

Vendor Identifier 

Here you can configure manufacturer-specific options (DHCP option 43). The ID has a maximum of 64 characters consisting of a-z, A-Z, 0-9 and _. This is used by the LANCOM Management Cloud to distribute the LMC domain, project ID and location to other LANCOM devices, such as access points.

Options

NameThe name of the option. This has a maximum of 64 characters consisting of a-z, A-Z, 0-9 and _.
CodeNumber of the option that should be sent to the DHCP client. The option number describes the information transmitted, e.g. "43" for manufacturer-specific options.
Note: You can find a list of all DHCP options in RFC 2132 – DHCP Options and BOOTP Vendor Extensions of the Internet Engineering Task Force (IETF).
ValueWith this field you define the contents of the DHCP option. IP addresses are specified with the usual notation for IPv4 addresses, e.g. as "123.123.123.100", integer types are entered as normal decimal numbers, and strings as simple text. Multiple values in a single field are separated with commas, e.g. "123.123.123.100, 123.123.123.200". The maximum length of the field is 64 characters.

The buttons available at the bottom right of the edit box depend on whether you are adding a new DHCP interface or editing an existing one. For a new DHCP interface, click Create to add it to the list of DHCP interfaces, or Cancel to discard your changes. To edit an existing DHCP interface, click Save to save the changes or Reset to discard your changes. If no changes have been made, you can click Close to close the editing window.

DHCP relay settings

A DHCP relay forwards requests to a DHCP server to another network, since DHCP requests cannot be routed.

Input box	Description
DHCP Server IP Address	Specify here the IP address of the server to which DHCP requests are to be forwarded.

If you change any settings, click Save to store your changes or Reset to discard them. Then click Close to quit the editing window.

Click Activate in the toolbar at the top of the desktop to apply your configuration changes.