DHCP Global

The global page is used to enable the DHCP service and set its mode of operation.

The DHCP service is activated on a per-interface basis - to activate DHCP for a particular interface, select the interface's tick-box control in the Interfaces region. Click the Save button to save all configuration changes.

DHCP Server

The dhcp server page is used to configure automatic dynamic and static IP leasing to DHCP requests received from network hosts.

The DHCP service allows up to 20 named DHCP subnets to be configured. Each subnet can have a number of dynamic and static IP ranges defined. To create a DHCP subnet, use the following configuration controls to define the subnet and DHCP host settings:

• Network - Defines the subnet. An arbitrary IP address that specifies the a part of the network ID when combined with the Netmask value, e.g. "192.168.10.0".
• Netmask - Defines the subnet. A value used to identify the network ID from the host ID of an arbitrary IP address, e.g. "255.255.255.0"
• Primary DNS - Used to set the value that a requesting network host will receive for the primary DNS server it should use.
• Secondary DNS - Used to set the value that a requesting network host will receive for the secondary DNS server it should use.
• Primary WINS - Used to set the value that a requesting network host will receive for the primary WINS server it should use. This is often not required on very small Microsoft Windows networks.
• Secondary WINS - Used to set the value that a requesting network host will receive for the secondary WINS server it should use. This is often not required on very small Microsoft Windows networks.
• Default lease time (mins) - Used to set the lease time assigned to network hosts that do not request a specific lease time. The default value is usually sufficient.
• Max lease time (mins) - Used to set a lease time limit to prevent network hosts requesting (and being granted) impractically long DHCP leases. The default value is usually sufficient.
• Default gateway - Used to set the value that a requesting network host will receive for the default gateway it should use.
• Domain name suffix - Used to set the domain name suffix that will be appended to the requesting host's hostname.
• Enabled - Determines whether the DHCP subnet is currently active.

To create a new DHCP subnet, choose a DHCP subnet profile with an "Empty" value from the DHCP Subnetdrop-down menu. Enter an appropriate name for the DHCP subnet in the Subnet name text field, for example "Admin office DHCP subnet". Enter appropriate configuration values into each of the configuration controls outlined above and click the Save button in the Settings region. Dynamic and static ranges can now be added to the DHCP subnet.

Note - If the SmoothWall system is running the DNS proxy service, the DNS server values should be left to use the default values for the primary and secondary DNS servers. If you run a local DNS server and want your desktops to use it, set the Secondary DNS to its address.

To delete a DHCP subnet, choose the DHCP subnet to be deleted from the DHCP Subnet drop-down menu and click the Delete button.

Choose the DHCP subnet to add a dynamic range to from the DHCP Subnet drop-down menu and click the Select button. Use the following configuration controls in the Add a new dynamic range region:

• Start address - The start of an IP range over which the DHCP server should supply dynamic addresses from. This address range should not contain the IPs of other machines on your LAN with static IP assignments.
• End address - The end of an IP range over which the DHCP server should supply dynamic addresses to. This address range should not contain the IPs of other machines on your LAN with static IP assignments.
• Comment - A text-field used to assign a helpful message describing the dynamic range.
• Enabled - Determines whether the dynamic range is currently active.

Enter appropriate values into each of the configuration controls outlined above and click the Add dynamic range button.

Choose the DHCP subnet from the DHCP Subnet drop-down menu and click the Select button. To remove one or more dynamic ranges from the DHCP subnet, locate each rule within the Current dynamic rules region and select their adjacent Mark tick-box controls. Click the Remove dynamic range button.

Choose the DHCP subnet from the DHCP Subnet drop-down menu and click the Select button. To edit a particular dynamic range, locate it within the Current dynamic rules region and select its adjacent Mark tick-box control. Click the Edit dynamic range button to populate the configuration controls in the Add a new dynamic range region with its current configuration values. Alter the configuration values as necessary, and click the Add dynamic range button.

Note - Failure to click the Add dynamic range button will result in the loss of the dynamic range.

Static assignments are used to allocate fixed IP addresses for nominated network hosts. It does this by referencing the unique MAC address of the host NIC. This is useful for ensuring that certain hosts always get the same IP address despite using DHCP, as if they had been configured with a static IP address.

To create static assignments, use the following configuration controls in the Add a new static assignment region:

• MAC address - Used to set the MAC address of the network host's NIC. This is entered as six pairs of hexadecimal numbers, with a space, colon or other separator character between each pair, e.g. 12 34 56 78 9A BC or 12:34:56:78:9A:BC
• IP address - The IP address that is assigned to the network host with the specified MAC address.
• Comment - A text-field used to assign a helpful message describing the static assignment.
• Enabled - Determines whether the static assignment is currently active.

Choose the DHCP subnet from the DHCP Subnet drop-down menu and click the Select button. To remove one or more static ranges from the DHCP subnet, locate each rule within the Current static rules region and select their adjacent Mark tick-box controls. Click the Remove static button.

Choose the DHCP subnet from the DHCP Subnet drop-down menu and click the Select button. To edit a particular static assignment, locate it within the Current static assignments region and select its adjacent Mark tick-box control. Click the Edit static button to populate the configuration controls in the Add a new static assignment region with its current configuration values. Alter the configuration values as necessary, and click the Add static button.

Note - Failure to click the Add static button will result in the loss of the static assignment.

The DHCP service can detect visible MAC and IP addresses on the network using the ARP cache. A list of network hosts along with these details is displayed in the Add static assignment from ARP table region. This can be used as a simple configuration alternative to manually creating static assignments.

To create a static assignment using the ARP table records for one or more hosts, locate each ARP table entry within the Add static assignment from ARP table region and select their adjacent Mark tick-box controls. Click the Add static from ARP table button.

Choose the DHCP subnet to be viewed from the DHCP Subnet drop-down menu and click the Select button. The DHCP subnet's dynamic ranges and static assignments are listed in the Current dynamic ranges and Current static assignments regions in table format.

DHCP Leases

The dhcp leases page is used to view all current DHCP leases, including IP address, MAC address, hostname, lease start and end time, and the current lease state.

Current DHCP leases can be viewed in the DHCP leases region by clicking the Update button. The following information is displayed:

• IP address - The IP address assigned to the network host that submitted a DHCP request.
• MAC address - The MAC address of the network host that submitted a DHCP request.
• Hostname - The Hostname assigned to the network host that submitted a DHCP request.
• Start time - The start time of the DHCP lease granted to the network host that submitted a DHCP request.
• End time - The end time of the DHCP lease granted to the network host that submitted a DHCP request.
• State - The current state of the DHCP lease. The state can be either 'Active' (currently leased) or 'Free' (the IP address is reserved for the same MAC address or re-used if not enough slots are available).

To show 'Free' leases in addition to 'Active' ones, select the Show free leases tick-box and click the Update button.