DHCP Server

The DHCP (Dynamic Host Configuration Protocol) ISPs use the DHCP to assign mobile clients an IP address that is good only for the duration of a dial-in phone call. Server automates the process of assigning IP addresses to host systems on locally attached networks. Additionally, a DNS server and default gateway can be provided by the DHCP server. The DHCP server manages a range of IP addresses (e.g., 10.10.10.4ñ10.10.10.254) which can be assigned to clients. Non-contiguous addresses can be defined using exclusion ranges. Exclusion ranges indicate which IP addresses within the previously defined address range are not to be assigned to host systems by the DHCP server.

When the DHCP Server receives an initial request from a client host, it assigns an available IP address from its pool. Upon subsequent requests by the same client, the DHCP server will attempt to reassign the same IP address. The only case in which it will not reassign the same IP address is when the number of clients exceeds the number of addresses in the pool, and the IP address was assigned to a different host.

Changes to DHCP will not be applied until the section is saved. If a network connection is established and the section is saved, the DHCP Server changes will be applied immediately to the GTA Firewall.

In GBAdmin, first click the ENABLE checkbox to allow DHCP to be edited, then click ADD + to insert a DHCP service. Select the inserted line. Once the fields have been saved, the basic information will appear in the DHCP service line below. To add an exclusion range, click ADD + next to the EXCLUSION fields. This will create a blank IP address for both the beginning and ending of the range. Double-click within the field to edit the BEGINNING IP address. Delete any extra characters, then edit the ENDING field.

Add a DHCP Service

First enable the service to allow it to be edited, then click Add (+) to insert a DHCP service. Select the line to open the editing fields. Once the fields have been edited and saved, the basic information will appear in the DHCP service line below.

Add an Exclusion Range

To add an exclusion range, click Add (+) next to the Exclusion fields. This will create a blank IP address for both the beginning and ending of the range. Double-click within the field to edit the Beginning IP address. Delete any extra characters, then edit the Ending field.

Enable Select this checkbox to enable the currently displayed DHCP IP address pool.
 

Description Enter a description of the currently displayed DHCP IP address pool.
 

Beginning Address First IP of a block of IPs that will be assigned.
 

Ending Address Last IP of a block of IPs that will be assigned.
 

Netmask Netmask to assign to DHCP clients.

Lease Duration Enter the maximum time the DHCP address is valid for use by a requesting client. A client must negotiate to reuse the assigned address before the end of the lease time or quit using the address.
 

Exclusion Define up to five ranges of addresses to exclude from Ranges being assigned within each DHCP address range. To exclude a single IP, enter the IP address to be excluded in both the beginning and ending address fields.

Domain Name The DNS domain name, typically, that of the local network.

Name Server Enter the IP address of a DNS server that will be issued IP address to the requesting client. This IP can be any valid server: a local server, such as the built-in GNAT Box DNS server, or a remote server, such as one located at an ISP. Up to three name servers can be defined.

Default Gateway The IP address that the requesting clients will use for their default gateway The gateway (default route) is generally the router IP address that connects the network to the Internet. The default route is the gateway where any non-local IP packets are sent. If you have selected the PPP device or enabled DHCP or PPPoE on an external network interface, then the Default Route field will be disabled; this value will be set by the selected protocol (PPP, PPPoE or DHCP). A default route must always be on the same logical network as the External network interface, the only exception being a GTA Firewall PPP connection. (default route). For hosts located behind a GTA Firewall (on Protected or PSNs) this value will be the IP address of the GTA Firewall NIC where the network is attached (e.g., if the client is located on the Protected Network, then the default gateway will be the Protected Network's' IP address).

¨ Notes

If the DHCP service is for an External Network then the default gateway is most likely the Internet router An internetworking switch operating at the OSI Level 3, the Network Layer.'s IP address.

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