function showHelp(tl)
{
if(tl=="dhcp")
{
dw("<FONT><B>DHCP Server</B><A NAME=dhcp></A><BR>")
dw("<FONT SIZE=2>DHCP stands for Dynamic Host Control Protocol. The DHCP server gives out IP addresses when a device is starting up and request an IP address to be logged on to the network. The device must be set as a DHCP client to \"Obtain the IP address automatically\". By default, the DHCP Server is enabled in the unit. The DHCP address pool contains the range of the IP address that will automatically be assigned to the clients on the network.")
dw("<UL><I><B>IP Starting Address :</B></I> The starting IP address for the DHCP server's IP assignment.<BR>")
dw("<I><B>IP Ending Address :</B></I> The ending IP address for the DHCP server's IP assignment.<BR>")
dw("<I><B>Lease Time :</B></I>  The length of time for the IP lease.</UL><P><P></FONT>")
dw("<FONT SIZE=2>Static DHCP is used to allow DHCP server to assign the same IP to specific MAC address. This is useful when you setup public servers(Web Server, FTP Server, for instance) inside LAN.")
dw("<UL><I><B>Name:</B></I> The name referencing the static IP assignment.<BR>")
dw("<I><B>IP Address:</B></I> The IP address for the specific node in LAN.<BR>")
dw("<I><B>MAC Address:</B></I> The MAC address of the specific node in LAN.<BR>")
dw("<I><B>DHCP Client:</B></I> You can select from this list to choose the node you want to assign static IP to.<BR></UL><P>")
dw("The Static DHCP Clients List will display all the IP-MAC mappings you want to assign to specific nodes. DHCP client computers connected to the unit will have their information displayed in the Dynamic DHCP Clients List. The table will show the Host Name, IP Address, and MAC Address of the DHCP client computer.</FONT><P><P>")
}
if(tl=="spap")
{
dw("<FONT><B>Special Applications</B><A NAME=spap></A><BR>")
dw("<FONT SIZE=2>Some applications require multiple connections, like Internet games, video conferencing, Internet telephony and others. These applications have difficulties working with NAT (Network Address Translation). Special Applications allows some of these applications to work.")
dw("If you need to run applications that require multiple connections, specify the port normally associated with an application in the \"Trigger port\" field, select the protocol type as TCP (Transmission Control Protocol) or UDP (User Datagram Protocol),")
dw("then enter the public ports associated with the trigger port to open them for inbound traffic.")
dw("At the bottom of the screen, there are already defined well-known special applications. To use them, click on the edit icon and enable the service.")
dw("<P><UL><I><B>Name</B></I> :This is the name referencing the special application.<BR>")
dw("<I><B>Trigger Port</B></I> :This is the port used to trigger the application. It can be either a single port or a range of ports.<BR>")
dw("<I><B>Trigger Type</B></I> :This is the protocol used to trigger the special application.<BR>")
dw("<I><B>Public Port</B></I> :This is the port number on the WAN side that will be used to access the application. You may define a single port or a range of ports. You can use a comma to add multiple ports or port ranges.<BR>")
dw("<I><B>Public Type</B></I> :This is the protocol used for the special application.<BR></UL>")
dw("If the mechanism of Special Applications fails to make an application work, try using DMZ host instead.<P>")
dw("<I>NOTE: At any time, only one PC can use each Special Application</I>.</FONT><P><P>")
}
if(tl=="vpnIKE")
{
dw("<FONT><B>VPN Settings - IKE</B><A name=vpn1_ike></A></FONT><BR>")
dw("<FONT SIZE=2>There are three parts that are necessary to setup the configuration of IKE for the dedicated tunnel: basic setup, IKE proposal setup, and IPSec proposal setup.")
dw("Basic setup includes the setting of following items: local subnet, local netmask, remote subnet, remote netmask, remote gateway, and pre-shared key. The tunnel name is derived from previous page of VPN setting.")
dw("IKE proposal setup includes the setting of a set of frequent-used IKE proposals and the selecting from the set of IKE proposals. Similarly, IPSec proposal setup includes the setting of a set of frequent-used IPSec proposals and the selecting from the set of IPSec proposals.<BR>")
dw("<B>Basic setup</B>:<BR><UL><I><B>Aggressive Mode</B></I>:Enabling this mode will accelerate establishing tunnel, but the devicewill suffer from less security in the meanwhile. Hosts in both ends of the tunnel must support this mode so as to establish the tunnelproperly.<BR>")
dw("<I><B>Local subnet</B></I>:The subnet of LAN site of local VPN gateway. It can be a host, a partial subnet, and the whole subnet of LAN site of local gateway.<BR>")
dw("<I><B>Local netmask</B></I>:Local netmask combined with local subnet to form a subnet domain.<BR>")
dw("<I><B>Remote subnet</B></I>:The subnet of LAN site of remote VPN gateway, it can be a host, a partial subnet, and the whole subnet of LAN site of remote gateway.<BR>")
dw("<I><B>Remote netmask</B></I>:Remote netmask combined with remote subnet to form a subnet domain of remote end.<BR>")
dw("<I><B>Remote gateway</B></I>:The IP address of remote VPN gateway.<BR>")
dw("<I><B>IKE Keep Alive(Ping IP Address)</B></I>:Input the IP address of remote host that exist in the opposite side of the VPN tunnel (Ex. You can input the LAN IP address of remote VPN gateway). The device will start to Ping remote host when there is no traffic within the VPN tunnel. If the device can't get ICMP response from remote host anymore, then it will terminate the VPN tunnel automatically.<BR>")
dw("<I><B>Pre-shared key</B></I>:The first key that supports IKE mechanism of both VPN gateways for negotiating further security keys. The pre-shared key must be same for both end gateways.<BR>")
dw("<I><B>Extended Authentication (xAuth)</B></I>:With xAuth feature, the VPN client (or initiator) needs to provide additional user information to remote VPN server (or VPN gateway) for extended authentication. The VPN server would reject the connect request from VPN clients because of the unknown user, even though the pre-shared key is correct. Thisfunction is suitable to remote mobile VPN clients. You can not only configure a VPN rule with a pre-shared key for all remote users using, but you can also designate only someone is permitted to establish VPN connection with VPN server.<BR>")
dw("<I><B>Enable</B></I>:Check this checkbox to enable extended authentication with this rule.<BR>")
dw("<I><B>IPSec NAT Traversal</B></I>: IPsec NAT-T automatically determine during the IPsec negotiation process:1. Whether both the initiating IPsec (typically a client computer) and responding IPsec (typically a server) can perform IPsec NAT-T. 2. If there are any NATs in the path between them. If both of these conditions are true, each of the initiating IPsec and the responding IPsec will automatically use IPsec NAT-T to send IPsec-protected traffic across a NAT. If either them does not support IPsec NAT-T, then normal IPsec negotiations (beyond the first two messages) and IPsec protection is performed. If both them support IPsec NAT-T and there are no NATs between them, normal IPsec protection is performed.<BR>")
dw("<I><B>Remote ID</B></I>: The Type and the Value are must same as the Type and the Value of the Local ID of the remote VPN gateway.<BR>")
dw("<I><B>Local ID</B></I>: The Type and the Value are must same as the Type and the Value of the Remote ID of the remote VPN gateway.<BR>")
dw("<I><B>Server mode</B></I>:Check this checkbox if the device behaves as a VPN server, and will verify the legality of user information from VPN client. The user information that is provided by VPN client needs to match to user information that is in local user database of VPN server. You can press \"Set local user\" button to edit local user database. Please note that only VPN clients with xAuth can establish VPN connection with the device if you have checked this checkbox.<BR>")
dw("<I><B>Client mode</B></I>:Check this checkbox if the device behaves as a VPN server, and will send user information to remote VPN server for extended authentication. You need to input correct user name and password to pass authentication. Please note that remote VPN server which is without xAuth will reject your connect request if you have checkedthis checkbox.<BR>")
dw("<I><B>User Name</B></I>:Input user name that is provided by remote VPN server. This field is for xAUTH client mode use only. <BR>")
dw("<I><B>Password</B></I>:Input password that is corresponded to the user name above. This field is for xAUTH client mode use only.<BR>")
dw("<I><B>Select IKE proposal...</B></I>:Click the button to setup a set of frequent-used IKE proposals and select from the set of IKE proposals for the dedicated tunnel.<BR>")
dw("<I><B>Select IPSec proposal...</B></I>:Click the button to setup a set of frequent-used IPSec proposals and select from the set of IKE proposals for the dedicated tunnel..<BR></UL><P>")
dw("<FONT><B>VPN Settings - xAuth - Set Local User </B><A name=xAuth></A></FONT><BR>")
dw("<font SIZE=2>You can edit user information with this configuration page. These user information is for xAuth server mode use only.</FONT><BR></UL><P>")
}
}