88The Host Hardware Address field displays. Here you enter the MAC address of the desig-nated IP-Passthrough computer.• If this MAC address is not all zeroes, then it will use DHCP to set the LAN host'saddress to the (configured or acquired) WAN IP address.The MAC address must be six colon-delimited or dash-delimited sets of hex digits ('0' –'FF').• If the MAC address is all zeroes, then the LAN host will have to be configured manually.Once configured, the passthrough host's DHCP leases will be shortened to two minutes.This allows for timely updates of the host's IP address, which will be a private IP addressbefore the WAN connection is established. After the WAN connection is established andhas an address, the passthrough host can renew its DHCP address binding to acquire theWAN IP address.A restriction. Since both the Gateway and the passthrough host will use the same IPaddress, new sessions that conflict with existing sessions will be rejected by the Gateway.For example, suppose you are a teleworker using an IPSec tunnel from the Gateway andfrom the passthrough host. Both tunnels go to the same remote endpoint, such as the VPNaccess concentrator at your employer’s office. In this case, the first one to start the IPSectraffic will be allowed; the second one – since, from the WAN, it's indistinguishable – willfail.
