AT&T Uverse/Configuring Ip Passthrough and DMZ plus

https://www.att.com/support/smallbusiness/article/smb-internet/KM1188700/

When configured for IP Passthrough (Passthrough Mode) the AT&T provided gateway shares its Dynamic WAN IP address with a single device on the LAN.

About Configuring IP Passthrough and DMZplus
This configuration is often suitable for a customer desiring to connect third party equipment for networking, such as a router, to the AT&T provided gateway. IP Passthrough is also commonly used as an alternative to using a bridged mode. Note the following before configuring passthrough mode:


 * Only one device can be put into passthrough mode.
 * Placing a device in passthrough mode will remove firewall protection provided by the AT&T gateway.
 * When a device is configured in passthrough mode, it will be assigned a WAN IP instead of a LAN IP. Other devices connected to your gateway may no longer be able to share files with the device in passthrough mode.

You will first need to locate your AT&T equipment to determine if you have a Motorola or 2Wire/Pace device. Then connect a PC directly to the AT&T gateway with Ethernet and follow the instructions below.

Motorola NVG 510 and 589
The Motorola RG can be configured in three ways to pass the DHCP WAN IP address to a device on the LAN.


 * DHCPS-dynamic: The public WAN IP address is delivered by the AT&T provided RG's DHCP server to the first device that requests a DHCP address on the LAN.
 * DHCPS-fixed: The public WAN IP address is delivered by the device's DHCP server to the device whose MAC address has been specified.
 * Manual: A LAN device must be manually configured with the AT&T provided device's assigned WAN IP address and gateway information. To use this method, you will need to contact Customer Care to obtain your Wan IP Address, default gateway, and subnet mask.

DHCPS-dynamic

 * Open a browser on a computer that is directly connected to the gateway.
 * In the address bar, enter http://192.168.1.254.
 * Select the Firewall tab in the RG GUI page.
 * Select IP Passthrough below the Firewall tab.
 * Enter the Device Access Code if prompted.
 * Select the Passthrough option from the Allocation Mode drop-down menu.
 * Select DHCPS-dynamic from the Passthrough Mode drop-down.
 * Select Save. A re-starting gateway reminder message appears.
 * Select Restart Now to complete the setting change.
 * Refresh the network connection on the device that is to be set up to receive the public IP address. Typically this can be done with a power cycle of the device.

Note: The device you are putting into passthrough mode must be configured to obtain an IP address through DHCP for the DHCP-dynamic option to work. If the gateway is reset using this mode, the first device that makes a DHCP request will be put into passthrough mode. If you plan to have more than one device connected directly to the ATT gateway, then using DHCP-fixed option is recommended.

DHCPS-fixed

 * Open a browser on a computer that is directly connected to the RG.
 * In the address bar, enter http://192.168.1.254.
 * Select the Firewall tab in the RG GUI page.
 * Select IP Passthrough below the Firewall tab.
 * Enter the Device Access Code if prompted.
 * Select the Passthrough option from the Allocation Mode drop-down menu.
 * Select DHCPS-fixed from the Passthrough Mode drop-down.
 * Enter the MAC address of the device that is to be set up to receive the public IP address in the Passthrough Fixed MAC Address field.
 * Select Save. A re-starting gateway reminder message appears.
 * Select Restart Now to complete the setting change.
 * Refresh the network connection on the device that is to be set up to receive the public IP address. Typically this can be done with a power cycle of the device.

Note: The device you are putting into passthrough mode must be configured to obtain an IP address through DHCP for the DHCP-fixed option to work. Show more

Manual

 * Open a browser on a computer that is directly connected to the RG.
 * In the address bar, enter http://192.168.1.254.
 * Select the Firewall tab in the RG GUI page.
 * Select IP Passthrough below the Firewall tab.
 * Enter the Device Access Code if prompted.
 * Select Passthrough option from the Allocation Mode drop-down menu.
 * Select manual from the Passthrough Mode drop-down.
 * Select Save. A re-starting gateway reminder message appears.
 * Select Restart Now to complete the setting change.
 * Manually configure your device to use the WAN IP address, default gateway, and Subnet mask provided to you by customer care.

Note: The WAN IP, default gateway, and subnet mask the AT&T gateway is sharing are assigned to the gateway through DHCP. If AT&T gateway receives a different WAN IP, you will lose connectivity on your device until you manually update its settings. Using the DHCP-fixed option is recommended.

Default Server
Motorola gateways also include an option to use Default Server mode. Default Server mode allows the AT&T provided gateway to forward all externally initiated IP traffic (TCP and UDP protocols only) to a specified device (default host) on the LAN. A device configured for a default server will continue to receive a LAN IP address, instead of being assigned a WAN IP.

Configuring Default Server Allocation Mode

 * Open a browser on a computer that is directly connected to the RG.
 * In the address bar, enter http://192.168.1.254.
 * Select the Firewall tab in the RG GUI page.
 * Select IP Passthrough below the Firewall tab.
 * Enter the Device Access Code if prompted.
 * Select the Default Server option from the Allocation Mode drop-down menu.
 * Enter the IP address of the Device to be set as the default server in the Default Server Internal Address field.
 * Select Save. A re-starting gateway reminder message appears.
 * Select Restart Now to complete the setting change.

2Wire/Pace Gateways
The passthrough mode for 2Wire/gateways in referred to as DMZplus mode. The device that you would like to be placed in DMZplus must be connected directly to the gateway and configured to obtain an IP address through DHCP.


 * Open a browser on a computer that is directly connected to the RG.
 * In the address bar, enter http://192.168.1.254.
 * In the GUI select Settings, then Firewall, and then Applications, Pinholes, and DMZ.
 * Under Select a Computer, click the device name or IP address of the device you wish to put in DMZplus mode.
 * Select the Allow all Applications(DMZplus mode) radio button.
 * Select Save.

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