Not able to get an IP address for GVC virtual adapter

This article provides more information about issues encountered when trying to get an IP address for the virtual adapter when using the SonicWall Global VPN Client (GVC).
There are a number of reasons why the virtual adapter may fail to retrieve an IP address. This document will discuss some of the more common reasons and provide some procedures to resolve these issues.

Verify settings on the SonicWall firewall

• Settings on SonicWall's DHCP server

1. Login to the SonicWall management Interface, navigate to MANAGE| Network | DHCP Server. 
2. Make sure Enable DHCPv4 Server  under DHCPv4 Server Settings is checked. 
3. Make sure that there is a dynamic lease scope is defined that is assigned to LAN (LAN by default in SonicOS Standard, X0 by default in SonicOS Enhanced).
4. Make sure Enable under DHCPv4 Server Lease Scopes is checked.
   

Settings on WAN Group VPN

1. Navigate to MANAGE | VPN  Base Settings, click configure for WAN group VPN (for Enhanced OS and Group VPN for Standard OS).
2. VPN policy window is displayed , navigate to the Client tab .Make sure that virtual adapter settings is set to DHCP lease.
   
   
   

 
Settings on DHCP over VPN

1. Navigate to MANAGE | VPN | DHCP over VPN ,Make sure that central gateway is selected.
2. Click on the configure button for central gateway , DHCP over VPN configuration windows is displayed.
3. Make sure that Use Internal DHCP Server and For Global VPN client check boxes are checked.(If SonicWall is the DHCP server).
4. If you are using an external DHCP server, the DHCP server can be on the primary LAN network or on a routed network from the Primary LAN interface. Ensure the following settings on your firewall are properly configured.

• Configure the external DHCP server with a scope to assign DHCP lease from to GVC clients.
• If the DHCP scope is the SAME as the Primary LAN network then no additional steps are required.
• If the DHCP scope is not the same as the Primary LAN network, then configure the Relay IP address.
  

Verify settings on the GVC software

• ESP Traffic is Blocked
  SonicWall GVC may be run from behind a firewall or other device that allows ISAKMP traffic to pass through, but does not allow ESP traffic to pass through. The DHCP requests that get sent for the virtual adapter are sent down the tunnel like any other traffic and are thus encapsulated in ESP. The ESP packets are simply dropped by the firewall with no indication back to GVC.To work around this problem, GVC is enabled to detect a NAT device in the middle. When GVC detects a NAT device, it encapsulates all ESP traffic (including DHCP packets) using the UDP header. The UDP header uses the same port as ISAKMP control traffic. Therefore the Peer must separate the IKE control traffic from the data traffic.
  
  To configure the NAT traversal setting from the client, select the Connection in GVC and then select File | Properties. Select the Peers tab and then select the appropriate peer (head-end firewall) and choose Edit. Next choose NAT Traversal and select Forced On.

• NAT Traversal UDP Encapsulated ESP Traffic is Blocked
  Occasionally GVC may be run from behind a NAT device that improperly handles NAT traversal packets (ESP packets encapsulated in ISAKMP). These packets are discarded by the NAT device without any notification sent back to GVC.To work around this problem, set GVC never to perform NAT traversal. This means that ESP traffic will not be encapsulated in UDP. In order for this to work, the NAT device must be in ‘IPSec pass-through’ mode. This mode will prevent multiple GVC clients running simultaneously behind a single NAT device.
  To disable NAT traversal in the client, select the Connection in GVC and then select File | Properties. Select the Peers tab and then select the appropriate peer (head-end firewall) and choose Edit. Next choose NAT Traversal and select Disabled.

Verify settings on the Workstation

1. Make sure that the SonicWall LAN subnet and workstation IP address are not in the same subnet.
2. Try disabling the firewall and antivirus applications on the workstation. If you are running a client-based software firewall on the Vista machine, check if the version is Vista compatible. If it is not, then upgrade to the latest version. If it does not work after the upgrade then add a rule to allow TCP/UDP port 67/68. If this does not fix the problem then go to step C.
   
   

   NOTE: There were numerous problems reported with Norton Internet Security Suite. If you have this software installed then the final try is to Uninstall Norton and reboot your computer and then try again.

3. Verify that no 3^rd party IPSec VPN clients are installed on your computer. Uninstall any existing IPSec VPN clients (including GVC), reboot, and then install GVC again.
4. Make sure that the virtual adapter is not assigned with any static IP address.
5. Make sure that the UDP ports 500 and 4500 is opened on the upstream device / Router.
6. Verify DNE binding is enabled for the SonicWall Virtual Adapter. Go to Start|Control Panel|Network and Internet|Network and Sharing Center|Mange network connections page. Select SonicWall Virtual Adapter and right click on properties. On the properties page verify Deterministic Network Enhancer binding is enabled. 
7. Dell Wireless WLAN 4.10+ wireless network driver includes VLAN Priority Support which conflicts with getting a DHCP lease for the SonicWall Virtual Adapter. Check if VLAN Priority Support is enabled. If it is, disable it by performing the following steps:

• Right-click My Computer on the desktop and click Properties. NOTE: If there is no My Computer icon on the desktop, click Start and right-click My Computer on the right column of the Start menu. 
• When the System Properties window appears, click the Hardware tab and click Device Manager.
• When the Device Manager window appears, click the <+> next to Network Adapters and double-click Dell Wireless WLAN Adapter.
• When the Dell Wireless WLAN Adapter Properties window appears, click the Advanced tab.
• Scroll down to VLAN Priority Support and click to highlight.
• Select Disable from the drop-down menu under the Value: field.
• Click OK to close the Dell Wireless WLAN Adapter Properties window.
• Click the X button in the upper right-hand corner of the Device Manager window to close it.