Create a VPN on your iPad, iPhone or iPod Touch and SonicWALL NSA UTM
This article will easily explain how to configure your Apple iPad, iPhone or iPod Touch to access your network by using the SonicWALL WAN GroupVPN Security Association and the built-in L2TP server. This relates to SonicOS Enhanced version 5.2.x (or newer) firmware.
Access is granted to the LAN behind via the SonicWALL appliance. You do not need a third party L2TP server solution.
How to configure your SonicWALL L2TP VPN server
Follow these easy steps in order:
1 - Login to your SonicWALL NSA UTM appliance as the Administrator in Configuration Mode.

2 - Navigate to Network and Address Objects
3 - Add the following Address Object:
Name: iPad L2TP Subnet (or another name you wish to identify with)
Zone Assignment: VPN
Type: Network
Network: 10.99.79.0 - This is the new network subnet that we will assign purely for L2TP connections. It shouldNOT be a subnet range in use on your network. You do not need to use this address, we have selected for display purposes.
Netmask: 255.255.255.0 - We have chosen to use a Class C subnet.

4 - Click OK to add the Address Object
5 - From the SonicWALL NSA menu select Users and Settings
6 - Ensure that Local Users are available. If you already have LDAP or RADIUS ensure that + Local Users is selected. This ensures you can use your Local User database on the SonicWALL (covered later).
7 - From the SonicWALL NSA menu navigate to VPN and L2TP Server.
8 - Enable the L2TP server and click on Configure. Set the details as follows:
Keep alive time (secs): 60
DNS Server 1: 192.168.168.1 (well, obviously use your internal DNS server)
DNS Server 2: 192.168.168.2 (again this is for display purposes - if you have a second DNS server, use it)
WINS Server 1: 0.0.0.0 (or enter your WINS IP address here)
WINS Server 2: 0.0.0.0 (as above)
Select Use the Local L2TP IP Pool
Start IP: 10.99.79.1 (this is the start IP of the L2TP network you created earlier)
End IP: 10.99.79.10 (this is the end IP of the L2TP network you created earlier)
User group for L2TP users: Trusted Users (or Everyone if you prefer)

9 - From the SonicWALL NSA menu, whilst still in VPN select Settings
10 - Configure the WAN GroupVPN policy with the following settings:
General Tab
Shared Secret: password (well, enter your password here)

Proposals Tab
IKE (Phase 1) Proposal
DH Group: Group 2
Encryption: 3DES
Authentication: SHA1
Life Time (seconds): 28800
Ipsec (Phase 2) Proposal
Protocol: ESP
Encryption: 3DES
Authentication: SHA1
Enable Perfect Forward Secrecy: Disabled
Life Time (seconds): 28800

Advanced Tab
Enable Windows Network (NetBIOS) Broadcast: Enabled
Enable Multicast: Disabled
Management via this SA: Unchecked for both HTTP and HTTPS
Default LAN Gateway: Public (WAN) IP address of the SonicWALL appliance
Require Authentication of VPN Clients via XAUTH: Enabled
User Group for XAUTH Users: Trusted Users (or Everyone)
Allow Unauthenticated VPN Client Access: Disabled

Client Tab
Cache XAUTH User Name and Password on Client: Always
Virtual Adapter settings: DHCP Lease
Allow Connections to: This Gateway Only
Set Default Route as this Gateway: Enabled
Apply VPN Access Control List: Disabled
Use Default Key for Simple Client Provisioning: Disabled

11 - Returning to the SonicWALL appliance menu, and still in VPN, select DHCP over VPN
12 - Select Central Gateway and click on Configure and ensure the following:
Use Internal DHCP Server: Enabled
For Global VPN Client: Enabled
For Remote Firewall: Disabled
Send DHCP requests to the server address listed below: Disabled
Relay IP Address (Optional): 0.0.0.0

13 - From the SonicWALL menu navigate to Firewall and Access rules
14 - Select VPN to WAN from the matrix or drop down menu and add the following rule:
Action: Allow
From Zone: VPN
To Zone: WAN
Service: ANY
Source: WAN RemoteAccess Networks
Destination: ANY
Users Allowed: All
Schedule: Always on

15 - From the SonicWALL menu navigate to Network and NAT Policies
16 - Add the following NAT Policy:
Original Source: iPad L2TP Subnet (or whatever you created in Step 3)
Translated Source: WAN Primary IP (usually X1 IP)
Original Destination: Any
Translated Destination: Original
Original Service: Any
Translated Service: Original
Inbound Interface: Any
Outbound Interface: X1 (your WAN interface)

17 - From the SonicWALL NSA menu navigate to Users and Local Users
18 - Create a new user (if one doesn't exist) and then select the VPN Access tab and add the following objects:
LAN Subnets
WAN RemoteAccess Networks
iPad L2TP Subnet (or whatever you called the Address Object that you created in step 3)
NOTE: You can add these networks to the Trusted Users or Everyone list if you wish - or individually for users. You must also add any other Address Objects to which you may require access here. We have used the basic LAN Subnets for access to the LAN above for demonstrative purposes.
19 - Click on OK to add the user