I'm using a SonicWall TZ 100 with a basic configuration of X0 for the LAN and X1 for the WAN. The WAN uses DHCP to obtain its routable IP address. I want to obtain a second routable IP from my ISP. I'm in luck because my cable company will provide me with an additional dynamic IP for $5/mo. How do I bind this IP to my SonicWall?

My additional dynamic IP will not be consecutive to the original one. It won't even be on the same class C. I think what I want to do is to use one of the empty ports/interfaces (X2, X3, or X4), tell that interface to use DHCP, and then add that interface to the WAN "zone". I can't figure out how to do this though. Here's what I've tried so far:

(1) I've looked in Network >> Interfaces. I see X0 and X1 but the other unused interfaces don't show up. I don't see an "Add" button to add the new interfaces.

(2) I've looked in Network >> Zones. I see that X0, X2, X3, X4 are in the LAN zone. I tried to drag X3 into the WAN zone but I can't. Nor does clicking the "Configure" button allow me to move an unused interface from LAN to WAN.

(3) I've read the post entitled Splitting up multiple WAN's on Sonicwall. This doesn't seem applicable to me.

Any thoughts?

  • The S****wall TZ100 series definitely does support multiple WAN interfaces.
    – Skyhawk
    Oct 11, 2012 at 17:59
  • I think I initially misread your response. So it DOES support multiple WANs? That's good news. I thought so. I'm sure there's an easy solution. I have a parallel post at SonicWall. Will let you know if I get an answer there. Oct 11, 2012 at 18:21
  • Are you running the "Enhanced" version of SonicOS? You cannot change an interface's zone from LAN to WAN in the "Standard" version.
    – Skyhawk
    Oct 11, 2012 at 20:22
  • I am running SonicOS Enhanced I was able to get the X4 interface shifted over to the WAN zone. I was also able tell it to use DHCP. It doesn't want to pick up an address though. Log says, "Retransmitting DHCP DISCOVER"... but no response from DHCP server. Oct 11, 2012 at 21:04

3 Answers 3


On the Network>Interfaces page, click on the "Show Portshield Interfaces" button on the top right of the Interface table. That will show you the other interfaces.

Then edit X2, change it to the WAN zone and set the IP assignment to DHCP.


I cannot imagine why on Earth you would want to have two dynamic IP addresses from the same ISP, but here is how to implement your highly unusual scheme:

  1. Install a switch (one not used for any other purpose) between the firewall and your ISP router.

  2. Plug two of the firewall's WAN interfaces into the switch.

  3. Configure both WAN interfaces to use DHCP.

  • 1
    #1 and #2 have already been done. My question was about how to do #3. Your snide comment is unappreciated. Did it ever occur to you that ISPs offer multiple DHCP addresses to customers for a reason? It's a very popular add-on service. Having multiple DHCP addresses is very common for home users who want to expose multiple services that both must use the same port (e.g. 443) and don't want the added expense of a static IP. You really need to relax. Oct 11, 2012 at 18:11
  • ServerFault is intended for questions relating to professional network and systems administration, not "home user" scenarios. Professional sysadmins do not "expose services" on dynamic IPs.
    – Skyhawk
    Oct 11, 2012 at 20:18

Unfortunately I don't have a similar appliance to work with, so I can't give exact instructions. What you should be looking for is bridge/transparent mode.

The feature is discussed on page 187 of product guide.

I assume, based on the manual, that you should choose (in interface configuration) LAN/DMZ zone, and transparent/bridged mode for IP assignment. And possibly WAN as primary bridge interface.

Would this help?

  • Thanks for the reference. The documentation you linked to says that transparent mode is for "spanning a single IP subnet across two or more interfaces." But is this what I want? I'd be dealing with multiple IP subnets, no? They might give me an IP of for one interface and on another. Oct 11, 2012 at 18:15
  • Yes, you're right, L2 bridging would be more applicable of the two choices.
    – por
    Oct 11, 2012 at 18:36

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