Sonicwall Wan Failover

I am using an NSA 2400 and have WAN Failover setup with a secondary ISP.  I have an Exchange server behind this firewall and need to know if I need NAT Policies for Exchange for the WAN Failover interface as well as access rules.  What is the best way to set this up?  Thanks!

cbsykesAsked:
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ccomleyCommented:
Only if your exchange server is visible from the outside.  If you have external users who do Outlook Web Access, and/or if your inbound email is delivered by SMTP then you need a public mapping.

And if you want inbound access via EITHER wan link, you need to create a nat mapping for both. And then it's a good idea to have a DNS entry for both.

Here's an example

mail1.mydomain.com is IP1 - where IP1 is in the WAN IP range from ISP1, and you create a NAT mapping for that to the internal IP of the ES box.  (I presume you already have this!)
mail2.mydomain.com is IP2 -  where IP2 is in the WAN Ip range for ISP2, and you create a NAT mapping for THAT to the ES box too.

You set your MX records up thus:-

In MX 10 mail1
In MX 20 mail2
in MX 30 relayhost.yourisp.com

Now, are you using pure fail-over or are you using load balancing?

If you're using failover, all taht remains is to ensure that your outbound mail works via the second WAN - which is easy if you are doing direct delivery, if you are using an ISP-owned smarthost, you will need to make sure that that will allow you to send from your secondary IP address.

If you are using load balancing, you will also need to make sure that any smarthost will accept your mail via either IP address. You can use a policy route to force the mail via WAN1  if/when Wan1 is available.

The only thing you can't fully automate is - which address external users use to try to fetch their mail via POP, IMAP or OWA - they will have to be told to use mail1, but if that's unavailable, they should try mail2.



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