Set up on Authorize.net Website
While registering with Authorize.net, please make sure that your account can work with both AIM (advanced integration method) and ARB (automated recurring billing).
You must setup the this silent post url in your authorize.net account: http://linkdomain/signup/process_authorizearb.php
Replace in the above example linkdomain with your Link Domain. You also must setup your MD5 Hash value in your authorize.net account. Please ask authorize.net support for help with this.
Set up Authorize in NATS
When prompted, enter the Merchant Login ID, Transaction Key, and MD5 Hash Value that were provided to you by Authorize.net under the "Account Info" section. If you were not provided with this information, please contact your biller to receive it.
Next, go to the Sites Admin, create or edit a tour, and scroll down to the "Join Options for this Tour" section and click the "Edit Option Details" for this tour" icon that corresponds to the join option you want to use.
In the "Biller Codes" section on the next page, locate your Authorize.net Order Description and Amount of Time (in seconds) that authorize.net will use for finding duplicate transactions (these steps are optional).
NATS is able to verify that the postback for a rebill indeed came from authorize.net using the MD5 hash value. Unfortunately this verification is not possible for credit and void transactions. If you would like NATS to process credit and void transactions, please go configuration -> billers in your NATS admin and turn on the PROCESS_AUTHORIZEARB_CREDIT_VOID option. Please note that once you do this, anyone will be able to post credits and voids for authorize.net transactions.
Authorize.net is not able to send the reference transaction id for credit transactions to NATS (the transaction id of the transaction being credited). When entering credits in authorize.net admin please make sure to specify the transaction id being credited and nothing else in the description field for the credit transaction. Otherwise NATS will not be able to process authorize.net credits. This is not an issue for void transactions.
Authorize.net does not import chargeback transactions from banks. Because of it NATS is not able to process chargebacks resulting from authorize.net transactions.