I'm setting up Internet Secure, which is very similar to Authorize.net
I'm using Virtuemart 1.1, but the only instructions I could find where for Virtuemart 1.0:
https://forum.virtuemart.net/index.php?topic=8222.msg186532If you are in this situation, here's what I did:
around line 381, it should read
$host = "secure.internetsecure.com";
$result = vmConnector::handleCommunication( "https://secure.internetsecure.com:443/process.cgi", $poststring );
around line 590, it should read the same thing
$host = "secure.internetsecure.com";
$result = vmConnector::handleCommunication( "https://secure.internetsecure.com:443/process.cgi", $poststring );
Hope that helps!