After getting a response from SagePay I have found the following important notes:
- You can use Form/Server/Direct integration interchangeably on the same vendor's account, without needing to change settings or register anything
- The 4020 error genuinely is an IP restriction error and is not masquerading another error
The issue here was that the IP address of the web server (www.mysite.com), being on a VPS, turned out to not be the same address as the one used when curl
requests were made. I made a test PHP page that mailed the IP in $_SERVER['REMOTE_ADDR']
to myself and put it on another server. I then used curl
to grab that script and low and behold it was a different IP. Putting (a zero padded version of) this in to the Valid IPs
section in My SagePay control panel (logged in with the admin account) it sprung to life immediately.
Update
You can use:
curl icanhazip.com
Like so:
[user@host ~]# curl icanhazip.com
177.12.41.200
to display the correct IP to use, from the command line of the server you're hosting the web site on, instead of uploading files and all that malarkey. More information and usage here.