Install and Use the OpenSRS Domains Pro Module for WHMCS

WHMCS (Web Host Manager Complete Solution) is a third-party billing and automation platform used by hosting resellers. The OpenSRS Domains Pro module (Opensrspro) is the OpenSRS-built registrar module for WHMCS, offering deeper feature coverage than the WHMCS-built OpenSRS module. This guide walks you through downloading, installing, and configuring it end-to-end.

About the Domains Pro module

The Opensrspro module installs alongside the WHMCS-developed OpenSRS module, so after installation you will see both entries in Setup > Products/Services > Domain Registrars. Once Opensrspro is activated and configured with your reseller API credentials, it handles domain provisioning, management, and reporting for any domain you assign to it.

Before you begin

• You have administrator access to your WHMCS instance and SSH/file access to the WHMCS server.
• You have an active OpenSRS reseller account at manage.opensrs.com.
• You can edit your server's firewall rules to allow outbound traffic on TCP ports 55000 and 55443.
• You know your server's outbound IP address. On shared hosting, this is often different from your server's primary IP — ask your hosting provider.

Step 1: Download the Opensrspro WHMCS module

Download the latest version of the module from the OpenSRS integrations page: opensrs.com/integration/tools/whmcs.

Step 2: Extract and upload to your WHMCS application

Extract the archive and upload its contents to your WHMCS application, preserving the folder structure. The WHMCS folder inside the module package maps to your base WHMCS directory on the server.

If you have modified your english.php file

Append the contents of append_to_lang.txt (located in WHMCS/lang/ inside the module package) to your existing english.php file.

If you have modified your additionaldomainfields.php file

Copy the additional lines from /includes/append_to_additionaldomainfields.php into your existing additionaldomainfields.php.

Step 3: Activate the module in WHMCS

Log in to your WHMCS admin interface and go to Setup > Products/Services > Domain Registrars. Locate OpenSRS Pro in the list and activate it.

Step 4: Generate your OpenSRS API key

The module authenticates to OpenSRS using an API key tied to your reseller account.

1. Log in to your reseller account at manage.opensrs.com.
2. Hover over the gear icon in the top-right corner and choose Account Settings.
3. Click the API Settings tab.
4. Copy the API key shown on the API Settings tab. You'll paste it into WHMCS in Step 6.

Step 5: Whitelist your server's outbound IP

OpenSRS only accepts API calls from IP addresses you've explicitly whitelisted.

1. On the API Settings tab, find IP Access Rules and click Edit.
2. Enter your server's outbound IP address and submit the change.
3. To whitelist a range, use CIDR notation and select the appropriate prefix from the drop-down.

Step 6: Configure your server and firewall

Your server and firewall must allow outbound TCP connections on ports 55000 and 55443 to the OpenSRS API endpoints:

• Production:rr-n1-tor.opensrs.net
• Test:horizon.opensrs.net

Step 7: Verify the server connection

From your server's command line, run:

telnet rr-n1-tor.opensrs.net 55000

You'll get one of three responses:

• Connection timed out — Port 55000 is not open on your server or firewall. Open it and retry.
• 0.9 XCP Connection refused: invalid ip address [XXX.XXX.XXX.XXX] REPLY 555 — The IP shown in the response is not yet whitelisted. Add it to your reseller account's IP Access Rules and wait up to one hour before retrying.
• 0.9 XCP VERSION CHECK XML:0.1 OpenSRS SERVER ready — Your connection is working correctly.

Step 8: Configure the Opensrspro module in WHMCS

Back in WHMCS, go to Setup > Products/Services > Domain Registrars and click Configure next to Opensrspro. Fill in the fields:

• TestUsername — Your reseller username for the OpenSRS test environment.
• TestAPIKey — Your test environment API key (different from your live key).
• ProdUsername — Your reseller username for the production environment.
• ProdAPIKey — Your production environment API key (the one copied in Step 4).
• Hashkey — Optional.
• TestMode — Enable to route calls to the test environment.

The remaining options are optional and can be enabled as needed:

• ForceForwardingIP
• ChangeLockedDomains
• LockTechContact
• GeneralError
• DisableTemplateChanges

Next steps

• Test a domain operation — With TestMode enabled, run a domain lookup or test registration to confirm the module is wired up correctly.
• Switch to production — Once tests pass, disable TestMode and re-run a low-risk operation against your live reseller account.
• If anything fails, see the troubleshooting guide — Common authentication, connection, and logging issues are covered in Troubleshoot Your WHMCS Module.
• Enable Module Logs — Turn on logging at Utilities > Logs > Module Logs so you can review request and response payloads when investigating issues.

Questions? Contact OpenSRS Support.