When the LanGuard server is scanning the target Windows machine or tries to deploy an agent or patch remotely, there are issues with connectivity to hosts on the network, and the following error can be found: The RPC server is unavailable. The error might be displayed directly in the console or located in the debug logs when triaging the problems.
The error usually occurs when LanGuard is performing WMI checks, connecting to the remote registry, or to the administrative share of a remote machine. It means that the remote computer is not reachable through Remote Procedure Calls (RPC). To resolve this issue:
- Ensure that the Required Settings to Scan a Machine and Successfully Install Missing Patches Using GFI LanGuard are met.
- Verify all the Required Network Connectivity and Security Permissions for GFI LanGuard Operations and address the failing checks:
- Resolve DNS issues with the domain and network administrators.
- If the target computer firewall allows inbound requests for the required ports, but the checks from the server hosting the LanGuard are failing (even direct checks with telnet or similar tool), it means that something in your network environment is blocking the traffic, resolve this with the network administrator.
- Check all the policies for NTLM in the local policy editor (gpedit.msc) AND in the local security policy editor (secpol.msc) under the Computer Configuration > Windows Settings > Security Settings > Local Policies > Security Options section and set them to Not defined or Allow All (Important Note: the same policies can be set separately in each editor and the most restrictive will take effect)
Retry the failing operation. If the error is still there, Troubleshoot WMI. You may need to enable WMI on the target machine via Windows Firewall > Inbound Rules > Windows Management Instrumentation (WMI-In).
RPC uses port 135 and can be used over SMB protocol over ports 139 and/or 445 (for example, when connecting to the administrative shares or the remote registry). RPC can also use dynamic ports from a large port range by default (1024 - 65535 for Microsoft Windows 2003 and XP / 49152 - 65535 for Microsoft Windows Server 2012, Windows 8, Windows Server 2008 R2, Windows 7, Windows Server 2008, and Windows Vista). The port range used can be limited:
Repeat the scan or agent deployment operation. If the issue persists, contact GFI LanGuard Support.