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tfc2017
Engaged Sweeper
Hello,

during an IP range scan, we discovered that almost all the user machines cannot be scanned.

Servers and VMs all work without an issue, but maybe 95% of the user machines are displaying connection problems.

All of the machines are showing this error in the connection tester.

Scanning WMI..
The RPC server is unavailable.

The RPC server is unavailable.

The RPC server is unavailable.

Checking \\--------------\Admin$ Access
Connection: FAILURE. Error: The network path was not found

The RPC server is unavailable.

The RPC server is unavailable.
.
.
.

Could not edit Registry to scan Kerberos errors

Done.


There are a handful of machines for which the network scan worked successfully and there are no RPC error messages. These machines are using the same firewall policy and AV as the others.

Does Remote RPC have to be enabled on each machine for this to work? Is there another change I need to make on the server?

I look forward to any response, thank you!!!


Regards.
1 ACCEPTED SOLUTION
Bruce_B
Lansweeper Alumni
In most cases, firewall issues are to blame for RPC errors. Lansweeper pulls most Windows computer data from WMI (Windows Management Instrumentation), a management framework built into Windows operating systems. WMI data is, by default, sent over random ports. You indicate that firewalls and anti-virus software are disabled, but the first thing we would recommend is double-checking whether anything is blocking WMI traffic. The ports used by Lansweeper can be found in this article.

Other things you can try:
  • Running this script on the client machine. It will reconfigure DCOM and some other settings. DCOM is used to establish the initial connection to the client machine and could also cause RPC errors.
  • The troubleshooting steps in this knowledge base article. The article mentions some other possible causes of RPC errors.
  • In rare cases RPC errors can also be caused by credentials. Ensure that the credential used has full local administrator rights on the target computer, and AD read rights.

View solution in original post

5 REPLIES 5
Bruce_B
Lansweeper Alumni
In most cases, firewall issues are to blame for RPC errors. Lansweeper pulls most Windows computer data from WMI (Windows Management Instrumentation), a management framework built into Windows operating systems. WMI data is, by default, sent over random ports. You indicate that firewalls and anti-virus software are disabled, but the first thing we would recommend is double-checking whether anything is blocking WMI traffic. The ports used by Lansweeper can be found in this article.

Other things you can try:
  • Running this script on the client machine. It will reconfigure DCOM and some other settings. DCOM is used to establish the initial connection to the client machine and could also cause RPC errors.
  • The troubleshooting steps in this knowledge base article. The article mentions some other possible causes of RPC errors.
  • In rare cases RPC errors can also be caused by credentials. Ensure that the credential used has full local administrator rights on the target computer, and AD read rights.
Mister_Nobody
Honored Sweeper II
http://www.lansweeper.com/kb/6/firewall.html
tfc2017
Engaged Sweeper
Thanks for the quick reply!

File and Printer sharing is enabled for everyone by default.

I have gone through the article several times and verified port 135 is open. We use Symantec for the AV and firewall. I followed the steps in here to configure the firewall rule:

http://www.lansweeper.com/kb/203/configuring-symantec-endpoint-protection-for-use-with-lansweeper.html

I went as far to disable the SEP Firewall, re-enable the Windows firewall and open 135 there to see if it would make a difference.

Are there other settings local to the PC that need to be enabled? What about RPC?
Mister_Nobody
Honored Sweeper II
Also you can read KB
http://www.lansweeper.com/kb/2/The-RPC-server-is-unavailable.html
Mister_Nobody
Honored Sweeper II
Is File and Printer Sharing for Microsoft Networks checked?
http://www.home-network-help.com/simple-file-sharing.html