Troubleshooting ELM Console Communications

The ELM Console communicates with the Session Manager component of the ELM Server process. This communication is completely DCOM-based. DCOM and RPC connections are made between the ELM Server and the ELM Console to facilitate the transfer of data.

If you are not able to connect to an ELM Server from an ELM Console, or if you are able to connect but not receive any information, check the following to see if there is a configuration problem.

• Do you still have IP connectivity and good name resolution between the ELM Server and the ELM Console? IP connectivity and healthy name resolution are essential for ELM to operate properly.
  
• Are DCOM ports been blocked through a firewall, packet filtering or some other mechanism? Because all communication between an ELM Server and an ELM Console are DCOM calls that occur via RPC, TCP and UDP port 135 (RPC Endpoint Mapper port) must be open between the Server and the Console. In addition, DCOM also uses RPC dynamic port allocation. By default, RPC dynamic port allocation randomly selects port numbers above 1024. You can control which ports RPC dynamically allocates for incoming communication and then configure your firewall to confine incoming external communication to only those ports (and TCP/UDP port 135). For more information on DCOM and firewalls, check out Microsoft's White Paper on Using DCOM with Firewalls. MSDN users can find this article here.
  
  
  On each end, run netstat -a at a command prompt and verify that each side is listening on TCP/UDP port 135. You should see them listed like the following:
  
  TCP server:epmap server:0 LISTENING
  UDP server:epmap *:*

where server is the name of your ELM Server or ELM Console, depending on which computer you are running netstat.

• Do the proper accounts have DCOM Allow Access and Allow Launch permissions? Both the ELM Server service account and the account of the user running the ELM Console need DCOM Allow Access and DCOM Allow Launch permissions on the computer where the ELM Console is running. In addition, all ELM Console users require DCOM Allow Launch permissions on the ELM Server computer. During installation, the setup process automatically grants the Everyone group Allow Access permissions in DCOM. These permissions can be viewed and edited via the DCOM Configuration Utility (DCOMCNFG.exe). Follow the instructions below that correspond with your ELM Server and ELM Console platforms.
  
  Ø In Windows NT or Windows 2000:
  
  1. Launch DCOMCNFG.EXE.
  2. Navigate to the Default Security tab.
  3. Default Access Permissions, click the Edit Default button.
  4. Verify that Everyone has Allow Access. Alternatively, you can revoke Allow Access for Everyone and
  grant your account and the ELM Server service account Allow Access rights.
  5. Close DCOMCNFG.EXE.
  
  
  Ø In Windows XP and Windows 2003:
  
  1. Launch DCOMCNFG.EXE or the Component Services snap-in.
  2. Expand Component Services, then expand Computers so that My Computer is visible.
  3. Right-click on My Computer and select Properties.
  4. Navigate to the Default COM Security tab.
  5. In the Access Permission area, click the Edit Default button.
  6. Verify that Everyone has Allow Access. Alternatively, you can revoke Allow Access for Everyone and
  grant your account and the ELM Server service account Allow Access rights.
  7. Close DCOMCNFG.EXE.
  
  You may need to reboot for the DCOM security changes to take effect.
  
• Is the ELM Server running on NT Workstation, Windows 2000 Professional or Windows XP? These operating systems have a hard-coded limit of 10 inbound TCP/IP connections. Once there are 10 established connections, no new connections will be able to be established until one or more connections is freed up. You can use the netstat command to count the number of TCP/IP connections in use. The resolution is to upgrade to a Windows Server family product.

If none of these solutions resolves your issue, please contact TNT Software's Product Support Group for assistance.