Archive

Posts Tagged ‘SSL/TLS’

vRealize Automation DEM worker cannot connect to Orchestrator

08/23/2016 Comments off

In vRA 6.2, using vRO 6.0, you may find that the data collection and other vRO workflows fail with the error “You must have at least one properly configured vCenter Orchestrator endpoint that is reachable”.  The IaaS/Monitoring/Log will show which DEM worker threw the error.  When you check the DEM worker logs for that instance, if you find the message “Could not create SSL/TLS secure channel. —> System.Net.WebException: The request was aborted: Could not create SSL/TLS secure channel“, you have probably been affected by VMKB 2123455 and MS KB 3061588.

Although both articles seem to suggest that removing the offending patch will solve the problem, I think figuring out exactly which patch is rather awkward.  The easier fix is to apply a quick registry hack to your DEM workers (and wherever the vRA Designer runs).

  1. Logon as an account with admin rights (suggest the account your IaaS services run under)
  2. locate or add the key

    HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\
    KeyExchangeAlgorithms\Diffie-Hellman

  3. Add/update the DWORD value ClientMinKeyBitLength and set the value to 512 decimal (200 hex)
  4. Restart the DEM worker service

 

Notes:
The Microsoft patch sets the default minimum group size to 1024.  It appears that the vRO 6.0.x appliances use something less than that.  This registry hack indicates that SCHANNEL should accept keys as small as 512 bits.  I suggest only applying this to the necessary and affected machines since it does lower the bar for the DHE security requirements.

Thanks to Zach Milleson for reminding me that this workaround may not resolve everyone’s issue, depending on which MS patches are installed.  If this workaround doesn’t work for you, you may have to locate and remove the offending patch.  YMMV.

Advertisements