Information
Set a timeout to limit how long the ESXi Shell and SSH services are allowed to run.
When the ESXi Shell or SSH services are enabled on a host they will run indefinitely. To avoid having these services left running set the ESXiShellTimeOut. The ESXiShellTimeOut defines a window of time after which the ESXi Shell and SSH services will automatically be terminated.
http://pubs.vmware.com/vsphere-60/topic/com.vmware.vsphere.security.doc/GUID-94F0C54F-05E3-4E16-8027-0280B9ED1009.html
http://pubs.vmware.com/vsphere-60/topic/com.vmware.vsphere.security.doc/GUID-B314F79B-2BDD-4D68-8096-F009B87ACB33.html
http://kb.vmware.com/kb/2004746
Solution
# Set Remove UserVars.ESXiShellTimeOut to 900 on all hosts -
Get-VMHost | Foreach { Set-VMHostAdvancedConfiguration -VMHost $_ -Name UserVars.ESXiShellTimeOut -Value 900 }