How to add more than one machine to the trusted hosts list using winrm
I prefer to work with the PSDrive WSMan:\.
Get TrustedHosts
Get-Item WSMan:\localhost\Client\TrustedHostsSet TrustedHosts
provide a single, comma-separated, string of computer names
Set-Item WSMan:\localhost\Client\TrustedHosts -Value 'machineA,machineB'or (dangerous) a wild-card
Set-Item WSMan:\localhost\Client\TrustedHosts -Value '*'to append to the list, the -Concatenate parameter can be used
Set-Item WSMan:\localhost\Client\TrustedHosts -Value 'machineC' -Concatenate
The suggested answer by Loïc MICHEL blindly writes a new value to the TrustedHosts entry.
I believe, a better way would be to first query TrustedHosts.
As Jeffery Hicks posted in 2010, first query the TrustedHosts entry:
PS C:\> $current=(get-item WSMan:\localhost\Client\TrustedHosts).valuePS C:\> $current+=",testdsk23,alpha123"PS C:\> set-item WSMan:\localhost\Client\TrustedHosts –value $current