I wrote a Powershell script where I update hosts file at runtime: add entries, clear entries.
An example of what I am doing:
Import-Module 'Carbon'
#Carbon module functions
Reset-HostsFile
#No exception expected
$result = Invoke-Webrequest -Uri "https://blogs.technet.microsoft.com" -UseBasicParsing
$result = $null
#No exception expected
$result = Invoke-Webrequest -Uri "https://www.google.fr" -UseBasicParsing
$result = $null
#No exception expected
$result = Invoke-Webrequest -Uri "http://www.lequipe.fr" -UseBasicParsing
$result = $null
#Block google.fr
Set-HostsEntry -IPAddress 0.0.0.0 -HostName 'google.fr www.google.fr' -Description "Google"
#No exception expected
$result = Invoke-Webrequest -Uri "https://blogs.technet.microsoft.com" -UseBasicParsing
$result = $null
#No exception expected
$result = Invoke-Webrequest -Uri "https://www.google.fr" -UseBasicParsing
$result = $null
#Exception expected
$result = Invoke-Webrequest -Uri "http://www.lequipe.fr" -UseBasicParsing
$result = $null
#Block lequipe.fr
Set-HostsEntry -IPAddress 0.0.0.0 -HostName 'lequipe.fr www.lequipe.fr' -Description "Google"
#No exception expected
$result = Invoke-Webrequest -Uri "https://blogs.technet.microsoft.com" -UseBasicParsing
$result = $null
#No exception expected
$result = Invoke-Webrequest -Uri "https://www.google.fr" -UseBasicParsing
$result = $null
#Exception expected
$result = Invoke-Webrequest -Uri "http://www.lequipe.fr" -UseBasicParsing
$result = $null
Reset-HostsFile
#No exception expected
$result = Invoke-Webrequest -Uri "https://blogs.technet.microsoft.com" -UseBasicParsing
$result = $null
#No exception expected
$result = Invoke-Webrequest -Uri "https://www.google.fr" -UseBasicParsing
$result = $null
#No exception expected
$result = Invoke-Webrequest -Uri "http://www.lequipe.fr" -UseBasicParsing
$result = $null
When an exception is expected, no exception is thrown. This is because I am still running in the same Powershell environment. If I open a new shell to call Invoke-Webrequest with the uri blocked, an exception is thrown.
Carbon module can be found at this address : http://get-carbon.org/ There is nothing particular with the functions used. Before using Carbon, I was updating hosts file using Powershell cmdlet Clear-Content and Add-Content. The issue was already present.
A solution that I have implemented is to create a Job using the following peace of code:
$job = Start-Job –Scriptblock { Invoke-Webrequest -Uri "https://www.google.fr" -UseBasicParsing }
Wait-Job $job
Receive-Job $job -OutVariable result
$result
But this solution is not clean, it creates a background worker.
Is there any way to "refresh" powershell environment without closing/opening powershell. I tried:
- ipconfig /flushdns
- arp -a
- netsh interface ip delete arpcache
At the end, the code will run using a Windows Scheduled Task.
Thank you for your support. Vinc3nt
