I have a web site with an admin subdirectory that is protected by integrated Windows authentication. Works flawlessly from remote PCs. But when I attempt to access these pages on the server itself, I get an authorization failure. I'm using the proper hostname, not localhost. Tried Chrome and IE, same result.
Any suggestions?
You are almost certainly running into the Windows loopback check that was introduced with IIS 5.1. This is a security feature to avoid certain types of reflection attacks against the system.
Microsoft has a KB article describing workarounds. They basically boil down to modifying the registry to either disable the loopback check, or to allow certain hostnames (e.g. your local host name or site name) to back-connect.
You can quickly disable the check via PowerShell:
New-ItemProperty HKLM:\System\CurrentControlSet\Control\Lsa -Name "DisableLoopbackCheck" -Value "1" -PropertyType dword
Below are Microsoft's official instructions. Note that although the below instructions indicate a reboot, I've found that IE usually picks up the change right away.
Method 1: Specify host names (Preferred method if NTLM authentication is desired)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0ENTER.IISAdmin service.Method 2: Disable the loopback check (less-recommended method)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\LsaENTER.Addendum:
To set the DisableStrictNameChecking registry entry to 1:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanServer\ParametersENTER.
Here are the PowerShell commandlets that I wrote to manage the loopback check settings. It includes code that attempts to get the hostnames for all IIS web sites that use Windows Authentication and sets the back connection host names.
Import-Module WebAdministration
function Add-BackConnectionHostName
{
<#
.SYNOPSIS
Adds the back connection hostnames that will bypass the server loopback check.
.DESCRIPTION
Adds the hostname to the list of back connection hostnames that will bypass the server loopback check. Back connection host names
can be used to address the problem with IIS sites using Windows Authentication that is described in Microsoft KB896861.
.EXAMPLE
Add-BackConnectionHostName mywebsite.mydomain.tld
.EXAMPLE
Add-BackConnectionHostName mywebsite1.mydomain.tld, mywebsite2.mydomain.tld
.PARAMETER Hostname
The Hostname to add to the back connection hostnames list.
.LINK
Remove-BackConnectionHostName
Get-BackConnectionHostName
Enable-ServerLoopbackCheck
Disable-ServerLoopbackCheck
Get-ServerLoopbackCheck
"You receive error 401.1 when you browse a Web site that uses Integrated Authentication and is hosted on IIS 5.1 or a later version" (http://support.microsoft.com/en-us/kb/896861)
#>
[CmdletBinding(SupportsShouldProcess = $true)]
param
(
[Parameter(ValueFromPipeline = $true, Mandatory = $true)]
[string] $Hostname
)
begin
{
$keyPath = "HKLM:\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0"
$propertyName = "BackConnectionHostNames"
$key = Get-Item $keyPath
$property = $null
$propertyValues = $null
if ($key -ne $null)
{
$property = Get-ItemProperty $keyPath -Name $propertyName -ErrorAction SilentlyContinue
if ($property -eq $null)
{
$property = New-ItemProperty $keyPath -Name $propertyName -Value $null -PropertyType ([Microsoft.Win32.RegistryValueKind]::MultiString) -ErrorAction Stop
Write-Verbose "Created the $($propertyName) property."
}
if ($property -ne $null)
{
$propertyValues = $property.$propertyName
}
}
}
process
{
if ($property -ne $null)
{
foreach ($hostNameValue in $Hostname)
{
if ([string]::IsNullOrWhiteSpace($hostName) -eq $false -and $propertyValues -notcontains $hostNameValue)
{
$propertyValues += $hostNameValue
Write-Verbose "Added $($hostName) to the back connection hostnames."
}
else
{
Write-Verbose "Back connection host names already has an entry for $($hostName)."
}
}
}
}
end
{
if ($propertyValues -ne $null)
{
$propertyValues = $propertyValues | ?{ [string]::IsNullOrWhiteSpace($_) -eq $false } | Sort -Unique
Set-ItemProperty $keyPath -Name $propertyName -Value $propertyValues
}
}
}
function Remove-BackConnectionHostName
{
<#
.SYNOPSIS
Removes the hostname from the list of back connection hostnames that will bypass the server loopback check.
.DESCRIPTION
Removes the hostname from the list of back connection hostnames that will bypass the server loopback check.
.EXAMPLE
Remove-BackConnectionHostName mywebsite.mydomain.tld
.EXAMPLE
Remove-BackConnectionHostName mywebsite1.mydomain.tld, mywebsite2.mydomain.tld
.PARAMETER Hostname
The Hostname to remove from the back connection hostnames list.
.LINK
Add-BackConnectionHostName
Get-BackConnectionHostName
Enable-ServerLoopbackCheck
Disable-ServerLoopbackCheck
Get-ServerLoopbackCheck
"You receive error 401.1 when you browse a Web site that uses Integrated Authentication and is hosted on IIS 5.1 or a later version" (http://support.microsoft.com/en-us/kb/896861)
#>
[CmdletBinding(SupportsShouldProcess = $true)]
param
(
[Parameter(ValueFromPipeline = $true, Mandatory = $true)]
[string] $Hostname
)
begin
{
$keyPath = "HKLM:\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0"
$propertyName = "BackConnectionHostNames"
$key = Get-Item $keyPath
$property = $null
$propertyValues = $null
if ($key -ne $null)
{
$property = Get-ItemProperty $keyPath -Name $propertyName -ErrorAction SilentlyContinue
if ($property -ne $null)
{
$propertyValues = $property.$propertyName
}
else
{
Write-Verbose "The $($propertyName) property was not found."
}
}
}
process
{
if ($property -ne $null)
{
foreach ($hostNameValue in $Hostname)
{
if ($propertyValues -contains $hostNameValue)
{
$propertyValues = $propertyValues | ? { $_ -ne $hostName }
Write-Verbose "Removed $($hostName) from the $($propertyName) property."
}
else
{
Write-Verbose "No entry for $($hostName) was found in the $($propertyName) property."
}
}
}
}
end
{
if ($property -ne $null)
{
$propertyValues = $propertyValues | ?{ [string]::IsNullOrWhiteSpace($_) -eq $false } | Sort -Unique
if ($propertyValues.Length -ne 0)
{
Set-ItemProperty $keyPath -Name $propertyName -Value $propertyValues
}
else
{
Remove-ItemProperty $keyPath -Name $propertyName
Write-Verbose "No entries remain after removing $($hostName). The $($propertyName) property was removed."
}
}
}
}
function Get-BackConnectionHostName
{
<#
.SYNOPSIS
Gets the list of back connection hostnames that will bypass the server loopback check.
.DESCRIPTION
Gets the back connection hostnames that will bypass the server loopback check. Back connection host names can be used to address
the problem with IIS sites using Windows Authentication that is described in Microsoft KB896861.
.EXAMPLE
Get-BackConnectionHostName
.LINK
Add-BackConnectionHostName
Remove-BackConnectionHostName
Enable-ServerLoopbackCheck
Disable-ServerLoopbackCheck
Get-ServerLoopbackCheck
"You receive error 401.1 when you browse a Web site that uses Integrated Authentication and is hosted on IIS 5.1 or a later version" (http://support.microsoft.com/en-us/kb/896861)
#>
[CmdletBinding(SupportsShouldProcess = $false)]
param
(
)
begin
{
$keyPath = "HKLM:\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0"
$propertyName = "BackConnectionHostNames"
$key = Get-Item $keyPath
$property = $null
if ($key -ne $null)
{
$property = Get-ItemProperty $keyPath -Name $propertyName -ErrorAction SilentlyContinue
if ($property -eq $null)
{
Write-Verbose "The $($propertyName) property was not found."
}
}
}
process
{
$propertyValues = $null
if ($property -ne $null)
{
$propertyValues = $property.$propertyName
}
return $propertyValues
}
end
{
}
}
function Enable-ServerLoopbackCheck
{
<#
.SYNOPSIS
Enables the server loopback check. Enabled is the normal state for a Windows Server.
.DESCRIPTION
Enables the server loopback check. Having the loopback check enabled is the normal state for a Windows Server. Disabling the loopback check can be used to address
the problem with IIS sites using Windows Authentication that is described in Microsoft KB896861. It is NOT the preferred method. See the KB article for more details.
.EXAMPLE
Enable-ServerLoopbackCheck
.LINK
Add-BackConnectionHostName
Remove-BackConnectionHostName
Get-BackConnectionHostName
Enable-ServerLoopbackCheck
Get-ServerLoopbackCheck
"You receive error 401.1 when you browse a Web site that uses Integrated Authentication and is hosted on IIS 5.1 or a later version" (http://support.microsoft.com/en-us/kb/896861)
#>
[CmdletBinding(SupportsShouldProcess = $true)]
param
(
)
begin
{
$keyPath = "HKLM:\SYSTEM\CurrentControlSet\Control\Lsa"
$propertyName = "DisableLoopbackCheck"
$key = Get-Item $keyPath
$property = $null
if ($key -ne $null)
{
$property = Get-ItemProperty $keyPath -Name $propertyName -ErrorAction SilentlyContinue
if ($property -eq $null)
{
Write-Verbose "The $($propertyName) property was not found."
}
}
}
process
{
if ($property -ne $null)
{
Set-ItemProperty $keyPath -Name $propertyName -Value 0
}
}
end
{
}
}
function Disable-ServerLoopbackCheck
{
<#
.SYNOPSIS
Disables the server loopback check for all hostnames. Enabled is the normal state for a Windows Server.
.DESCRIPTION
Disables the server loopback check for all hostnames. Having the loopback check enabled is the normal state for a Windows Server. Disabling the loopback check can be used
to address the problem with IIS sites using Windows Authentication that is described in Microsoft KB896861. It is NOT the preferred method. See the KB article for more details.
.EXAMPLE
Disable-ServerLoopbackCheck
.LINK
Add-BackConnectionHostName
Remove-BackConnectionHostName
Get-BackConnectionHostName
Enable-ServerLoopbackCheck
Get-ServerLoopbackCheck
"You receive error 401.1 when you browse a Web site that uses Integrated Authentication and is hosted on IIS 5.1 or a later version" (http://support.microsoft.com/en-us/kb/896861)
#>
[CmdletBinding(SupportsShouldProcess = $true)]
param
(
)
begin
{
$keyPath = "HKLM:\SYSTEM\CurrentControlSet\Control\Lsa"
$propertyName = "DisableLoopbackCheck"
$key = Get-Item $keyPath
$property = $null
if ($key -ne $null)
{
$property = Get-ItemProperty $keyPath -Name $propertyName -ErrorAction SilentlyContinue
if ($property -eq $null)
{
Write-Verbose "The $($propertyName) property was not found."
}
}
}
process
{
if ($property -ne $null)
{
Set-ItemProperty $keyPath -Name $propertyName -Value 1
}
else
{
$property = New-ItemProperty $keyPath -Name $propertyName -PropertyType ([Microsoft.Win32.RegistryValueKind]::DWord) -Value 1
}
}
end
{
}
}
function Get-ServerLoopbackCheck
{
<#
.SYNOPSIS
Gets the status of the server loopback check. Enabled is the normal state for a Windows Server.
.DESCRIPTION
Gets the status of the server loopback check. Having the loopback check enabled is the normal state for a Windows Server. Disabling the loopback check can be used
to address the problem with IIS sites using Windows Authentication that is described in Microsoft KB896861. It is NOT the preferred method. See the KB article for
more details.
.EXAMPLE
Get-ServerLoopbackCheck
.LINK
Add-BackConnectionHostName
Remove-BackConnectionHostName
Get-BackConnectionHostName
Enable-ServerLoopbackCheck
Disable-ServerLoopbackCheck
"You receive error 401.1 when you browse a Web site that uses Integrated Authentication and is hosted on IIS 5.1 or a later version" (http://support.microsoft.com/en-us/kb/896861)
#>
[CmdletBinding(SupportsShouldProcess = $false)]
param
(
)
begin
{
$keyPath = "HKLM:\SYSTEM\CurrentControlSet\Control\Lsa"
$propertyName = "DisableLoopbackCheck"
$key = Get-Item $keyPath
$property = $null
if ($key -ne $null)
{
$property = Get-ItemProperty $keyPath -Name $propertyName -ErrorAction SilentlyContinue
}
}
process
{
$loopbackCheckStatus = "Enabled"
if ($property -ne $null)
{
switch ($property)
{
0 { $loopbackCheckStatus = "Enabled" }
1 { $loopbackCheckStatus = "Disabled" }
default { $loopbackCheckStatus = "Unknown" }
}
}
return $loopbackCheckStatus
}
end
{
}
}
function Get-WebsiteHostname
{
<#
.SYNOPSIS
Gets the hostnames for the IP addresses bound to a web site.
.DESCRIPTION
Gets the hostnames for the IP addresses bound to a web site. Where a host header exists, the host header is used; otherwise, the IP address is looked up
in DNS to see if a PTR record exists.
.EXAMPLE
Get-WebSiteHostname $webSite
.EXAMPLE
Get-WebSiteHostname -Name 'Default Web Site'
.EXAMPLE
Get-Website | Get-WebSiteHostname
.LINK
Get-Website
#>
[CmdletBinding(SupportsShouldProcess = $false)]
param
(
[Parameter(ValueFromPipeline = $true, ValueFromPipelineByPropertyName = $true, Mandatory = $true)]
[string] $Name
)
process
{
$siteHostnames = @()
foreach ($webSiteName in $Name)
{
$bindings = Get-WebBinding -Name $Name
foreach ($binding in $bindings)
{
$bindingInfo = $binding.bindingInformation.Split(':')
$hostHeader = $bindingInfo[2]
$bindingInfoAddress = $null
$isValidIP = [System.Net.IPAddress]::TryParse($bindingInfo[0], [ref] $bindingInfoAddress)
$siteHostname = $null
if ($bindingInfo -eq '*')
{
Write-Warning "The $($webSiteName) web site has a binding address set to All Unassigned."
}
elseif ([string]::IsNullOrWhiteSpace($hostHeader) -eq $false)
{
$siteHostname = $hostHeader
Write-Verbose "The $($webSiteName) web site has a host header set to $($siteHostname)."
}
elseif ($isValidIP -eq $true)
{
$siteHostname = (Resolve-DnsName $bindingInfoAddress -DnsOnly PTR -ErrorAction SilentlyContinue).NameHost
if ($siteHostname -ne $null)
{
Write-Verbose "The $($webSiteName) web site has an IP Address $($bindingInfoAddress) that resolves to $($siteHostname)."
}
else
{
Write-Warning "The $($webSiteName) web site has an IP Address $($bindingInfoAddress) with no PTR record."
}
}
}
if ($siteHostname -ne $null)
{
$siteHostnames += $siteHostname
}
}
return $siteHostnames | Sort -Unique
}
}
# Use the IIS administration commandlets and the ones above to do the
# following:
# 1. Get all the IIS web sites that use Windows authentication.
# 2. Get the hostnames from either the host header setting or the
# DNS reverse lookup of the hostnames from the IP address.
# 3. Add the hostnames to the BackConnectionHostNames registry key.
# 4. Display the contents of the BackConnectionHostNames registry key.
$windowsAuthenticatedWebSites = Get-Website | ?{ (Get-WebConfiguration -Filter '/system.web/authentication' -PSPath $_.PSPath).mode -eq 'Windows' }
$webSiteHostnames = $windowsAuthenticatedWebSites | Get-WebsiteHostname
$webSiteHostNames | Add-BackConnectionHostName
Get-BackConnectionHostName
