SharePoint and WebDAV–part 2

So I was troubleshooting mapping SharePoint though WebDAV and found I had to open the SharePoint site though office in one way or the other, in order to successfully map it. That was true, but for one very specific reason.

Talking about cookies, you need to know there is 2 kinds of cookies. Session Cookies and Persistent cookies. Session cookies only “lives” as long as your browser is open. As soon as you close *ALL* your browser windows they cookie will expire. Persistent cookies will stay on your machine until the expire date on the cookie is hit.

When you setup SharePoint to use Claimsbased authentication SharePoint save a cookie on your machine called the “FedAuth” cookie. This is your what authenticate you every time you hit SharePoint. It gets set when the Identity Provider (STS/ADFS) makes your browser “post” your claims to https://fqdn/_trust/ .It gets removed when you click “sign out” or “Sign in as Different User”.

The WebDAV client, and various Office applications does support working with websites that facilitate Claimsbased authentication, but they cannot authenticate you. It assumes you have a FedAuth cookie on your machine. Some times you will get a browser popup, but there are places this wont happen (like with WebDAV). I had told SharePoint to use Session Cookies, since that would make more sense when working with SharePoint. You login you do your stuff, you might sign out, or you might close your browser. Next time you hit it, it asks you to login. I was happy, everyone else was happy. That is, until someone needed to work with SharePoint from within Outlook and though WebDAV.

SharePoint will standardly run with Persistent Cookies, but you can change this though PowerShell. Set UseSessionCookies to $true or $false. If you need to work with SharePoint though Office or WebDAV you need to set this to $false (default)

$snapin = Get-PSSnapin | where {$_.name -eq 'Microsoft.SharePoint.PowerShell'}
if($snapin -eq $null){ Add-PSSnapin Microsoft.SharePoint.PowerShell }

$sts = Get-SPSecurityTokenServiceConfig
$sts.UseSessionCookies = $false
$sts.Update()
iisreset

As far as I know, you cannot set this per site.

Next you want to make sure Office/Web Client can read the cookie. Referee to “Persistent cookies are not shared between Internet Explorer and Office applications”