Direct Access 2012 and Outlook RPC/HTTP

I have a client for whom i recently implemented 2012 Direct Access…. there was a number of teething problems in the implementation – but once its working, DA is actually pretty good.

If i could ask the product team for anything in DA 2012 R2, it would be

  • re-introduce wildcard certificate support (it was in UAG DA for 2008 R2, not sure why it got left out of 2012)
  • Make the status reporting dashboard check for local firewall status (that its on and that the rules have been correctly added) as part of its health check
  • Release Win7 SP2 and make it support “simple” DA auth (i know this isn’t going to happen… but it doesnt mean it wouldn’t be nice!)

Anyhoo….. at this particular client, they had decided to do one of my most hated things – use the same url internally and externally for the configuration of web services in exchange. I avoid this configuration where-ever possible…. although i understand at small sites where only one server is present – it may seem like the only option – solutions such as TMG (or another reverse publsiher), SAN certificates or creating additional exchange web services on different ports are all valid ways of getting around that config.

As to why it had been done at this client who is substantially larger…. well, the consultancy that did it…. i have very different views to them on good practices for exchange design…. and the client has a DAG without a load balanced CAS – so there is no true fail-over anyway…. grrr…. but i digress.

Due to the configuration of the same url’s internally and externally for web services, i added an entry into the DA NRPT so it would always resolve to the internal name…. issue is, that users were still getting prompted for auth, because the outlook client detected a slow connection and used RPC/HTTP, which is configured for basic auth (another config item i diagree with).

What i had not know before (because i hadnt needed to) was that you can disable RPC/HTTP on a per-mailbox basis…. using the command

Set-CASMailbox –Identity <alias> –MAPIBlockOutlookRpcHttp $True

While the better solution is to fix the exchange design (different URL’s and NTLM for RPC/HTTP) – its a handy work-around.

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