ISSUE: Can't RPC Proxy Outlook Anywhere requests for Exchange 2010 mailbox users via the Exchange 2013 CAS NLB IP.
SYMPTOMS: Externally with TestExchangeConnectivity.com, I get 'RPC Proxy Can't Be Pinged' with 'An HTTP 401 Unauthorized response was received from the remote Unknown server'. Internally, I get password prompts with Outlook 2010.
SETUP:
Exchange 2013 CU1
CAS NLB: exchange.mydomain.com
Get-OutlookAnywhere Details:
InternalHostname: exchange.mydomain.com
ExternalHostname: exchange.mydomain.com
ExternalClientAuthenticationMethod: Negotiate
InternalClientAuthenticationMethod: Ntlm
IISAuthenticationMethods: Basic, Ntlm, Negotiate
Exchange 2010 SP3
CAS NLB: legacy.mydomain.com
CAS Array: legacy.mydomain.com
Get-OutlookAnywhere Details:
ExternalHostname: exchange.mydomain.com
ClientAuthenticationMethod: Ntlm
IISAuthenticationMethods: Basic, Ntlm
ADDITIONAL DETAILS:
- With the above settings, Outlook 2010 configures the 'Exchange Proxy Settings' with exchange.mydomain.com and NTLM authentication, which is what I want. However, Outlook 2010 doesn't seem to be able to proxy through exchange.mydomain.com as I continually
get password prompts.
- If I change ExternalHostname on the Exchange 2010 side's OutlookAnywhere to legacy.mydomain.com, then Outlook 2010 uses legacy.mydomain.com for the 'Exchange Proxy Settings' and that works fine. However, I want all Outlook requests to be proxied through the
Exchange 2013 CAS servers.
- For users with Exchange 2013 mailboxes, they are able to use exchange.mydomain.com as their 'Exchange Proxy Settings' without any issues. The problem therefore lies with proxying RPC requests FROM 2013 to 2010.
- Here are some pertinent lines from a 2013 CAS server's IIS logs:
01:37:58 192.168.150.210 RPC_IN_DATA /rpc/rpcproxy.dll legacy.domain.com:6002&RequestId=d01bfb91-6fa7-47bb-a1c6-ba2cda921c3a 443 - 207.46.14.63 MSRPC - 401 2 5 15
2013-06-24 01:37:58 192.168.150.210 RPC_IN_DATA /Rpc/RpcProxy.dll legacy.domain.com:6001&RequestId=cbcd4706-9a34-499e-8b63-8b0e0b58e946 443 - 207.46.14.63 MSRPC - 401 1 2148074254 31
2013-06-24 01:37:58 192.168.150.210 RPC_IN_DATA /rpc/rpcproxy.dll &RequestId=114f4709-d614-4a6a-96e6-b33729d85cf1 443 - 207.46.14.63 MSRPC - 401 2 5 218
2013-06-24 01:37:58 192.168.150.210 RPC_IN_DATA /Rpc/RpcProxy.dll legacy.domain.com:6001&RequestId=5d1390b3-84c8-4402-849f-edefe37da159 443 DOMAIN\testuser 207.46.14.63 MSRPC - 401 0 0 62
2013-06-24 01:37:58 192.168.150.210 RPC_IN_DATA /Rpc/RpcProxy.dll legacy.domain.com:6001&RequestId=73f08b89-b71e-46c0-b3c6-5b9dbbacc5c4 443 - 207.46.14.63 MSRPC - 401 2 5 249
Any thoughts or comments are highly appreciated. Let me know if additional details are needed.