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Restricting OWA / ActiveSync Access

We need to configure Exchange Online so that users are only able to access OWA / ActiveSync from the company network, e.g. all remote users are required to connect to the network via an existing VPN.

Is it possible to restrict OWA and ActiveSync to a single public IP address or is there any other solution which will achieve this. I've heard that it may be possible to do this with ADFS, however we don't want to introduce that level of additional complexity / on-premise servers.
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Ivan
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Hi there,

this is a new one for me :)

I guess if you were to block SSL port to Exchange, eg. disable that NAT rule, no1 from outside would be able to connect to OWA. In the same time Outlook Anywhere would not work..
You could introduce policy to quarantine mobile devices and decide which one should be able to connect..but that is not quite what is your requirement.

Maybe some1 got some better solutions :)

Regards,
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Waddah Dahah

Hi,

Remove any public DNS record that point to your exchange i.e (Autodiscover, webmail,etc..)
Remove the publishing rule in your firewall that allow 443 or 80 to your CAS server.
Configure internal DNS with your exchange records i.e (Autodiscover, webmail,etc..)
your client DNS setting when they connect via VPN should point to your internal DNS server.

Regards,
Waddah
He cannot remove public DNS records if he is using them for POP/IMAP or such services.

Regards,
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ASKER

Surely blocking anything locally on-premise isn't going to help because a laptop user can connect to an Internet connection anywhere and connect to the Office 365 portal to access OWA?
ASKER CERTIFIED SOLUTION
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Vasil Michev (MVP)
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