Reverse Proxy Planning

A critical piece in planning for Edge services is the reverse proxy. Unfortunately, this tends to be overlooked or considered a secondary task, even though it provides some important functionality to a deployment. Without a reverse proxy the following features will not work:

• Lync Mobile clients

• Address book download

• Distribution group expansion

• Web conferencing content such as whiteboards, uploaded presentations, and document sharing

• Device updates

• Dial-in conferencing page

• Simple meet conferencing pages

The first item might be a bit of a surprise, but the mobile clients for Lync use HTTPS web services to encapsulate the SIP signaling information. Organizations that neglect planning for a reverse proxy are effectively preventing their users from using Lync Mobile clients.

The concept of a reverse proxy is simple to understand when considering it as an extra hop or barrier between external clients and an internal resource. What a reverse proxy offers is the capability to inspect the traffic a client sends for any malicious requests, or possibly even pre-authenticates the user before being allowed to reach an internal client. In the overall scheme of external services, the reverse proxy fits in as depicted in Figure 31.9.

Figure 31.9. Reverse proxy for web services.