logging client IPs when running behind non-Zimbra nginx HTTP proxy

[bradfritz]

I have a test installation of ZCS running behind a non-Zimbra nginx
HTTP proxy on a separate host:

Internet --> Firewall (w/ public IP) --> nginx (172.x.x.10:443)
--> ZCS (172.x.x.113:443)

Is it possible to configure Zimbra so it trusts the reverse proxy
(172.x.x.10) and uses the X-Forwarded-For values provided by the
proxy server in mailbox.log and audit.log ?

Basically what I'm looking for is the mod_rpaf for Apache
equivalent for Zimbra.

Thanks for any help!

--Brad