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If you are running the Jetty engine behind a proxy or load balancer Jetty has built-in support for forwarding the client address and other details via headers using its http-forwarded module, and after enabling it as above you can edit the resulting properties file to configure it.
Note that this example applies the forwarding rule to all ports, so if you also operate the server on other ports, those must also be proxied/protected or this will lead to exposures due to clients having the ability to smuggle in a false client address.
If your IdP is behind Apache, you probably only need it to listen for HTTP traffic locally. At present, this involves commenting out or removing two lines from the [depend] section of idp.mod: the lines containing https and ssl.
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