IssueTracker

What you would like to accomplish:

To use HMRC web services (in UK) there is a legislative requirement to send various headers for anti-fraud purposes. For example, HMRC require the Client's originating IP address, which we can extract from the X_Forwarded_For header.

But they also require the Client's Port Number, which is typically a random number provided by the clients network stack in the range: 49,152 - 65,535 and there appears to be no mechanism for extracting this value at present.

We thought the user-defined header options may allow this, but Client Port is not one of the available values.

So this request is to gain access to the Client Port value either via a new predefined X header or via the user-defined header options.

How this might work:

Option 1: Expose the Client Port via a new "X_Forwarded_Port" header
Option 2: Expose the Client Port as one of the available user-defined header values
Option 3: Modify X_Forwarded_For to display both IP and Port separated by a colon. i.e. 1.2.3.4:54321

Other information (workarounds you have tried, documentation consulted, etc):

Any workarounds we can think of involve not using google load balancer at all and instead moving to an alternative proxy running on a virtual instance, which is undesirable.