Follow the request through participating proxies
01A proxy forwards a request on a client’s behalf. Forwarded can report details that would otherwise be hidden by those separate connections.
In this separate alternative, P1 emits no field. P2 adds only for=198.51.100.17. The original client is missing; do not invent an entry or assume every hop participated.
Source for this drawing: RFC 7239 · Read RFC section 4 ↗
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A message needs an address.
Think of a packet as a small addressed envelope. Devices pass it onward; transport protocols decide what delivery promises an application gets.
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An entry describes one participating proxy’s incoming side.
- Forwarded is optional and request-only. Because its information is sensitive, it should be off by default, with each parameter configured individually.
- When entries are added, the first comes from the first participating proxy; later proxies append after a comma or add a field at the end of the header block. A proxy MAY remove all Forwarded fields.
- In a fully participating chain, for values identify the client and preceding proxies. The final proxy is visible to the origin as the transport peer; it is not another for entry for itself.
The example explicitly opts in to disclosure of documentation addresses. Not every proxy emits an entry, so this is not a guaranteed complete route. This is HTTP metadata, not a routing command or authentication proof.
Read the RFC section ↗