# OnionPortMapping A single virtual-port → target mapping advertised by an onion service. ``` struct OnionPortMapping ``` ## Overview Corresponds to one `Port=,` entry in an `ADD_ONION` command (control-spec.txt §3.27). One [`OnionService`](/documentation/Tor/OnionService) can carry multiple mappings — e.g. port 80 to a web server, port 443 to the same server for TLS termination — by passing an array of these to [`addOnion(key:ports:detach:)`](/documentation/Tor/TorControlClient/addOnion(key:ports:detach:)). > Note: Conformance is `Sendable` + `Hashable` so collections of > mappings can be deduplicated and compared verbatim. > Important: The virtual port lives in the `.onion` namespace (what > clients dial); the target lives in the process’s kernel address > space. They are independent and do not need to match. ## Topics ### Creating [`init(virtualPort:target:)`](/documentation/Tor/OnionPortMapping/init(virtualPort:target:)) Construct a mapping from an explicit virtual port and target. [`toLocalPort(_:localPort:)`](/documentation/Tor/OnionPortMapping/toLocalPort(_:localPort:)) Convenience factory for loopback TCP mappings. ### Inspection [`virtualPort`](/documentation/Tor/OnionPortMapping/virtualPort) The TCP port exposed on the `.onion` address. [`target`](/documentation/Tor/OnionPortMapping/target) Where Tor should forward connections that arrive on [`virtualPort`](/documentation/Tor/OnionPortMapping/virtualPort).