XTLS_Xray-docs-next/docs/en/config/outbounds/loopback.md

Loopback

Loopback is a loopback outbound used to send traffic back to routing for further processing without leaving the core.

::: tip Uses

• In places where only an outbound can be specified and balancerTag cannot be written directly, Loopback can be used to indirectly use a balancer.
  For example, dialerProxy in chained proxies, and fallbackTag in load balancing.
• After traffic has already been routed once, it can be further subdivided based on more conditions.
  For example, TCP traffic and UDP traffic routed by the same set of routing rules can be sent to different outbounds.

:::

::: warning Avoid Loops

Avoid letting rules or balancers after the loopback select the original outbound again, otherwise it may form an outbound -> Loopback -> routing -> original outbound loop.

:::

OutboundConfigurationObject

OutboundConfigurationObject corresponds to the settings item in OutboundObject.

{
  "outbounds": [
    {
      // ...
      "protocol": "loopback",
      // [!field focus]
      "settings": {
        "inboundTag": "TagUseAsInbound",
        "sniffing": {}
      }
    }
  ]
}

inboundTag: string

The inbound tag used when re-entering routing.

This tag can be used as inboundTag in routing, indicating that data from this outbound will re-enter routing with this tag and be processed again by the corresponding rules.

sniffing: SniffingObject

Traffic sniffing. The specific configuration is the same as that of Inbound. Disabled by default.