Constant DEFAULT_APM_NON_LOCAL_TRAFFIC 

pub const DEFAULT_APM_NON_LOCAL_TRAFFIC: bool = false;

Whether the APM v1.0 trace receiver accepts non-local traffic by default.

Defaults to false, so the receiver refuses to bind a non-loopback TCP address. Set this only when tracers run outside the host’s network namespace and the port is not reachable from untrusted networks.