doc: add note about remoteaddr strategy

docs/content/middlewares/http/inflightreq.md

@@ -127,6 +127,8 @@ If none are set, the default is to use the `requestHost`.
 
 The `ipStrategy` option defines two parameters that configures how Traefik determines the client IP: `depth`, and `excludedIPs`.
 
+!!! important "As a middleware, InFlightReq happens before the actual proxying to the backend takes place. In addition, the previous network hop only gets appended to `X-Forwarded-For` during the last stages of proxying, i.e. after it has already passed through the middleware. Therefore, during InFlightReq, as the previous network hop is not yet present in `X-Forwarded-For`, it cannot be used and/or relied upon."
+
 ##### `ipStrategy.depth`
 
 The `depth` option tells Traefik to use the `X-Forwarded-For` header and select the IP located at the `depth` position (starting from the right).

docs/content/middlewares/http/ipwhitelist.md

@@ -75,7 +75,10 @@ The `sourceRange` option sets the allowed IPs (or ranges of allowed IPs by using
 
 ### `ipStrategy`
 
-The `ipStrategy` option defines two parameters that set how Traefik determines the client IP: `depth`, and `excludedIPs`.
+The `ipStrategy` option defines two parameters that set how Traefik determines the client IP: `depth`, and `excludedIPs`.  
+If no strategy is set, the default behavior is to match `sourceRange` against the Remote address found in the request.
+
+!!! important "As a middleware, whitelisting happens before the actual proxying to the backend takes place. In addition, the previous network hop only gets appended to `X-Forwarded-For` during the last stages of proxying, i.e. after it has already passed through whitelisting. Therefore, during whitelisting, as the previous network hop is not yet present in `X-Forwarded-For`, it cannot be matched against `sourceRange`."
 
 #### `ipStrategy.depth`
 

docs/content/middlewares/http/ratelimit.md

@@ -262,6 +262,8 @@ If none are set, the default is to use the request's remote address field (as an
 
 The `ipStrategy` option defines two parameters that configures how Traefik determines the client IP: `depth`, and `excludedIPs`.
 
+!!! important "As a middleware, rate-limiting happens before the actual proxying to the backend takes place. In addition, the previous network hop only gets appended to `X-Forwarded-For` during the last stages of proxying, i.e. after it has already passed through rate-limiting. Therefore, during rate-limiting, as the previous network hop is not yet present in `X-Forwarded-For`, it cannot be found and/or relied upon."
+
 ##### `ipStrategy.depth`
 
 The `depth` option tells Traefik to use the `X-Forwarded-For` header and select the IP located at the `depth` position (starting from the right).