Trace Chrome Proxy Selection with a NetLog Capture

Capture a Chrome NetLog and distinguish resolved proxy candidates from the route used by a particular request.

A settings dialog shows the configured policy. To investigate which route Chrome chose for one URL, capture the browser’s network events while that URL loads.

  1. Open chrome://net-export/ in Chrome.
  2. Start logging to disk and keep that tab open.
  3. In another tab, reproduce the specific navigation. Note the URL and approximate time.
  4. Return to the export tab and stop logging.

The resulting NetLog can be inspected with a compatible viewer. Use the capture’s default privacy setting unless additional detail is specifically needed; logs can reveal browsing and network information.

Read the request, then the proxy events

Find the target request and follow its related sources rather than searching the whole file for the first proxy hostname. Chrome may be loading unrelated tabs and background resources at the same time.

Proxy resolution returns an ordered list of candidates. For example, a hypothetical result might be:

PROXY proxy-a.example:8080; PROXY proxy-b.example:8080; DIRECT

This describes possible routes. It does not prove that proxy-a carried the request, or that all three routes were contacted.

Look for the resolved proxy list, any bad-proxy deprioritization or fallback events, and the associated connection or stream events. Follow through to the selected peer and final result. If a refresh is needed, distinguish PAC configuration state from remembered bad-proxy state. When a connection is reused, the request may point to an existing stream or socket rather than create a fresh TCP connection in that moment.

The event vocabulary includes PROXY_RESOLUTION_SERVICE_RESOLVED_PROXY_LIST and PROXY_LIST_FALLBACK. Depending on the resolution path, list details can appear as pac_string or proxy_info. Exported event types may be numeric and decoded through the constants recorded in the capture; a fixed number copied from another Chrome version is unreliable.

A DIRECT result for this URL can coexist with a proxy used by another URL. PAC decisions and bypass rules are destination-dependent. Preserve the specific request’s evidence when reporting the result.

Erthyglow kevrennek