Cache Test

The Lagado Cache Test will help expose stealthed transparent proxy caches. Stealthed transparent proxy caches are those which do not announce themselves to the origin web server and can appear to behave like a normal client. They may even masquerade as a client to make their requests.

This test is very simple but requires a little work from you.

page serial number	205851
page generation time
page age

Note: page generation time and page age are valid only when your device clock is set for accurate time.
 

Please follow the steps below.

Step 1

Note the page serial number somewhere.

Step 2

Clear your browser's cache

Chrome

Menu button > History > Clear Browsing Data ... > Make sure everything except "Cached images and files" is unchecked > Clear browsing data
 

Firefox

History button > History > Clear Recent History... > Uncheck everything except "Cache" > OK
 

Safari

Menu bar > Safari > Empty cache... > Empty
 

Step 3

Click on this link to load this page again. (Alternatively, you may browse to this page or use a bookmark. Do not hit refresh.)

If the page serial number is the same as when you noted it at step 1 you are most likely using a caching proxy; stop here - Proxy Found.

If the page serial number has changed you may not be using a caching proxy. To be more certain check the page age.

The page age shown is only valid when your device is set for accurate time (a few seconds error won't matter). If you adjust the time start again at step 1.

If the page age is no more than a few seconds there is no evidence of caching occuring so a proxy is not evident; stop here - No Proxy Found

If the page age is more than 30 seconds you may have picked up a fresher version of this page loaded into a proxy cache by someone else. It may be worth repeating the test to see if you get a more conclusive result.

 

Background Discussion

This test makes unique pages that behave as static pages. Caches operate on static pages because they can usually rely on them staying valid for a period of time.

These pages set a last modified date of three days before they are generated. They also set an expiry time of three days days into the future. This should encourage most caches to serve future requests for this page from the cache unless explicitly bypassed with the browser refresh button.

The tricky part of this test is to make sure that you are not just getting the page from the browser's local cache. Notice how each time you visit the cache-test (without hitting refresh or clearing the browser's cache) it gives you the same version which it is getting from the browser's cache.

This test will only expose caching proxies. It will not expose proxies that have some other goal or those that are selective about which sites they cache.

 

Selected Request Headers

The following headers were among those received with the request that generated this page. These headers affect the behaviour of caches.

Connection: keep-alive

Selected Response Headers For This Page

The Lagado server added the following headers to the response to affect the behaviour of caches.

Last-Modified: Wed, 18 Dec 2024 14:03:43 GMT
Expires: Tue, 24 Dec 2024 14:03:43 GMT
Cache-Control: max-age=259200
Date: Sat, 21 Dec 2024 14:03:43 GMT