Read Time:23 Second

Posted by Georgi Guninski on Apr 21

In short in Firefox 112, it is possible to check existence
of firewalled web servers. This doesn’t work in Chrome and Chromium 112
for me.

If user A has tcp connection to web server B, then in the
following html:

<iframe src=”http://B&quot; onload=”load()” onerror=”alert(‘error’)” id=”i1″ />

the javascript function load() will get executed if B serves
valid document to A’s browser…

Read More

More Stories