Assuming you have a database table setup for this, you can use the following code to perform you check:
// This function is taken from my own extension
public function getIpAddress()
$server = $this->app->input->server;
$clientIp = $server->get('HTTP_CLIENT_IP');
$httpFwd = $server->get('HTTP_X_FORWARDED_FOR');
The ‘Domain’ Attribute
• With domain set, cookies will be sent to that domain
and all its subdomains
• The risk with subdomains is lower than when scoped to
parent domain, but still relevant
• Remove domain attribute to limit cookie to origin host
– Important note: IE will always send to subdomains regardless
I went down this rabbit hole several years ago as a self-educating endeavor. You can go to the extent of leveraging a blend of server-side and client-side to sniff/frisk/detect a device.
The truth is that all data that you might wish to process:
can be spoofed/circumvented
can naturally fluctuate/vary enough to trip up your algorithm
can be missing ...
Just to clear a few things: I don't think there is anything that can tell this, not only in Joomla but in anything in the web. Under certain conditions you may be able to tell if a certain browser was at your site recently, e.g. like what G. Analytics does when counting new vs old visitors, which is a cookie based solution.
But there is no real accuracy on ...