How to find the browser ID?

Question

PHP

I think most of you have worked with push notifications from the web environment.
There is a question - is it possible to somehow find out the Browser ID that is used to send notifications using "your" (preferably from PHP) methods?
Because registering a Push channel just for this is stupid, but you only need this same Browser ID.

Answer 1

Do you mean user agent?
$_SERVER["HTTP_USER_AGENT"];

Answer 2

you don’t recognize
it yourself you generate it
like this https://habrahabr.ru/company/oleg-bunin/blog/321294/
or just user agent*IP*time