proxy – How to filter urls with sub_filter with nginx


I've recently been given the task of configuring a proxy and everything is working fine now, except that I can not filter basic URLs with sub_filter.
This code works perfectly

sub_filter & # 39; anna & # 39; & # 39; & # 39 ;; bob

But the second, I add a slash to the search pattern, like this

sub_filter & # 39; / anna & # 39; & # 39; & # 39 ;; bob

The filter stops working. I tried to escape the slash with a backslash, but that also failed.

Is there a special regex that I am not aware of?
Thank you