Questions regarding trimming User-Name attribute via filter.

Hi. I'm having issues with migrating from 2.1.0 to 3.0.4 (Centos 7.x). In version 2.1.0 I have in /etc/freeradius/users: DEFAULT User-Name =~ ".{5}$" User-Name = `%{0}` This does not work anymore, and I am struggling to understand how to achieve the same thing in 3.0.4. What I want to achieve is, that anything that comes before the last five characters should be removed from the User-Name attribute, and only the last five characters should be left as User-Name. I understand that I have to do this in /etc/raddb/policy.d/filter somehow, but I fail to see how. Would somebody with better knowledge please assist. BR, /PGE