DDoS attack – request modification .htaccess

Goodmorning everyone,

**sorry my English**
I am receiving a couple of days a DDoS attack, and the provider a few hours ago I was contacted and asked to limit and enter an access restriction in .htaccess.
I get 2 million accesses with users using Linux with Chrome.
The provider has asked me to limit this couple: Operating system Linux with the use of browser Google Chrome.

What code should I put in .htaccess to block users who use Linux and Chrome?
Linux will just blocking even Android? because it is based on Linux?

Thanks a lot to everyone!