User-agent: dotbot
Disallow: /

User-agent: MJ12bot
Disallow: /

User-agent: AhrefsBot
Disallow: /

User-agent: SemrushBot
Disallow: /

User-agent: Yandex
Disallow: / # blocks access to whole site

User-agent: *
Disallow: /admin
Disallow: /downloader