Некушает рег выражение (3 replies)

Пишу правило if ($http_user_agent ~* "Googlebot/2\.1.*" {
Nginx ругаеться
nginx -t
nginx: [emerg] invalid condition "Googlebot/2\.1.*"

цель правила порубить товарищей ддосеров такого вида:
211.138.121.38 - - [15/Jul/2015:17:45:36 +0200] "GET / HTTP/1.1" 200 137038 "-" "Googlebot/2.1 (+http://www.google.com/bot.html) 382426"
52.8.111.148 - - [15/Jul/2015:17:45:36 +0200] "GET / HTTP/1.1" 200 137038 "-" "Googlebot/2.1 (+http://www.google.com/bot.html) 192612"
222.124.29.244 - - [15/Jul/2015:17:45:36 +0200] "GET / HTTP/1.1" 200 137038 "-" "Googlebot/2.1 (+http://www.google.com/bot.html) 683083"
88.199.137.198 - - [15/Jul/2015:17:45:37 +0200] "GET / HTTP/1.1" 200 137038 "-" "Googlebot/2.1 (+http://www.google.com/bot.html) 612712"
120.194.215.70 - - [15/Jul/2015:17:45:38 +0200] "GET / HTTP/1.0" 200 137024 "-" "Googlebot/2.1 (+http://www.google.com/bot.html) 232004"
103.11.116.46 - - [15/Jul/2015:17:45:38 +0200] "GET / HTTP/1.1" 200 47302 "-" "Googlebot/2.1 (+http://www.google.com/bot.html) 217757"
111.1.3.36 - - [15/Jul/2015:17:45:39 +0200] "GET / HTTP/1.0" 200 137024 "-" "Googlebot/2.1 (+http://www.google.com/bot.html) 816202"
177.101.8.65 - - [15/Jul/2015:17:45:39 +0200] "GET / HTTP/1.1" 200 137038 "-" "Googlebot/2.1 (+http://www.google.com/bot.html) 153824"