Hi, all

On our servers, the following UAs are blocked and similar repeated requests
against large iso files can be rejected:

map $http_user_agent $isbadbrowser {
 default 0;
 "~*Mozilla/5\.0 \(Linux; Android\)" 1;
 "~*Chrome/49\.0\.2623\.87" 1;
 "~*Firefox/3.6.3" 1;
}

According to our experience of operating largest mirror site in China, such
User-Agent list is able to protect against most of those traffic, IP blocking is
not needed and the list didn't require an update for several years.