并且支持
multiple limit_conn
E.g. if you want to limit number of connections per ip *and* total
number of connections per virtual host.(即同时支持对对方ip和服务器自身的连接限制)
An IP address of the client serves as a key. Note that instead of $remote_addr, the $binary_remote_addr variable is used here, allowing to lower the size of a state down to 64 bytes. One megabyte zone can keep about 16 thousand 64-byte states. If the storage for a zone is exhausted, the server will return error 503 (Service Temporarily Unavailable) to all further requests.
The rate is specified in requests per second (r/s). If a rate of less than one request per second is desired, it is specified in request per minute (r/m). For example, half-request per second is 30r/m.