Apache: The Definitive Guide, 3rd Edition

Name

LimitRequestFields

Synopsis

LimitRequestFields number
Default: LimitRequestFields 100
Server config

number is an integer from 0 (meaning unlimited) to 32,767. The default value is defined by the compile-time constant DEFAULT_LIMIT_REQUEST_FIELDS (100 as distributed).

The LimitRequestFields directive allows the server administrator to modify the limit on the number of request header fields allowed in an HTTP request. A server needs this value to be larger than the number of fields that a normal client request might include. The number of request header fields used by a client rarely exceeds 20, but this may vary among different client implementations, often depending upon the extent to which a user has configured her browser to support detailed content negotiation. Optional HTTP extensions are often expressed using request-header fields.

This directive gives the server administrator greater control over abnormal client-request behavior, which may be useful for avoiding some forms of denial-of-service attacks. The value should be increased if normal clients see an error response from the server that indicates too many fields were sent in the request.