This document explains some of the directives provided by the core server which are used to configure the basic operations of the server.
Related Directives ServerName ServerAdmin ServerSignature ServerTokens UseCanonicalName |
The ServerAdmin
and ServerTokens
directives control what information about the server will be
presented in server-generated documents such as error messages. The
ServerTokens
directive sets the value of the Server
HTTP response header field.
The ServerName
and UseCanonicalName
directives are used by the server to determine how to construct
self-referential URLs. For example, when a client requests a
directory, but does not include the trailing slash in the directory
name, Apache must redirect the client to the full name including
the trailing slash so that the client will correctly resolve
relative references in the document.
Related Directives CoreDumpDirectory DocumentRoot ErrorLog Lockfile PidFile ScoreBoardFile ServerRoot |
These directives control the locations of the various files that
Apache needs for proper operation. When the pathname used does not
begin with a slash "/", the files are located relative to the
ServerRoot
. Be careful about locating files in paths
which are writable by non-root users. See the security tips documentation for
more details.
Related Directives BS2000Account Group MaxClients MaxRequestsPerChild MaxSpareServers MinSpareServers ServerType StartServers ThreadsPerChild User |
When ServerType
is set to its recommended value of
Standalone
, Apache 1.3 for Unix is a pre-forking web
server. A single control process is responsible for launching child
processes which listen for connections and serve them when they
arrive. Apache always tries to maintain several spare or
idle server processes, which stand ready to serve incoming
requests. In this way, clients do not need to wait for a new child
processes to be forked before their requests can be served.
The StartServers
, MinSpareServers
,
MaxSpareServers
, and MaxServers
regulate
how the parent process creates children to serve requests. In
general, Apache is very self-regulating, so most sites do not need
to adjust these directives from their default values. Sites which
need to serve more than 256 simultaneous requests may need to
increase MaxClients
, while sites with limited memory
may need to decrease MaxClients
to keep the server
from thrashing (swapping memory to disk and back). More information
about tuning process creation is provided in the performance hints
documentation.
While the parent process is usually started as root under Unix
in order to bind to port 80, the child processes are launched by
Apache as a less-privileged user. The User
and
Group
directives are used to set the privileges of the
Apache child processes. The child processes must be able to read
all the content that will be served, but should have as few
privileges beyond that as possible. In addition, unless suexec is used, these directives also set
the privileges which will be inherited by CGI scripts.
MaxRequestsPerChild
controls how frequently the
server recycles processes by killing old ones and launching new
ones.
Under Windows, Apache launches one control process and one child
process. The child process creates multiple threads to serve
requests. The number of threads is controlled by the
ThreadsPerChild
directive.
Related Directives BindAddress KeepAlive KeepAliveTimeout Listen ListenBackLog AcceptFilter AcceptMutex MaxKeepAliveRequests Port SendBufferSize TimeOut |
When Apache starts, it connects to some port and address on the
local machine and waits for incoming requests. By default, it
listens to all addresses on the machine, and to the port as
specified by the Port
directive in the server
configuration. However, it can be told to listen to more than one
port, to listen to only selected addresses, or a combination. This
is often combined with the Virtual
Host feature which determines how Apache responds to different
IP addresses, hostnames and ports.
There are two directives used to restrict or specify which
addresses and ports Apache listens to. The BindAddress
directive is used to restrict the server to listening to a single
IP address. The Listen
directive can be used to
specify multiple IP addresses and/or Ports to which Apache will
listen.
The ListenBackLog
, SendBufferSize
, and
TimeOut
directives are used to adjust how Apache
interacts with the network.AcceptFilter
controls a BSD
specific filter optimization. See the BSD section on
performance hints documentation. AcceptMutex
controls which accept mutex method will be used. For an explanation
of what this is and why it's needed, see the performance tuning guide
The KeepAlive
, KeepAliveTimeout
, and
MaxKeepAliveRequests
directives are used to configure
how Apache handles persistent connections.
Related Directives LimitRequestBody LimitRequestFields LimitRequestFieldsize LimitRequestLine RLimitCPU RLimitMEM RLimitNPROC ThreadStackSize |
The LimitRequest
* directives are used to place
limits on the amount of resources Apache will use in reading
requests from clients. By limiting these values, some kinds of
denial of service attacks can be mitigated.
The RLimit
* directives are used to limit the amount
of resources which can be used by processes forked off from the
Apache children. In particular, this will control resources used by
CGI scripts and SSI exec commands.
The ThreadStackSize
directive is used only on
Netware to control the stack size.