---
name: "httpd_core"
section: "3erl"
platform: "linux"
package: "erlang-manpages"
version: "1:10.b.1a-1"
release: "Debian 3.1 (Sarge)"
platforms: ["linux"]
url: "https://new.carta.tech/httpd_core"
---

# httpd\_core(3erl)

The core functionality of the Web server.

## NAME

httpd\_core - The core functionality of the Web server.

## DESCRIPTION

This manual page summarize the core features of the server not being implemented as EWSAPI modules. The following core config directives are described:

### Note:

There is no erlang module called httpd\_core. This manual page is just a place to put the documentation for the core directives.

- \*

  BindAddress

- \*

  DefaultType

- \*

  DocumentRoot

- \*

  MaxBodyAction

- \*

  MaxBodySize

- \*

  MaxClients

- \*

  KeepAlive

- \*

  KeepAliveTimeout

- \*

  MaxHeaderAction

- \*

  MaxHeaderSize

- \*

  MaxKeepAliveRequests

- \*

  Modules

- \*

  Port

- \*

  ServerAdmin

- \*

  ServerName

- \*

  ServerRoot

- \*

  SocketType

- \*

  SSLCACertificateFile

- \*

  SSLCertificateFile

- \*

  SSLCertificateKeyFile

- \*

  SSLCiphers

- \*

  SSLPasswordCallbackFunction

- \*

  SSLPasswordCallbackModule

- \*

  SSLVerifyClient

- \*

  SSLVerifyDepth

- \*

  DisableChunkedTransferEncodingSend

## SECURE SOCKETS LAYER (SSL)

The SSL support is realized using the SSL application based on OpenSSL. Please refer to ssl(4) for installation requirements for OpenSSL.

SSLeay is an implementation of Netscape's Secure Socket Layer specification - the software encryption protocol specification behind the Netscape Secure Server and the Netscape Navigator Browser.

The SSL Protocol can negotiate an encryption algorithm and session key as well as authenticate a server before the application protocol transmits or receives it's first byte of data. All of the application protocol data is transmitted encrypted, ensuring privacy.

The SSL protocol provides "channel security" which has three basic properties:

- \*

  The channel is private. Encryption is used for all messages after a simple handshake is used to define a secret key.

- \*

  The channel is authenticated. The server end-point of the conversation is always authenticated, while the client endpoint is optionally authenticated.

- \*

  The channel is reliable. The message transport includes a message integrity check (using a MAC).

The SSL mechanism can be enabled in the server by using the SSLCACertificateFile, SSLCertificateFile, SSLCertificateKeyFile, SSLCiphers, SSLVerifyDepth, and the SSLVerifyClient config directives.

## MIME TYPE SETTINGS

Files delivered to the client are  MIME typed according to RFC 1590. File suffixes are mapped to MIME types before file delivery.

The mapping between file suffixes and MIME types are specified in the *mime.types* file. The *mime.types* reside within the *conf* directory of the ServerRoot. Refer to the example server root($INETS\_ROOT/examples/server\_root). MIME types may be added as required to the *mime.types* file and the DefaultType config directive can be used to specify a default mime type.

## DIRECTIVE: BindAddress

*Syntax:* *BindAddress* address\
\
  *Default:* *BindAddress \**\
\
  *Module:* httpd\_core(3)

*BindAddress* defines which address the server will listen to. If the argument is \* then the server listens to all addresses otherwise the server will only listen to the address specified. Address can be given either as an IP address or a hostname.

## DIRECTIVE: DefaultType

*Syntax:* *DefaultType* mime-type\
\
  *Default:* - None - *Module:* httpd\_core(3)

When the server is asked to provide a document type which cannot be determined by the MIME Type Settings, the server must inform the client about the content type of documents and *mime-type* is used if an unknown type is encountered.

## DIRECTIVE: DisableChunkedTransferEncodingSend

*Syntax:* *DisableChunkedTransferEncodingSend* true \| false\
\
  *Default:* false\
\
  *Module:* httpd\_core(3)

This directive tells the server whether to use chunked transfer-encoding when sending a response to a HTTP/1.1 client.

## DIRECTIVE: DocumentRoot

*Syntax:* *DocumentRoot* directory-filename\
\
  *Default:* - Mandatory - *Module:* httpd\_core(3)

*DocumentRoot* points the Web server to the document space from which to serve documents from. Unless matched by a directive like Alias, the server appends the path from the requested URL to the *DocumentRoot* to make the path to the document, for example:

```
DocumentRoot /usr/web
```

and an access to *http://your.server.org/index.html* would refer to */usr/web/index.html*.

## DIRECTIVE: KeepAlive

*Syntax:* *KeepAlive* true \| false\
\
  *Default:* true\
\
  *Module:* httpd\_core(3)

This directive tells the server whether to use persistent connection or not when the client claims to be HTTP/1.1 compliant.*Note:*the value of KeepAlive has changed from previous versions to be compliant with Apache.

## DIRECTIVE: KeepAliveTimeout

*Syntax:* *KeepAliveTimeout* seconds\
\
  *Default:*150\
\
  *Module:* httpd\_core(3)

The number of seconds the server will wait for a subsequent request from the client before closing the connection. If the load on the server is high you may want to shorten this.

## DIRECTIVE: MaxBodyAction

*Syntax:* *MaxBodyAction* action\
\
  *Default:* *MaxBodyAction close* *Module:* httpd\_core(3)

*MaxBodyAction* specifies the action to be taken when the message body limit has been passed.

- ***close*:**

  the default and preferred communication type. ip\_comm is also used for all remote message passing in Erlang.

- ***reply414*:**

  a reply (status) message with code 414 will be sent to the client *prior* to closing the socket. Note that this code is *not* defined in the HTTP/1.0 version of the protocol.

## DIRECTIVE: MaxBodySize

*Syntax:* *MaxBodySize* size\
\
  *Default:* *MaxBodySize nolimit* *Module:* httpd\_core(3)

*MaxBodySize* limits the *size* of the message body of HTTP request. The reply to this is specified by the *MaxBodyAction* directive. Valid size is:

- ***nolimit*:**

  the default message body limit, e.g. no limit.

- ***integer()*:**

  any positive number.

## DIRECTIVE: MaxClients

*Syntax:* *MaxClients* number\
\
  *Default:* *MaxClients 150* *Module:* httpd\_core(3)

*MaxClients* limits the *number* of simultaneous requests that can be supported. No more than this *number* of child server process's can be created.

## DIRECTIVE: MaxHeaderAction

*Syntax:* *MaxHeaderAction* action\
\
  *Default:* *MaxHeaderAction close* *Module:* httpd\_core(3)

*MaxHeaderAction* specifies the action to be taken when the message Header limit has been passed.

- ***close*:**

  the socket is closed without any message to the client. This is the default action.

- ***reply414*:**

  a reply (status) message with code 414 will be sent to the client *prior* to closing the socket. Note that this code is *not* defined in the HTTP/1.0 version of the protocol.

## DIRECTIVE: MaxHeaderSize

*Syntax:* *MaxHeaderSize* size\
\
  *Default:* *MaxHeaderSize 10240* *Module:* httpd\_core(3)

*MaxHeaderSize* limits the *size* of the message header of HTTP request. The reply to this is specified by the *MaxHeaderAction* directive. Valid size is:

- ***integer()*:**

  any positive number (default is 10240)

- ***nolimit*:**

  no limit should be applied

## DIRECTIVE: MaxKeepAliveRequests

*Syntax:* *MaxKeepAliveRequests* NumberOfRequests\
\
  *Default:*- Disabled -\
\
  *Module:* httpd\_core(3)

The number of request that a client can do on one connection. When the server has responded to the number of requests defined by MaxKeepAliveRequests the server close the connection. The server will close it even if there are queued request.

## DIRECTIVE: Modules

*Syntax:* *Modules* module module ...\
\
  *Default:* *Modules mod\_get mod\_head mod\_log*\
\
  *Module:* httpd\_core(3)

*Modules* defines which EWSAPI modules to be used in a specific server setup. *module* is a module in the code path of the server which has been written in accordance with the Erlang Web Server API in the Inets Users Guide.  The server executes functionality in each module, from left to right (from now on called *EWSAPI Module Sequence*).

Before altering the EWSAPI Modules Sequence please observe what types of data each module uses and propagates. Read the "EWSAPI Interaction" section for each module and the EWSAPI Module Interaction in the Inets Users Guide description in *httpd(3)*.

## DIRECTIVE: Port

*Syntax:* *Port* number\
\
  *Default:* *Port 80*\
\
  *Module:* httpd\_core(3)

*Port* defines which port *number* the server should use (0 to 65535). Certain port numbers are reserved for particular protocols, i.e. examine your OS characteristics(/etc/services) for a list of reserved ports. The standard port for HTTP is 80.

All ports numbered below 1024 are reserved for system use and regular (non-root) users cannot use them, i.e. to use port 80 you must start the Erlang node as root. (sic!) If you do not have root access choose an unused port above 1024 typically 8000, 8080 or 8888.

## DIRECTIVE: ServerAdmin

*Syntax:* *ServerAdmin* email-address\
\
  *Default:* *ServerAdmin unknown@unknown*\
\
  *Module:* httpd\_core(3)

*ServerAdmin* defines the *email-address* of the server administrator, to be included in any error messages returned by the server. It may be worth setting up a dedicated user for this because clients do not always state which server they have comments about, for example:

```
ServerAdmin www-admin@white-house.com
```

## DIRECTIVE: ServerName

*Syntax:* *ServerName* fully-qualified domain name\
\
  *Default:* - Mandatory - \
\
  *Module:* httpd\_core(3)

*ServerName* sets the *fully-qualified domain name* of the server.

## DIRECTIVE: ServerRoot

*Syntax:* *ServerRoot* directory-filename\
\
  *Default:* - Mandatory -\
\
  *Module:* httpd\_core(3)

*ServerRoot* defines a *directory-filename* where the server has it's operational home, e.g. used to store log files and system icons. Relative paths specified in the config file refer to this *directory-filename* (See mod\_log(3)).

## DIRECTIVE: SocketType

*Syntax:* *SocketType* type\
\
  *Default:* *SocketType ip\_comm*\
\
  *Module:* httpd\_core(3)

*SocketType* defines which underlying communication *type* to be used. Valid socket types are:

- ***ip\_comm*:**

  the default and preferred communication type. ip\_comm is also used for all remote message passing in Erlang.

- ***ssl*:**

  the communication type to be used to support SSL (Read more about Secure Sockets Layer (SSL) in *httpd(3)*).

## DIRECTIVE: SSLCACertificateFile

*Syntax:* *SSLCACertificateFile* filename\
\
  *Default:* - None -\
\
  *Module:* httpd\_core(3)

*SSLCACertificateFile* points at a PEM encoded certificate of the certification authorities. Read more about PEM encoded certificates in the SSL application documentation. Read more about PEM encoded certificates in the SSL application documentation.

## DIRECTIVE: SSLCertificateFile

*Syntax:* *SSLCertificateFile* filename\
\
  *Default:* - None -\
\
  *Module:* httpd\_core(3)

*SSLCertificateFile* points at a PEM encoded certificate. Read more about PEM encoded certificates in the SSL application documentation. The dummy certificate server.pem($INETS/examples/server\_root/ssl/), in the Inets distribution, can be used for test purposes. Read more about PEM encoded certificates in the SSL application documentation.

## DIRECTIVE: SSLCertificateKeyFile

*Syntax:* *SSLCertificateKeyFile* filename\
\
  *Default:* - None -\
\
  *Module:* httpd\_core(3)

*SSLCertificateKeyFile* is used to point at a certificate key file. This directive should only be used if a certificate key has not been bundled with the certificate file pointed at by SSLCertificateFile.

## DIRECTIVE: SSLVerifyClient

*Syntax:* *SSLVerifyClient* type\
\
  *Default:* - None -\
\
  *Module:* httpd\_core(3)

Set *type* to:

- **0:**

  if no client certificate is required.

- **1:**

  if the client *may* present a valid certificate.

- **2:**

  if the client *must* present a valid certificate.

- **3:**

  if the client *may* present a valid certificate but it is *not* required to have a valid CA.

Read more about SSL in the application documentation.

## DIRECTIVE: SSLVerifyDepth

*Syntax:* *SSLVerifyDepth* integer\
\
  *Default:* - None -\
\
  *Module:* httpd\_core(3)

This directive specifies how far up or down the (certification) chain we are prepared to go before giving up.

Read more about SSL in the application documentation.

## DIRECTIVE: SSLCiphers

*Syntax:* *SSLCiphers* ciphers\
\
  *Default:* - None - \
\
  *Module:* httpd\_core(3)

*SSLCihers* is a colon separated list of ciphers.

Read more about SSL in the application documentation.

## DIRECTIVE: SSLPasswordCallbackFunction

*Syntax:* *SSLPasswordCallbackFunction* function\
\
  *Default:* - None - \
\
  *Module:* httpd\_core(3)

The *SSLPasswordCallbackFunction* function in module *SSLPasswordCallbackModule* is called in order to retrieve the user's password.

Read more about SSL in the application documentation.

## DIRECTIVE: SSLPasswordCallbackModule

*Syntax:* *SSLPasswordCallbackModule* function\
\
  *Default:* - None - \
\
  *Module:* httpd\_core(3)

The *SSLPasswordCallbackFunction* function in the *SSLPasswordCallbackModule* module is called in order to retrieve the user's password.

Read more about SSL in the application documentation.

## SEE ALSO

httpd(3)

## AUTHOR

```
Joakim Grebenö  - support@erlang.ericsson.se
```