# The Apache Tomcat 5.5 Servlet/JSP Container

# Apache Tomcat Configuration Reference

## The Valve Component

Table of Contents

> - Introduction
> - Access Log Valve
>   1. Introduction
>   2. Attributes
> - Remote Address Filter
>   1. Introduction
>   2. Attributes
> - Remote Host Filter
>   1. Introduction
>   2. Attributes
> - Request Dumper Valve
>   1. Introduction
>   2. Attributes
> - Single Sign On Valve
>   1. Introduction
>   2. Attributes
> - Basic Authenticator Valve
>   1. Introduction
>   2. Attributes
> - Digest Authenticator Valve
>   1. Introduction
>   2. Attributes
> - Form Authenticator Valve
>   1. Introduction
>   2. Attributes
> - SSL Authenticator Valve
>   1. Introduction
>   2. Attributes

Introduction

> A Valve element represents a component that will be inserted into the request processing pipeline for the associated Catalina container (Engine, Host, or Context). Individual Valves have distinct processing capabilities, and are described individually below.

> > The description below uses the variable name $CATALINA_HOME to refer to the directory into which you have installed Tomcat 5, and is the base directory against which most relative paths are resolved. However, if you have configured Tomcat 5 for multiple instances by setting a CATALINA_BASE directory, you should use $CATALINA_BASE instead of $CATALINA_HOME for each of these references.

Access Log Valve

> Introduction

> > The Access Log Valve creates log files in the same format as those created by standard web servers. These logs can later be analyzed by standard log analysis tools to track page hit counts, user session activity, and so on. The files produces by this `Valve` are rolled over nightly at midnight. This `Valve` may be associated with any Catalina container (`Context`, `Host`, or `Engine`), and will record ALL requests processed by that container.

> Attributes

> > The Access Log Valve supports the following configuration attributes:

> > Attribute | Description
> > --- | ---
> > `className` | Java class name of the implementation to use. This MUST be set to org.apache.catalina.valves.AccessLogValve to use the default access log valve. To use a more optimized access log valve designed for production use, you MUST set this attribute to org.apache.catalina.valves.FastCommonAccessLogValve. In this case, only the `common` and `combined` patterns are supported.
> > `directory` | Absolute or relative pathname of a directory in which log files created by this valve will be placed. If a relative path is specified, it is interpreted as relative to $CATALINA_HOME. If no directory attribute is specified, the default value is "logs" (relative to $CATALINA_HOME).
> > `pattern` | A formatting layout identifying the various information fields from the request and response to be logged, or the word `common` or `combined` to select a standard format. See below for more information on configuring this attribute. Note that the optimized access does only support `common` and `combined` as the value for this attribute.
> > `prefix` | The prefix added to the start of each log file's name. If not specified, the default value is "access_log.". To specify no prefix, use a zero-length string.
> > `resolveHosts` | Set to `true` to convert the IP address of the remote host into the corresponding host name via a DNS lookup. Set to `false` to skip this lookup, and report the remote IP address instead.
> > `suffix` | The suffix added to the end of each log file's name. If not specified, the default value is "". To specify no suffix, use a zero-length string.
> > `rotatable` | Default true. Flag to determine if log rotation should occur. If set to false, then this file is never rotated and `fileDateFormat` is ignored. Use with caution!
> > `condition` | Turns on conditional logging. If set, requests will be logged only if `ServletRequest.getAttribute()` is null. For example, if this value is set to `junk`, then a particular request will only be logged if `ServletRequest.getAttribute("junk") == null`. The use of Filters is an easy way to set/unset the attribute in the ServletRequest on many different requests.
> > `fileDateFormat` | Allows a customized date format in the access log file name. The date format also decides how often the file is rotated. If you wish to rotate every hour, then set this value to: `yyyy-MM-dd.HH`

> > Values for the `pattern` attribute are made up of literal text strings, combined with pattern identifiers prefixed by the "%" character to cause replacement by the corresponding variable value from the current request and response. The following pattern codes are supported:

> > - %a - Remote IP address
> > - %A - Local IP address
> > - %b - Bytes sent, excluding HTTP headers, or '-' if zero
> > - %B - Bytes sent, excluding HTTP headers
> > - %h - Remote host name (or IP address if `resolveHosts` is false)
> > - %H - Request protocol
> > - %l - Remote logical username from identd (always returns '-')
> > - %m - Request method (GET, POST, etc.)
> > - %p - Local port on which this request was received
> > - %q - Query string (prepended with a '?' if it exists)
> > - %r - First line of the request (method and request URI)
> > - %s - HTTP status code of the response
> > - %S - User session ID
> > - %t - Date and time, in Common Log Format
> > - %u - Remote user that was authenticated (if any), else '-'
> > - %U - Requested URL path
> > - %v - Local server name
> > - %D - Time taken to process the request, in millis
> > - %T - Time taken to process the request, in seconds
> > - %I - current request thread name (can compare later with stacktraces)

> > There is also support to write information from the cookie, incoming header, outgoing response headers, the Session or something else in the ServletRequest. It is modeled after the apache syntax:

> > - `%{xxx}i` for incoming request headers
> > - `%{xxx}o` for outgoing response headers
> > - `%{xxx}c` for a specific request cookie
> > - `%{xxx}r` xxx is an attribute in the ServletRequest
> > - `%{xxx}s` xxx is an attribute in the HttpSession

> > The shorthand pattern name `common` (which is also the default) corresponds to '%h %l %u %t "%r" %s %b'.

> > The shorthand pattern name `combined` appends the values of the `Referer` and `User-Agent` headers, each in double quotes, to the `common` pattern described in the previous paragraph.

Remote Address Filter

> Introduction

> > The Remote Address Filter allows you to compare the IP address of the client that submitted this request against one or more regular expressions, and either allow the request to continue or refuse to process the request from this client. A Remote Address Filter can be associated with any Catalina container (Engine, Host, or Context), and must accept any request presented to this container for processing before it will be passed on.

> > The syntax for regular expressions is different than that for 'standard' wildcard matching. Tomcat uses the `java.util.regex` package. Please consult the Java documentation for details of the expressions supported.

> Attributes

> > The Remote Address Filter supports the following configuration attributes:

> > Attribute | Description
> > --- | ---
> > `className` | Java class name of the implementation to use. This MUST be set to org.apache.catalina.valves.RemoteAddrValve.
> > `allow` | A comma-separated list of regular expression patterns that the remote client's IP address is compared to. If this attribute is specified, the remote address MUST match for this request to be accepted. If this attribute is not specified, all requests will be accepted UNLESS the remote address matches a `deny` pattern.
> > `deny` | A comma-separated list of regular expression patterns that the remote client's IP address is compared to. If this attribute is specified, the remote address MUST NOT match for this request to be accepted. If this attribute is not specified, request acceptance is governed solely by the `accept` attribute.

Remote Host Filter

> Introduction

> > The Remote Host Filter allows you to compare the hostname of the client that submitted this request against one or more regular expressions, and either allow the request to continue or refuse to process the request from this client. A Remote Host Filter can be associated with any Catalina container (Engine, Host, or Context), and must accept any request presented to this container for processing before it will be passed on.

> > The syntax for regular expressions is different than that for 'standard' wildcard matching. Tomcat uses the `java.util.regex` package. Please consult the Java documentation for details of the expressions supported.

> Attributes

> > The Remote Host Filter supports the following configuration attributes:

> > Attribute | Description
> > --- | ---
> > `className` | Java class name of the implementation to use. This MUST be set to org.apache.catalina.valves.RemoteHostValve.
> > `allow` | A comma-separated list of regular expression patterns that the remote client's hostname is compared to. If this attribute is specified, the remote hostname MUST match for this request to be accepted. If this attribute is not specified, all requests will be accepted UNLESS the remote hostname matches a `deny` pattern.
> > `deny` | A comma-separated list of regular expression patterns that the remote client's hostname is compared to. If this attribute is specified, the remote hostname MUST NOT match for this request to be accepted. If this attribute is not specified, request acceptance is governed solely by the `accept` attribute.

Request Dumper Valve

> Introduction

> > The Request Dumper Valve is a useful tool in debugging interactions with a client application (or browser) that is sending HTTP requests to your Tomcat-based server. When configured, it causes details about each request processed by its associated `Engine`, `Host`, or `Context` to be logged according to the logging configuration for that container.

> > WARNING: Using this valve has side-effects. The output from this valve includes any parameters included with the request. The parameters will be decoded using the default platform encoding. Any subsequent calls to `request.setCharacterEncoding()` within the web application will have no effect.

> > Note: this Valve is now deprecated in favor of the RequestDumperFilter, which does the same thing in a portable manner. This Filter is included in the examples application: see $CATALINA_HOME/webapps/examples/WEB-INF/classes/filters for the source.

> Attributes

> > The Request Dumper Valve supports the following configuration attributes:

> > Attribute | Description
> > --- | ---
> > `className` | Java class name of the implementation to use. This MUST be set to org.apache.catalina.valves.RequestDumperValve.

Single Sign On Valve

> Introduction

> > The Single Sign On Vale is utilized when you wish to give users the ability to sign on to any one of the web applications associated with your virtual host, and then have their identity recognized by all other web applications on the same virtual host.

> > See the Single Sign On special feature on the Host element for more information.

> Attributes

> > The Single Sign On Valve supports the following configuration attributes:

> > Attribute | Description
> > --- | ---
> > `className` | Java class name of the implementation to use. This MUST be set to org.apache.catalina.authenticator.SingleSignOn.

> > `requireReauthentication`

> > Default false. Flag to determine whether each request needs to be reauthenticated to the security Realm. If "true", this Valve uses cached security credentials (username and password) to reauthenticate to the Realm each request associated with an SSO session. If "false", the Valve can itself authenticate requests based on the presence of a valid SSO cookie, without rechecking with the Realm.

> > `cookieDomain` | Sets the host domain to be used for sso cookies.

Basic Authenticator Valve

> Introduction

> > The Basic Authenticator Valve is automatically added to any Context that is configured to use BASIC authentication.

> > If any non-default settings are required, the valve may be configured within Context element with the required values.

> Attributes

> > The Basic Authenticator Valve supports the following configuration attributes:

> > Attribute | Description
> > --- | ---
> > `className` | Java class name of the implementation to use. This MUST be set to org.apache.catalina.authenticator.BasicAuthenticator.
> > `changeSessionIdOnAuthentication` | Controls if the session ID is changed if a session exists at the point where users are authenticated. This is to prevent session fixation attacks. If not set, the default value of `false` will be used.

> > `disableProxyCaching`

> > Controls the caching of pages that are protected by security constraints. Setting this to `false` may help work around caching issues in some browsers but will also cause secured pages to be cached by proxies which will almost certainly be a security issue. `securePagesWithPragma` offers an alternative, secure, workaround for browser caching issues. If not set, the default value of `true` will be used.

> > `securePagesWithPragma` | Controls the caching of pages that are protected by security constraints. Setting this to `false` may help work around caching issues in some browsers by using `Cache-Control: private` rather than the default of `Pragma: No-cache` and `Cache-control: No-cache`. If not set, the default value of `true` will be used.

Digest Authenticator Valve

> Introduction

> > The Digest Authenticator Valve is automatically added to any Context that is configured to use DIGEST authentication.

> > If any non-default settings are required, the valve may be configured within Context element with the required values.

> Attributes

> > The Digest Authenticator Valve supports the following configuration attributes:

> > Attribute | Description
> > --- | ---
> > `className` | Java class name of the implementation to use. This MUST be set to org.apache.catalina.authenticator.DigestAuthenticator.
> > `changeSessionIdOnAuthentication` | Controls if the session ID is changed if a session exists at the point where users are authenticated. This is to prevent session fixation attacks. If not set, the default value of `false` will be used.
> > `cnonceCacheSize` | To protect against replay attacks, the DIGEST authenticator tracks client nonce and nonce count values. This attribute controls the size of that cache. If not specified, the default value of 1000 is used.

> > `disableProxyCaching`

> > Controls the caching of pages that are protected by security constraints. Setting this to `false` may help work around caching issues in some browsers but will also cause secured pages to be cached by proxies which will almost certainly be a security issue. `securePagesWithPragma` offers an alternative, secure, workaround for browser caching issues. If not set, the default value of `true` will be used.

> > `key` | The secret key used by digest authentication. If not set, a secure random value is generated. This should normally only be set when it is necessary to keep key values constant either across server restarts and/or across a cluster.
> > `nonceValidity` | The time, in milliseconds, that a server generated nonce will be considered valid for use in authentication. If not specified, the default value of 300000 (5 minutes) will be used.
> > `opaque` | The opaque server string used by digest authentication. If not set, a random value is generated. This should normally only be set when it is necessary to keep opaque values constant either across server restarts and/or across a cluster.
> > `securePagesWithPragma` | Controls the caching of pages that are protected by security constraints. Setting this to `false` may help work around caching issues in some browsers by using `Cache-Control: private` rather than the default of `Pragma: No-cache` and `Cache-control: No-cache`. If not set, the default value of `true` will be used.
> > `validateUri` | Should the URI be validated as required by RFC2617? If not specified, the default value of `true` will be used. This should normally only be set when Tomcat is located behind a reverse proxy and the proxy is modifying the URI passed to Tomcat such that DIGEST authentication always fails.

Form Authenticator Valve

> Introduction

> > The Form Authenticator Valve is automatically added to any Context that is configured to use FORM authentication.

> > If any non-default settings are required, the valve may be configured within Context element with the required values.

> Attributes

> > The Form Authenticator Valve supports the following configuration attributes:

> > Attribute | Description
> > --- | ---
> > `className` | Java class name of the implementation to use. This MUST be set to org.apache.catalina.authenticator.FormAuthenticator.
> > `changeSessionIdOnAuthentication` | Controls if the session ID is changed if a session exists at the point where users are authenticated. This is to prevent session fixation attacks. If not set, the default value of `false` will be used.
> > `characterEncoding` | Character encoding to use to read the username and password parameters from the request. If not set, the encoding of the request body will be used.

> > `disableProxyCaching`

> > Controls the caching of pages that are protected by security constraints. Setting this to `false` may help work around caching issues in some browsers but will also cause secured pages to be cached by proxies which will almost certainly be a security issue. `securePagesWithPragma` offers an alternative, secure, workaround for browser caching issues. If not set, the default value of `true` will be used.

> > `securePagesWithPragma` | Controls the caching of pages that are protected by security constraints. Setting this to `false` may help work around caching issues in some browsers by using `Cache-Control: private` rather than the default of `Pragma: No-cache` and `Cache-control: No-cache`. If not set, the default value of `true` will be used.

SSL Authenticator Valve

> Introduction

> > The SSL Authenticator Valve is automatically added to any Context that is configured to use SSL authentication.

> > If any non-default settings are required, the valve may be configured within Context element with the required values.

> Attributes

> > The SSL Authenticator Valve supports the following configuration attributes:

> > Attribute | Description
> > --- | ---
> > `className` | Java class name of the implementation to use. This MUST be set to org.apache.catalina.authenticator.SSLAuthenticator.
> > `changeSessionIdOnAuthentication` | Controls if the session ID is changed if a session exists at the point where users are authenticated. This is to prevent session fixation attacks. If not set, the default value of `false` will be used.

> > `disableProxyCaching`

> > Controls the caching of pages that are protected by security constraints. Setting this to `false` may help work around caching issues in some browsers but will also cause secured pages to be cached by proxies which will almost certainly be a security issue. `securePagesWithPragma` offers an alternative, secure, workaround for browser caching issues. If not set, the default value of `true` will be used.

> > `securePagesWithPragma` | Controls the caching of pages that are protected by security constraints. Setting this to `false` may help work around caching issues in some browsers by using `Cache-Control: private` rather than the default of `Pragma: No-cache` and `Cache-control: No-cache`. If not set, the default value of `true` will be used.

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