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<!DOCTYPE document [
  <!ENTITY project SYSTEM "project.xml">
]>
<document url="http.html">

  &project;

  <properties>
    <author email="craigmcc@apache.org">Craig R. McClanahan</author>
    <author email="yoavs@apache.org">Yoav Shapira</author>
    <title>The HTTP Connector</title>
  </properties>

<body>

<section name="Table of Contents">
<toc/>
</section>

<section name="Introduction">

  <p>The <strong>HTTP Connector</strong> element represents a
  <strong>Connector</strong> component that supports the HTTP/1.1 protocol.
  It enables Catalina to function as a stand-alone web server, in addition
  to its ability to execute servlets and JSP pages.  A particular instance
  of this component listens for connections on a specific TCP port number
  on the server.  One or more such <strong>Connectors</strong> can be
  configured as part of a single <a href="service.html">Service</a>, each
  forwarding to the associated <a href="engine.html">Engine</a> to perform
  request processing and create the response.</p>

  <p>If you wish to configure the <strong>Connector</strong> that is used
  for connections to web servers using the AJP protocol (such as the
  <code>mod_jk 1.2.x</code> connector for Apache 1.3), please refer to the
  <a href="ajp.html">AJP Connector</a> documentation.</p>

  <p>Each incoming request requires
  a thread for the duration of that request.  If more simultaneous requests
  are received than can be handled by the currently available request
  processing threads, additional threads will be created up to the
  configured maximum (the value of the <code>maxThreads</code> attribute).
  If still more simultaneous requests are received, they are stacked up
  inside the server socket created by the <strong>Connector</strong>, up to
  the configured maximum (the value of the <code>acceptCount</code>
  attribute).  Any further simultaneous requests will receive "connection
  refused" errors, until resources are available to process them.</p>

</section>


<section name="Attributes">

  <subsection name="Common Attributes">

  <p>All implementations of <strong>Connector</strong>
  support the following attributes:</p>

  <attributes>

    <attribute name="allowBackslash" required="false">
      <p>If this is <code>true</code> the '\' character will be permitted as a
      path delimiter.</p>
      <p>If not specified, the default value of <code>false</code> will be used.</p>
    </attribute>

    <attribute name="allowTrace" required="false">
      <p>A boolean value which can be used to enable or disable the TRACE
      HTTP method. If not specified, this attribute is set to false.</p>
    </attribute>

    <attribute name="asyncTimeout" required="false">
      <p>The default timeout for asynchronous requests in milliseconds. If not
      specified, this attribute is set to the Servlet specification default of
      30000 (30 seconds).</p>
    </attribute>

    <attribute name="defaultSSLHostConfigName" required="false">
      <p>The name of the default <strong>SSLHostConfig</strong> that will be
      used for secure connections (if this connector is configured for secure
      connections) if the client connection does not provide SNI or if the SNI
      is provided but does not match any configured
      <strong>SSLHostConfig</strong>. If not specified the default value of
      <code>_default_</code> will be used.</p>
    </attribute>

    <attribute name="discardFacades" required="false">
      <p>A boolean value which can be used to enable or disable the recycling
      of the facade objects that isolate the container internal request
      processing objects. If set to <code>true</code> the facades will be
      set for garbage collection after every request, otherwise they will be
      reused. This setting has no effect when the security manager is enabled.
      If not specified, this attribute is set to <code>true</code>.</p>
    </attribute>

    <attribute name="enableLookups" required="false">
      <p>Set to <code>true</code> if you want calls to
      <code>request.getRemoteHost()</code> to perform DNS lookups in
      order to return the actual host name of the remote client.  Set
      to <code>false</code> to skip the DNS lookup and return the IP
      address in String form instead (thereby improving performance).
      By default, DNS lookups are disabled.</p>
    </attribute>

    <attribute name="encodedSolidusHandling" required="false">
      <p>When set to <code>reject</code> request paths containing a
      <code>%2f</code> sequence will be rejected with a 400 response. When set
      to <code>decode</code> request paths containing a <code>%2f</code>
      sequence will have that sequence decoded to <code>/</code> at the same
      time other <code>%nn</code> sequences are decoded. When set to
      <code>passthrough</code> request paths containing a <code>%2f</code>
      sequence will be processed with the <code>%2f</code> sequence unchanged.
      If not specified the default value is <code>reject</code>.</p>
    </attribute>

    <attribute name="enforceEncodingInGetWriter" required="false">
      <p>If this is <code>true</code> then
      a call to <code>Response.getWriter()</code> if no character encoding
      has been specified will result in subsequent calls to
      <code>Response.getCharacterEncoding()</code> returning
      <code>ISO-8859-1</code> and the <code>Content-Type</code> response header
      will include a <code>charset=ISO-8859-1</code> component. (SRV.15.2.22.1)</p>
      <p>If not specified, the default specification compliant value of
      <code>true</code> will be used.</p>
    </attribute>

    <attribute name="maxHeaderCount" required="false">
      <p>The maximum number of headers in a request that are allowed by the
      container. A request that contains more headers than the specified limit
      will be rejected. A value of less than 0 means no limit.
      If not specified, a default of 100 is used.</p>
    </attribute>

    <attribute name="maxParameterCount" required="false">
      <p>The maximum number of parameter and value pairs (GET plus POST) which
      will be automatically parsed by the container. Parameter and value pairs
      beyond this limit will be ignored. A value of less than 0 means no limit.
      If not specified, a default of 10000 is used. Note that
      <code>FailedRequestFilter</code> <a href="filter.html">filter</a> can be
      used to reject requests that hit the limit.</p>
    </attribute>

    <attribute name="maxPostSize" required="false">
      <p>The maximum size in bytes of the POST which will be handled by
      the container FORM URL parameter parsing. The limit can be disabled by
      setting this attribute to a value less than zero. If not specified, this
      attribute is set to 2097152 (2 megabytes). Note that the
      <a href="filter.html#Failed_Request_Filter"><code>FailedRequestFilter</code></a>
      can be used to reject requests that exceed this limit.</p>
    </attribute>

    <attribute name="maxSavePostSize" required="false">
      <p>The maximum size in bytes of the POST which will be saved/buffered by
      the container during FORM or CLIENT-CERT authentication. For both types
      of authentication, the POST will be saved/buffered before the user is
      authenticated. For CLIENT-CERT authentication, the POST is buffered for
      the duration of the SSL handshake and the buffer emptied when the request
      is processed. For FORM authentication the POST is saved whilst the user
      is re-directed to the login form and is retained until the user
      successfully authenticates or the session associated with the
      authentication request expires. The limit can be disabled by setting this
      attribute to -1. Setting the attribute to zero will disable the saving of
      POST data during authentication. If not specified, this attribute is set
      to 4096 (4 kilobytes).</p>
    </attribute>

    <attribute name="parseBodyMethods" required="false">
      <p>A comma-separated list of HTTP methods for which request
      bodies using <code>application/x-www-form-urlencoded</code> will be parsed
      for request parameters identically to POST. This is useful in RESTful
      applications that want to support POST-style semantics for PUT requests.
      Note that any setting other than <code>POST</code> causes Tomcat
      to behave in a way that goes against the intent of the servlet
      specification.
      The HTTP method TRACE is specifically forbidden here in accordance
      with the HTTP specification.
      The default is <code>POST</code></p>
    </attribute>

    <attribute name="port" required="true">
      <p>The TCP port number on which this <strong>Connector</strong>
      will create a server socket and await incoming connections.  Your
      operating system will allow only one server application to listen
      to a particular port number on a particular IP address. If the special
      value of 0 (zero) is used, then Tomcat will select a free port at random
      to use for this connector. This is typically only useful in embedded and
      testing applications.</p>
    </attribute>

    <attribute name="protocol" required="false">
      <p>Sets the protocol to handle incoming traffic. The default value is
        <code>HTTP/1.1</code> which uses a Java NIO based connector.<br/>
        To use an explicit protocol, the following values may be used:<br/>
        <code>org.apache.coyote.http11.Http11NioProtocol</code> -
              non blocking Java NIO connector<br/>
        <code>org.apache.coyote.http11.Http11Nio2Protocol</code> -
              non blocking Java NIO2 connector<br/>
        <code>org.apache.coyote.http11.Http11AprProtocol</code> -
              the APR/native connector.<br/>
        Custom implementations may also be used.<br/>
        Take a look at our <a href="#Connector_Comparison">Connector
        Comparison</a> chart. The configuration for both Java connectors is
        identical, for http and https.<br/>
        For more information on the APR connector and APR specific SSL settings
        please  visit the <a href="../apr.html">APR documentation</a>
      </p>
    </attribute>

    <attribute name="proxyName" required="false">
      <p>If this <strong>Connector</strong> is being used in a proxy
      configuration, configure this attribute to specify the server name
      to be returned for calls to <code>request.getServerName()</code>.
      See <a href="#Proxy_Support">Proxy Support</a> for more
      information.</p>
    </attribute>

    <attribute name="proxyPort" required="false">
      <p>If this <strong>Connector</strong> is being used in a proxy
      configuration, configure this attribute to specify the server port
      to be returned for calls to <code>request.getServerPort()</code>.
      See <a href="#Proxy_Support">Proxy Support</a> for more
      information.</p>
    </attribute>

    <attribute name="redirectPort" required="false">
      <p>If this <strong>Connector</strong> is supporting non-SSL
      requests, and a request is received for which a matching
      <code>&lt;security-constraint&gt;</code> requires SSL transport,
      Catalina will automatically redirect the request to the port
      number specified here.</p>
    </attribute>

    <attribute name="scheme" required="false">
      <p>Set this attribute to the name of the protocol you wish to have
      returned by calls to <code>request.getScheme()</code>.  For
      example, you would set this attribute to "<code>https</code>"
      for an SSL Connector.  The default value is "<code>http</code>".
      </p>
    </attribute>

    <attribute name="secure" required="false">
      <p>Set this attribute to <code>true</code> if you wish to have
      calls to <code>request.isSecure()</code> to return <code>true</code>
      for requests received by this Connector. You would want this on an
      SSL Connector or a non SSL connector that is receiving data from a
      SSL accelerator, like a crypto card, an SSL appliance or even a webserver.
      The default value is <code>false</code>.</p>
    </attribute>

    <attribute name="URIEncoding" required="false">
      <p>This specifies the character encoding used to decode the URI bytes,
      after %xx decoding the URL. The default value is <code>UTF-8</code>.</p>
    </attribute>

    <attribute name="useBodyEncodingForURI" required="false">
      <p>This specifies if the encoding specified in contentType should be used
      for URI query parameters, instead of using the URIEncoding. This
      setting is present for compatibility with Tomcat 4.1.x, where the
      encoding specified in the contentType, or explicitly set using
      Request.setCharacterEncoding method was also used for the parameters from
      the URL. The default value is <code>false</code>.
      </p>
      <p><strong>Notes:</strong> 1) This setting is applied only to the
      query string of a request. Unlike <code>URIEncoding</code> it does not
      affect the path portion of a request URI. 2) If request character
      encoding is not known (is not provided by a browser and is not set by
      <code>SetCharacterEncodingFilter</code> or a similar filter using
      Request.setCharacterEncoding method), the default encoding is always
      "ISO-8859-1". The <code>URIEncoding</code> setting has no effect on
      this default.
      </p>
    </attribute>

    <attribute name="useIPVHosts" required="false">
      <p>Set this attribute to <code>true</code> to cause Tomcat to use
      the IP address that the request was received on to determine the Host
      to send the request to.  The default value is <code>false</code>.</p>
    </attribute>

    <attribute name="xpoweredBy" required="false">
      <p>Set this attribute to <code>true</code> to cause Tomcat to advertise
      support for the Servlet specification using the header recommended in the
      specification.  The default value is <code>false</code>.</p>
    </attribute>

  </attributes>

  </subsection>

  <subsection name="Standard Implementation">

  <p>The standard HTTP connectors (NIO, NIO2 and APR/native) all support the
  following attributes in addition to the common Connector attributes listed
  above.</p>

  <attributes>

    <attribute name="acceptCount" required="false">
      <p>The maximum queue length for incoming connection requests when
      all possible request processing threads are in use.  Any requests
      received when the queue is full will be refused.  The default
      value is 100.</p>
    </attribute>

    <attribute name="acceptorThreadPriority" required="false">
      <p>The priority of the acceptor threads. The threads used to accept
      new connections. The default value is <code>5</code> (the value of the
      <code>java.lang.Thread.NORM_PRIORITY</code> constant). See the JavaDoc
      for the <code>java.lang.Thread</code> class for more details on what
      this priority means.</p>
    </attribute>

    <attribute name="address" required="false">
      <p>For servers with more than one IP address, this attribute specifies
      which address will be used for listening on the specified port. By
      default, the connector will listen all local addresses. Unless the JVM is
      configured otherwise using system properties, the Java based connectors
      (NIO, NIO2) will listen on both IPv4 and IPv6 addresses when configured
      with either <code>0.0.0.0</code> or <code>::</code>. The APR/native
      connector will only listen on IPv4 addresses if configured with
      <code>0.0.0.0</code> and will listen on IPv6 addresses (and optionally
      IPv4 addresses depending on the setting of <strong>ipv6v6only</strong>) if
      configured with <code>::</code>.</p>
    </attribute>

    <attribute name="allowHostHeaderMismatch" required="false">
      <p>By default Tomcat will reject requests that specify a host in the
      request line but specify a different host in the host header. This
      check can be disabled by setting this attribute to <code>true</code>. If
      not specified, the default is <code>false</code>.</p>
    </attribute>

    <attribute name="allowedTrailerHeaders" required="false">
      <p>By default Tomcat will ignore all trailer headers when processing
      chunked input. For a header to be processed, it must be added to this
      comma-separated list of header names.</p>
    </attribute>

    <attribute name="bindOnInit" required="false">
      <p>Controls when the socket used by the connector is bound. By default it
      is bound when the connector is initiated and unbound when the connector is
      destroyed. If set to <code>false</code>, the socket will be bound when the
      connector is started and unbound when it is stopped.</p>
    </attribute>

    <attribute name="clientCertProvider" required="false">
      <p>When client certificate information is presented in a form other than
      instances of <code>java.security.cert.X509Certificate</code> it needs to
      be converted before it can be used and this property controls which JSSE
      provider is used to perform the conversion. For example it is used with
      the <a href="ajp.html">AJP connectors</a>, the HTTP APR connector and
      with the <a href="valve.html#SSL_Authenticator_Valve">
      org.apache.catalina.valves.SSLValve</a>. If not specified, the default
      provider will be used.</p>
    </attribute>

    <attribute name="compressibleMimeType" required="false">
      <p>The value is a comma separated list of MIME types for which HTTP
      compression may be used.
      The default value is
      <code>
      text/html,text/xml,text/plain,text/css,text/javascript,application/javascript,application/json,application/xml
      </code>.
      </p>
    </attribute>

    <attribute name="compression" required="false">
      <p>The <strong>Connector</strong> may use HTTP/1.1 GZIP compression in
      an attempt to save server bandwidth. The acceptable values for the
      parameter is "off" (disable compression), "on" (allow compression, which
      causes text data to be compressed), "force" (forces compression in all
      cases), or a numerical integer value (which is equivalent to "on", but
      specifies the minimum amount of data before the output is compressed). If
      the content-length is not known and compression is set to "on" or more
      aggressive, the output will also be compressed. If not specified, this
      attribute is set to "off".</p>
      <p><em>Note</em>: There is a tradeoff between using compression (saving
      your bandwidth) and using the sendfile feature (saving your CPU cycles).
      If the connector supports the sendfile feature, e.g. the NIO connector,
      using sendfile will take precedence over compression. The symptoms will
      be that static files greater that 48 Kb will be sent uncompressed.
      You can turn off sendfile by setting <code>useSendfile</code> attribute
      of the connector, as documented below, or change the sendfile usage
      threshold in the configuration of the
      <a href="../default-servlet.html">DefaultServlet</a> in the default
      <code>conf/web.xml</code> or in the <code>web.xml</code> of your web
      application.
      </p>
    </attribute>

    <attribute name="compressionMinSize" required="false">
      <p>If <strong>compression</strong> is set to "on" then this attribute
      may be used to specify the minimum amount of data before the output is
      compressed. If not specified, this attribute is defaults to "2048".</p>
    </attribute>

    <attribute name="connectionLinger" required="false">
      <p>The number of seconds during which the sockets used by this
      <strong>Connector</strong> will linger when they are closed. The default
      value is <code>-1</code> which disables socket linger.</p>
    </attribute>

    <attribute name="connectionTimeout" required="false">
      <p>The number of milliseconds this <strong>Connector</strong> will wait,
      after accepting a connection, for the request URI line to be
      presented. Use a value of -1 to indicate no (i.e. infinite) timeout.
      The default value is 60000 (i.e. 60 seconds) but note that the standard
      server.xml that ships with Tomcat sets this to 20000 (i.e. 20 seconds).
      Unless <strong>disableUploadTimeout</strong> is set to <code>false</code>,
      this timeout will also be used when reading the request body (if any).</p>
    </attribute>

    <attribute name="connectionUploadTimeout" required="false">
      <p>Specifies the timeout, in milliseconds, to use while a data upload is
      in progress. This only takes effect if
      <strong>disableUploadTimeout</strong> is set to <code>false</code>.
      </p>
    </attribute>

    <attribute name="disableUploadTimeout" required="false">
      <p>This flag allows the servlet container to use a different, usually
      longer connection timeout during data upload. If not specified, this
      attribute is set to <code>true</code> which disables this longer timeout.
      </p>
    </attribute>

    <attribute name="executor" required="false">
      <p>A reference to the name in an <a href="executor.html">Executor</a>
      element. If this attribute is set, and the named executor exists, the
      connector will use the executor, and all the other thread attributes will
      be ignored. Note that if a shared executor is not specified for a
      connector then the connector will use a private, internal executor to
      provide the thread pool.</p>
    </attribute>

    <attribute name="executorTerminationTimeoutMillis" required="false">
      <p>The time that the private internal executor will wait for request
      processing threads to terminate before continuing with the process of
      stopping the connector. If not set, the default is  <code>5000</code> (5
      seconds).</p>
    </attribute>

    <attribute name="keepAliveTimeout" required="false">
      <p>The number of milliseconds this <strong>Connector</strong> will wait
      for another HTTP request before closing the connection. The default value
      is to use the value that has been set for the
      <strong>connectionTimeout</strong> attribute.
      Use a value of -1 to indicate no (i.e. infinite) timeout.</p>
    </attribute>

    <attribute name="maxConnections" required="false">
      <p>The maximum number of connections that the server will accept and
      process at any given time. When this number has been reached, the server
      will accept, but not process, one further connection. This additional
      connection be blocked until the number of connections being processed
      falls below <strong>maxConnections</strong> at which point the server will
      start accepting and processing new connections again. Note that once the
      limit has been reached, the operating system may still accept connections
      based on the <code>acceptCount</code> setting. The default value
      is <code>8192</code>.</p>
      <p>For NIO/NIO2 only, setting the value to -1, will disable the
      maxConnections feature and connections will not be counted.</p>
    </attribute>

    <attribute name="maxCookieCount" required="false">
      <p>The maximum number of cookies that are permitted for a request. A value
      of less than zero means no limit. If not specified, a default value of 200
      will be used.</p>
    </attribute>

    <attribute name="maxExtensionSize" required="false">
      <p>Limits the total length of chunk extensions in chunked HTTP requests.
      If the value is <code>-1</code>, no limit will be imposed. If not
      specified, the default value of <code>8192</code> will be used.</p>
    </attribute>

    <attribute name="maxHttpHeaderSize" required="false">
      <p>The maximum size of the request and response HTTP header, specified
      in bytes. If not specified, this attribute is set to 8192 (8 KB).</p>
    </attribute>

    <attribute name="maxKeepAliveRequests" required="false">
      <p>The maximum number of HTTP requests which can be pipelined until
      the connection is closed by the server. Setting this attribute to 1 will
      disable HTTP/1.0 keep-alive, as well as HTTP/1.1 keep-alive and
      pipelining. Setting this to -1 will allow an unlimited amount of
      pipelined or keep-alive HTTP requests.
      If not specified, this attribute is set to 100.</p>
    </attribute>

    <attribute name="maxSwallowSize" required="false">
      <p>The maximum number of request body bytes (excluding transfer encoding
      overhead) that will be swallowed by Tomcat for an aborted upload. An
      aborted upload is when Tomcat knows that the request body is going to be
      ignored but the client still sends it. If Tomcat does not swallow the body
      the client is unlikely to see the response. If not specified the default
      of 2097152 (2 megabytes) will be used. A value of less than zero indicates
      that no limit should be enforced.</p>
    </attribute>

    <attribute name="maxThreads" required="false">
      <p>The maximum number of request processing threads to be created
      by this <strong>Connector</strong>, which therefore determines the
      maximum number of simultaneous requests that can be handled.  If
      not specified, this attribute is set to 200. If an executor is associated
      with this connector, this attribute is ignored as the connector will
      execute tasks using the executor rather than an internal thread pool. Note
      that if an executor is configured any value set for this attribute will be
      recorded correctly but it will be reported (e.g. via JMX) as
      <code>-1</code> to make clear that it is not used.</p>
    </attribute>

    <attribute name="maxTrailerSize" required="false">
      <p>Limits the total length of trailing headers in the last chunk of
      a chunked HTTP request. If the value is <code>-1</code>, no limit will be
      imposed. If not specified, the default value of <code>8192</code> will be
      used.</p>
    </attribute>

    <attribute name="minSpareThreads" required="false">
      <p>The minimum number of threads always kept running.  This includes both
      active and idle threads. If not specified, the default of <code>10</code>
      is used. If an executor is associated with this connector, this attribute
      is ignored as the connector will execute tasks using the executor rather
      than an internal thread pool. Note that if an executor is configured any
      value set for this attribute will be recorded correctly but it will be
      reported (e.g. via JMX) as <code>-1</code> to make clear that it is not
      used.</p>
    </attribute>

    <attribute name="noCompressionStrongETag" required="false">
      <p>This flag configures whether resources with a stong ETag will be
      considered for compression. If <code>true</code>, resources with a strong
      ETag will not be compressed. The default value is <code>true</code>.</p>
      <p>This attribute is deprecated. It will be removed in Tomcat 10 onwards
      where it will be hard-coded to <code>true</code>.</p>
    </attribute>

    <attribute name="noCompressionUserAgents" required="false">
      <p>The value is a regular expression (using <code>java.util.regex</code>)
      matching the <code>user-agent</code> header of HTTP clients for which
      compression should not be used,
      because these clients, although they do advertise support for the
      feature, have a broken implementation.
      The default value is an empty String (regexp matching disabled).</p>
    </attribute>

    <attribute name="processorCache" required="false">
      <p>The protocol handler caches Processor objects to speed up performance.
      This setting dictates how many of these objects get cached.
      <code>-1</code> means unlimited, default is <code>200</code>. If not using
      Servlet 3.0 asynchronous processing, a good default is to use the same as
      the maxThreads setting. If using Servlet 3.0 asynchronous processing, a
      good default is to use the larger of maxThreads and the maximum number of
      expected concurrent requests (synchronous and asynchronous).</p>
    </attribute>

    <attribute name="rejectIllegalHeader" required="false">
      <p>If an HTTP request is received that contains an illegal header name or
      value (e.g. the header name is not a token) this setting determines if the
      request will be rejected with a 400 response (<code>true</code>) or if the
      illegal header be ignored (<code>false</code>). The default value is
      <code>true</code> which will cause the request to be rejected.</p>
    </attribute>

    <attribute name="relaxedPathChars" required="false">
      <p>The <a href="https://tools.ietf.org/rfc/rfc7230.txt">HTTP/1.1
      specification</a> requires that certain characters are %nn encoded when
      used in URI paths. Unfortunately, many user agents including all the major
      browsers are not compliant with this specification and use these
      characters in unencoded form. To prevent Tomcat rejecting such requests,
      this attribute may be used to specify the additional characters to allow.
      If not specified, no additional characters will be allowed. The value may
      be any combination of the following characters:
      <code>&quot; &lt; &gt; [ \ ] ^ ` { | }</code> . Any other characters
      present in the value will be ignored.</p>
    </attribute>

    <attribute name="relaxedQueryChars" required="false">
      <p>The <a href="https://tools.ietf.org/rfc/rfc7230.txt">HTTP/1.1
      specification</a> requires that certain characters are %nn encoded when
      used in URI query strings. Unfortunately, many user agents including all
      the major browsers are not compliant with this specification and use these
      characters in unencoded form. To prevent Tomcat rejecting such requests,
      this attribute may be used to specify the additional characters to allow.
      If not specified, no additional characters will be allowed. The value may
      be any combination of the following characters:
      <code>&quot; &lt; &gt; [ \ ] ^ ` { | }</code> . Any other characters
      present in the value will be ignored.</p>
    </attribute>

    <attribute name="restrictedUserAgents" required="false">
      <p>The value is a regular expression (using <code>java.util.regex</code>)
      matching the <code>user-agent</code> header of HTTP clients for which
      HTTP/1.1 or HTTP/1.0 keep alive should not be used, even if the clients
      advertise support for these features.
      The default value is an empty String (regexp matching disabled).</p>
    </attribute>

    <attribute name="server" required="false">
      <p>Overrides the Server header for the http response. If set, the value
      for this attribute overrides any Server header set by a web application.
      If not set, any value specified by the application is used. If the
      application does not specify a value then no Server header is set.</p>
    </attribute>

    <attribute name="serverRemoveAppProvidedValues" required="false">
      <p>If <code>true</code>, any Server header set by a web
      application will be removed. Note that if <strong>server</strong> is set,
      this attribute is effectively ignored. If not set, the default value of
      <code>false</code> will be used.</p>
    </attribute>

    <attribute name="SSLEnabled" required="false">
      <p>Use this attribute to enable SSL traffic on a connector.
      To turn on SSL handshake/encryption/decryption on a connector
      set this value to <code>true</code>.
      The default value is <code>false</code>.
      When turning this value <code>true</code> you will want to set the
      <code>scheme</code> and the <code>secure</code> attributes as well
      to pass the correct <code>request.getScheme()</code> and
      <code>request.isSecure()</code> values to the servlets
      See <a href="#SSL_Support">SSL Support</a> for more information.
      </p>
    </attribute>

    <attribute name="tcpNoDelay" required="false">
      <p>If set to <code>true</code>, the TCP_NO_DELAY option will be
      set on the server socket, which improves performance under most
      circumstances.  This is set to <code>true</code> by default.</p>
    </attribute>

    <attribute name="threadPriority" required="false">
      <p>The priority of the request processing threads within the JVM.
      The default value is <code>5</code> (the value of the
      <code>java.lang.Thread.NORM_PRIORITY</code> constant). See the JavaDoc
      for the <code>java.lang.Thread</code> class for more details on what
      this priority means. If an executor is associated
      with this connector, this attribute is ignored as the connector will
      execute tasks using the executor rather than an internal thread pool. Note
      that if an executor is configured any value set for this attribute will be
      recorded correctly but it will be reported (e.g. via JMX) as
      <code>-1</code> to make clear that it is not used.</p>
    </attribute>

    <attribute name="throwOnFailure" required="false">
      <p>If the Connector experiences an Exception during a Lifecycle transition
      should the Exception be rethrown or logged? If not specified, the default
      of <code>false</code> will be used. Note that the default can be changed
      by the <code>org.apache.catalina.startup.EXIT_ON_INIT_FAILURE</code>
      system property.</p>
    </attribute>

    <attribute name="useAsyncIO" required="false">
      <p>(bool) Use this attribute to enable or disable usage of the
      asynchronous IO API. The default value is <code>true</code> except when
      using the APR connector due to low performance.</p>
    </attribute>

    <attribute name="useKeepAliveResponseHeader" required="false">
      <p>(bool) Use this attribute to enable or disable the addition of the
      <code>Keep-Alive</code> HTTP response header as described in
      <a href="https://tools.ietf.org/html/draft-thomson-hybi-http-timeout-03">this
      Internet-Draft</a>. The default value is <code>true</code>.</p>
    </attribute>

  </attributes>

  </subsection>

  <subsection name="Java TCP socket attributes">

    <p>The NIO and NIO2 implementation support the following Java TCP
    socket attributes in addition to the common Connector and HTTP attributes
    listed above.</p>

    <attributes>
      <attribute name="socket.rxBufSize" required="false">
        <p>(int)The socket receive buffer (SO_RCVBUF) size in bytes. JVM default
        used if not set.</p>
      </attribute>
      <attribute name="socket.txBufSize" required="false">
        <p>(int)The socket send buffer (SO_SNDBUF) size in bytes. JVM default
        used if not set. Care should be taken if explicitly setting this value.
        Very poor performance has been observed on some JVMs with values less
        than ~8k.</p>
      </attribute>
      <attribute name="socket.tcpNoDelay" required="false">
        <p>(bool)This is equivalent to standard attribute
        <strong>tcpNoDelay</strong>.</p>
      </attribute>
      <attribute name="socket.soKeepAlive" required="false">
        <p>(bool)Boolean value for the socket's keep alive setting
        (SO_KEEPALIVE). JVM default used if not set.</p>
      </attribute>
      <attribute name="socket.ooBInline" required="false">
        <p>(bool)Boolean value for the socket OOBINLINE setting. JVM default
        used if not set.</p>
      </attribute>
      <attribute name="socket.soReuseAddress" required="false">
        <p>(bool)Boolean value for the sockets reuse address option
        (SO_REUSEADDR). JVM default used if not set.</p>
      </attribute>
      <attribute name="socket.soLingerOn" required="false">
        <p>(bool)Boolean value for the sockets so linger option (SO_LINGER).
        A value for the standard attribute <strong>connectionLinger</strong>
        that is &gt;=0 is equivalent to setting this to <code>true</code>.
        A value for the standard attribute <strong>connectionLinger</strong>
        that is &lt;0 is equivalent to setting this to <code>false</code>.
        Both this attribute and <code>soLingerTime</code> must be set else the
        JVM defaults will be used for both.</p>
      </attribute>
      <attribute name="socket.soLingerTime" required="false">
        <p>(int)Value in seconds for the sockets so linger option (SO_LINGER).
        This is equivalent to standard attribute
        <strong>connectionLinger</strong>.
        Both this attribute and <code>soLingerOn</code> must be set else the
        JVM defaults will be used for both.</p>
      </attribute>
      <attribute name="socket.soTimeout" required="false">
        <p>This is equivalent to standard attribute
        <strong>connectionTimeout</strong>.</p>
      </attribute>
      <attribute name="socket.performanceConnectionTime" required="false">
        <p>(int)The first value for the performance settings. See
        <a href="http://docs.oracle.com/javase/7/docs/api/java/net/Socket.html#setPerformancePreferences(int,%20int,%20int)">Socket Performance Options</a>.
        All three performance attributes must be set else the JVM defaults will
        be used for all three.</p>
      </attribute>
      <attribute name="socket.performanceLatency" required="false">
        <p>(int)The second value for the performance settings. See
        <a href="http://docs.oracle.com/javase/7/docs/api/java/net/Socket.html#setPerformancePreferences(int,%20int,%20int)">Socket Performance Options</a>.
        All three performance attributes must be set else the JVM defaults will
        be used for all three.</p>
      </attribute>
      <attribute name="socket.performanceBandwidth" required="false">
        <p>(int)The third value for the performance settings. See
        <a href="http://docs.oracle.com/javase/7/docs/api/java/net/Socket.html#setPerformancePreferences(int,%20int,%20int)">Socket Performance Options</a>.
        All three performance attributes must be set else the JVM defaults will
        be used for all three.</p>
      </attribute>
      <attribute name="socket.unlockTimeout" required="false">
        <p>(int) The timeout for a socket unlock. When a connector is stopped, it will try to release the acceptor thread by opening a connector to itself.
           The default value is <code>250</code> and the value is in milliseconds</p>
      </attribute>
    </attributes>
  </subsection>

  <subsection name="NIO specific configuration">

    <p>The following attributes are specific to the NIO connector.</p>

    <attributes>

      <attribute name="pollerThreadPriority" required="false">
        <p>(int)The priority of the poller threads.
        The default value is <code>5</code> (the value of the
        <code>java.lang.Thread.NORM_PRIORITY</code> constant). See the JavaDoc
        for the <code>java.lang.Thread</code> class for more details on what
        this priority means.</p>
      </attribute>

      <attribute name="selectorTimeout" required="false">
        <p>(int)The time in milliseconds to timeout on a select() for the
        poller. This value is important, since connection clean up is done on
        the same thread, so do not set this value to an extremely high one. The
        default value is <code>1000</code> milliseconds.</p>
      </attribute>

      <attribute name="useSendfile" required="false">
        <p>(bool)Use this attribute to enable or disable sendfile capability.
        The default value is <code>true</code>. Note that the use of sendfile
        will disable any compression that Tomcat may otherwise have performed on
        the response.</p>
      </attribute>

      <attribute name="socket.directBuffer" required="false">
        <p>(bool)Boolean value, whether to use direct ByteBuffers or java mapped
        ByteBuffers. If <code>true</code> then
        <code>java.nio.ByteBuffer.allocateDirect()</code> is used to allocate
        the buffers, if <code>false</code> then
        <code>java.nio.ByteBuffer.allocate()</code> is used. The default value
        is <code>false</code>.<br/>
        When you are using direct buffers, make sure you allocate the
        appropriate amount of memory for the direct memory space. On Sun's JDK
        that would be something like <code>-XX:MaxDirectMemorySize=256m</code>.
        </p>
      </attribute>

      <attribute name="socket.directSslBuffer" required="false">
        <p>(bool)Boolean value, whether to use direct ByteBuffers or java mapped
        ByteBuffers for the SSL buffers. If <code>true</code> then
        <code>java.nio.ByteBuffer.allocateDirect()</code> is used to allocate
        the buffers, if <code>false</code> then
        <code>java.nio.ByteBuffer.allocate()</code> is used. The default value
        is <code>false</code>.<br/>
        When you are using direct buffers, make sure you allocate the
        appropriate amount of memory for the direct memory space. On Oracle's JDK
        that would be something like <code>-XX:MaxDirectMemorySize=256m</code>.
        </p>
      </attribute>

      <attribute name="socket.appReadBufSize" required="false">
        <p>(int)Each connection that is opened up in Tomcat get associated with
        a read ByteBuffer. This attribute controls the size of this buffer. By
        default this read buffer is sized at <code>8192</code> bytes. For lower
        concurrency, you can increase this to buffer more data. For an extreme
        amount of keep alive connections, decrease this number or increase your
        heap size.</p>
      </attribute>

      <attribute name="socket.appWriteBufSize" required="false">
        <p>(int)Each connection that is opened up in Tomcat get associated with
        a write ByteBuffer. This attribute controls the size of this buffer. By
        default this write buffer is sized at <code>8192</code> bytes. For low
        concurrency you can increase this to buffer more response data. For an
        extreme amount of keep alive connections, decrease this number or
        increase your heap size.<br/>
        The default value here is pretty low, you should up it if you are not
        dealing with tens of thousands concurrent connections.</p>
      </attribute>

      <attribute name="socket.bufferPool" required="false">
        <p>(int)The NIOx connector uses a class called NioXChannel that holds
        elements linked to a socket. To reduce garbage collection, the NIOx
        connector caches these channel objects. This value specifies the size of
        this cache. The default value is <code>-2</code>. Special values are
        <code>-1</code> for unlimited cache, <code>0</code> for no cache,
        and <code>-2</code> for a value computed using the bufferPoolSize
        attribute.</p>
      </attribute>

      <attribute name="socket.bufferPoolSize" required="false">
        <p>(int)The NioXChannel pool can also be size based, not used object
        based. If bufferPool is not -2, then this value will not be used.<br/>
        The value is in bytes except for special values. Special values are
        <code>-1</code> for unlimited cache, <code>0</code> for no cache,
        and <code>-2</code> for a value computed as follows:<br/>
        NioXChannel
        <code>buffer size = read buffer size + write buffer size</code><br/>
        SecureNioXChannel <code>buffer size = application read buffer size +
        application write buffer size + twice the max SNI parse size</code>.
        If the maximum memory as reported by the runtime is greater than
        1GB, then the pool size value is the memory divided by the buffer
        size. Otherwise, it will be 0.
        </p>
      </attribute>

      <attribute name="socket.processorCache" required="false">
        <p>(int)Tomcat will cache SocketProcessor objects to reduce garbage
        collection. The integer value specifies how many objects to keep in the
        cache at most. The default is <code>0</code>. Special values are
        <code>-1</code> for unlimited cache and <code>0</code> for no cache.</p>
      </attribute>

      <attribute name="socket.eventCache" required="false">
        <p>(int)Tomcat will cache PollerEvent objects to reduce garbage
        collection. The integer value specifies how many objects to keep in the
        cache at most. The default is <code>0</code>. Special values are
        <code>-1</code> for unlimited cache and <code>0</code> for no cache.</p>
      </attribute>

      <attribute name="useInheritedChannel" required="false">
        <p>(bool)Defines if this connector should inherit an inetd/systemd network socket.
        Only one connector can inherit a network socket. This can option can be
        used to automatcially start Tomcat once a connection request is made to
        the systemd super daemon's port.
        The default value is <code>false</code>. See the JavaDoc
        for the <code>java.nio.channels.spi.SelectorProvider</code> class for
        more details.</p>
      </attribute>

    </attributes>
  </subsection>

  <subsection name="NIO2 specific configuration">

    <p>The following attributes are specific to the NIO2 connector.</p>

    <attributes>

      <attribute name="useSendfile" required="false">
        <p>(bool)Use this attribute to enable or disable sendfile capability.
        The default value is <code>true</code>. Note that the use of sendfile
        will disable any compression that Tomcat may otherwise have performed on
        the response.</p>
      </attribute>

      <attribute name="socket.directBuffer" required="false">
        <p>(bool)Boolean value, whether to use direct ByteBuffers or java mapped
        ByteBuffers. If <code>true</code> then
        <code>java.nio.ByteBuffer.allocateDirect()</code> is used to allocate
        the buffers, if <code>false</code> then
        <code>java.nio.ByteBuffer.allocate()</code> is used. The default value
        is <code>false</code>.<br/>
        When you are using direct buffers, make sure you allocate the
        appropriate amount of memory for the direct memory space. On Sun's JDK
        that would be something like <code>-XX:MaxDirectMemorySize=256m</code>.
        </p>
      </attribute>

      <attribute name="socket.directSslBuffer" required="false">
        <p>(bool)Boolean value, whether to use direct ByteBuffers or java mapped
        ByteBuffers for the SSL buffers. If <code>true</code> then
        <code>java.nio.ByteBuffer.allocateDirect()</code> is used to allocate
        the buffers, if <code>false</code> then
        <code>java.nio.ByteBuffer.allocate()</code> is used. The default value
        is <code>false</code>.<br/>
        When you are using direct buffers, make sure you allocate the
        appropriate amount of memory for the direct memory space. On Oracle's JDK
        that would be something like <code>-XX:MaxDirectMemorySize=256m</code>.
        </p>
      </attribute>

      <attribute name="socket.appReadBufSize" required="false">
        <p>(int)Each connection that is opened up in Tomcat get associated with
        a read ByteBuffer. This attribute controls the size of this buffer. By
        default this read buffer is sized at <code>8192</code> bytes. For lower
        concurrency, you can increase this to buffer more data. For an extreme
        amount of keep alive connections, decrease this number or increase your
        heap size.</p>
      </attribute>

      <attribute name="socket.appWriteBufSize" required="false">
        <p>(int)Each connection that is opened up in Tomcat get associated with
        a write ByteBuffer. This attribute controls the size of this buffer. By
        default this write buffer is sized at <code>8192</code> bytes. For low
        concurrency you can increase this to buffer more response data. For an
        extreme amount of keep alive connections, decrease this number or
        increase your heap size.<br/>
        The default value here is pretty low, you should up it if you are not
        dealing with tens of thousands concurrent connections.</p>
      </attribute>

      <attribute name="socket.bufferPool" required="false">
        <p>(int)The NIO2 connector uses a class called Nio2Channel that holds
        elements linked to a socket. To reduce garbage collection, the NIO2
        connector caches these channel objects. This value specifies the size of
        this cache. The default value is <code>500</code>, and represents that
        the cache will hold 500 Nio2Channel objects. Other values are
        <code>-1</code> for unlimited cache and <code>0</code> for no cache.</p>
      </attribute>

      <attribute name="socket.processorCache" required="false">
        <p>(int)Tomcat will cache SocketProcessor objects to reduce garbage
        collection. The integer value specifies how many objects to keep in the
        cache at most. The default is <code>500</code>. Other values are
        <code>-1</code> for unlimited cache and <code>0</code> for no cache.</p>
      </attribute>

    </attributes>
  </subsection>

  <subsection name="APR/native specific configuration">

    <p>The following attributes are specific to the APR/native connector.</p>

    <attributes>

      <attribute name="deferAccept" required="false">
        <p>Sets the <code>TCP_DEFER_ACCEPT</code> flag on the listening socket
        for this connector. The default value is <code>true</code> where
        <code>TCP_DEFER_ACCEPT</code> is supported by the operating system,
        otherwise it is <code>false</code>.</p>
      </attribute>

      <attribute name="ipv6v6only" required="false">
        <p>If listening on an IPv6 address on a dual stack system, should the
        connector only listen on the IPv6 address? If not specified the default
        is <code>false</code> and the connector will listen on the IPv6 address
        and the equivalent IPv4 address if present.</p>
      </attribute>

      <attribute name="pollerThreadCount" required="false">
        <p>Number of threads used to poll kept alive connections. On Windows the
        default is chosen so that the sockets managed by each thread is
        less than 1024. For Linux the default is 1. Changing the default on
        Windows is likely to have a negative performance impact.</p>
      </attribute>

      <attribute name="pollTime" required="false">
        <p>Duration of a poll call in microseconds. Lowering this value will
        slightly decrease latency of connections being kept alive in some cases,
        but will use more CPU as more poll calls are being made. The default
        value is 2000 (2ms).</p>
      </attribute>

      <attribute name="sendfileSize" required="false">
        <p>Amount of sockets that the poller responsible for sending static
        files asynchronously can hold at a given time. Extra connections will be
        closed right away without any data being sent (resulting in a zero
        length file on the client side). Note that in most cases, sendfile is a
        call that will return right away (being taken care of "synchronously" by
        the kernel), and the sendfile poller will not be used, so the amount of
        static files which can be sent concurrently is much larger than the
        specified amount. The default value is 1024.</p>
      </attribute>

      <attribute name="threadPriority" required="false">
        <p>(int)The priority of the acceptor and poller threads.
        The default value is <code>5</code> (the value of the
        <code>java.lang.Thread.NORM_PRIORITY</code> constant). See the JavaDoc
        for the <code>java.lang.Thread</code> class for more details on what
        this priority means.</p>
      </attribute>

      <attribute name="useSendfile" required="false">
        <p>(bool)Use this attribute to enable or disable sendfile capability.
        The default value is <code>true</code>. Note that the use of sendfile
        will disable any compression that Tomcat may otherwise have performed on
        the response.</p>
      </attribute>

    </attributes>

  </subsection>

</section>


<section name="Nested Components">

  <p>First implemented in Tomcat 9 and back-ported to 8.5, Tomcat now supports
  Server Name Indication (SNI). This allows multiple SSL configurations to be
  associated with a single secure connector with the configuration used for any
  given connection determined by the host name requested by the client. To
  facilitate this, the <strong>SSLHostConfig</strong> element was added which
  can be used to define one of these configurations. Any number of
  <strong>SSLHostConfig</strong> may be nested in a <strong>Connector</strong>.
  At the same time, support was added for multiple certificates to be associated
  with a single <strong>SSLHostConfig</strong>. Each SSL certificate is
  therefore configured in a <strong>Certificate</strong> element with in an
  <strong>SSLHostConfig</strong>. For further information, see the SSL Support
  section below.</p>

</section>


<section name="Special Features">


  <subsection name="HTTP/1.1 and HTTP/1.0 Support">

  <p>This <strong>Connector</strong> supports all of the required features
  of the HTTP/1.1 protocol, as described in RFCs 7230-7235, including persistent
  connections, pipelining, expectations and chunked encoding.  If the client
  supports only HTTP/1.0 or HTTP/0.9, the
  <strong>Connector</strong> will gracefully fall back to supporting this
  protocol as well.  No special configuration is required to enable this
  support. The <strong>Connector</strong> also supports HTTP/1.0
  keep-alive.</p>

  <p>RFC 7230 requires that HTTP servers always begin their responses with
  the highest HTTP version that they claim to support.  Therefore, this
  <strong>Connector</strong> will always return <code>HTTP/1.1</code> at
  the beginning of its responses.</p>

  </subsection>

  <subsection name="HTTP/2 Support">

  <p>HTTP/2 is support is provided for TLS (h2), non-TLS via HTTP upgrade (h2c)
     and direct HTTP/2 (h2c) connections. To enable HTTP/2 support for an HTTP
     connector the following <strong>UpgradeProtocol</strong> element must be
     nested within the <strong>Connector</strong> with a
     <strong>className</strong> attribute of
     <code>org.apache.coyote.http2.Http2Protocol</code>.</p>

<source><![CDATA[<Connector ... >
  <UpgradeProtocol className="org.apache.coyote.http2.Http2Protocol" />
</Connector>]]></source>

  <p>Because Java 8's TLS implementation does not support ALPN (which is
     required for HTTP/2 over TLS), you must be using an OpenSSL based TLS
     implementation to enable HTTP/2 support. See the
     <code>sslImplementationName</code> attribute of the
     <strong>Connector</strong>.</p>

  <p>Additional configuration attributes are available. See the
  <a href="http2.html">HTTP/2 Upgrade Protocol</a> documentation for details.</p>

  </subsection>

  <subsection name="Proxy Support">

  <p>The <code>proxyName</code> and <code>proxyPort</code> attributes can
  be used when Tomcat is run behind a proxy server.  These attributes
  modify the values returned to web applications that call the
  <code>request.getServerName()</code> and <code>request.getServerPort()</code>
  methods, which are often used to construct absolute URLs for redirects.
  Without configuring these attributes, the values returned would reflect
  the server name and port on which the connection from the proxy server
  was received, rather than the server name and port to whom the client
  directed the original request.</p>

  <p>For more information, see the
  <a href="../proxy-howto.html">Proxy Support How-To</a>.</p>

  </subsection>


  <subsection name="SSL Support">

  <p>You can enable SSL support for a particular instance of this
  <strong>Connector</strong> by setting the <code>SSLEnabled</code> attribute to
  <code>true</code>.</p>

  <p>You will also need to set the <code>scheme</code> and <code>secure</code>
  attributes to the values <code>https</code> and <code>true</code>
  respectively, to pass correct information to the servlets.</p>

  <p>The NIO and NIO2 connectors use either the JSSE Java SSL implementation or
  an OpenSSL implementation, whereas the APR/native connector uses OpenSSL only.
  Prior to Tomcat 8.5, different configuration attributes were used for JSSE and
  OpenSSL. From Tomcat 8.5 onwards, and as far as possible, common configuration
  attributes are used for both JSSE and OpenSSL. Also if using the JSSE OpenSSL
  implementation, configuration can be set using either the JSSE or APR
  attributes (note: but not both types within the same configuration). This is
  to aid simpler switching between connector implementations for SSL
  connectors.</p>

  <p>Each secure connector must define at least one
  <strong>SSLHostConfig</strong>. The names of the
  <strong>SSLHostConfig</strong> elements must be unique and one of them must
  match the <code>defaultSSLHostConfigName</code> attribute of the
  <strong>Connector</strong>.</p>

  <p>Each <strong>SSLHostConfig</strong> must in turn define at least one
  <strong>Certificate</strong>. The types of the <strong>Certificate</strong>s
  must be unique.</p>

  <p>As of Tomcat 8.5, the majority of the SSL configuration attributes in the
  <strong>Connector</strong> are deprecated. If specified, they will be used to
  configure a <strong>SSLHostConfig</strong> and <strong>Certificate</strong>
  for the <code>defaultSSLHostConfigName</code>. Note that if an explicit
  <strong>SSLHostConfig</strong> element also exists for the
  <code>defaultSSLHostConfigName</code> then that will be treated as a configuration
  error. It is expected that Tomcat 10 will drop support for the SSL
  configuration attributes in the <strong>Connector</strong>.</p>

  <p>For more information, see the
  <a href="../ssl-howto.html">SSL Configuration How-To</a>.</p>

  </subsection>

  <subsection name="SSL Support - SSLHostConfig">

  <p></p>

  <attributes>

    <attribute name="certificateRevocationListFile" required="false">
      <p>Name of the file that contains the concatenated certificate revocation
      lists for the certificate authorities. The format is PEM-encoded. If not
      defined, client certificates will not be checked against a certificate
      revocation list (unless an OpenSSL based connector is used and
      <strong>certificateRevocationListPath</strong> is defined). Relative paths
      will be resolved against <code>$CATALINA_BASE</code>. JSSE based
      connectors may also specify a URL for this attribute.</p>
    </attribute>

    <attribute name="certificateRevocationListPath" required="false">
      <p>OpenSSL only.</p>
      <p>Name of the directory that contains the certificate revocation lists
      for the certificate authorities. The format is PEM-encoded. Relative paths
      will be resolved against <code>$CATALINA_BASE</code>.</p>
    </attribute>

    <attribute name="certificateVerification" required="false">
      <p>Set to <code>required</code> if you want the SSL stack to require a
      valid certificate chain from the client before accepting a connection.
      Set to <code>optional</code> if you want the SSL stack to request a client
      Certificate, but not fail if one isn't presented. Set to
      <code>optionalNoCA</code> if you want client certificates to be optional
      and you don't want Tomcat to check them against the list of trusted CAs.
      If the TLS provider doesn't support this option (OpenSSL does, JSSE does
      not) it is treated as if <code>optional</code> was specified. A
      <code>none</code> value (which is the default) will not require a
      certificate chain unless the client requests a resource protected by a
      security constraint that uses <code>CLIENT-CERT</code> authentication.</p>
    </attribute>

    <attribute name="certificateVerificationDepth" required="false">
      <p>The maximum number of intermediate certificates that will be allowed
      when validating client certificates. If not specified, the default value
      of 10 will be used.</p>
    </attribute>

    <attribute name="caCertificateFile" required="false">
      <p>OpenSSL only.</p>
      <p>Name of the file that contains the concatenated certificates for the
      trusted certificate authorities. The format is PEM-encoded.</p>
    </attribute>

    <attribute name="caCertificatePath" required="false">
      <p>OpenSSL only.</p>
      <p>Name of the directory that contains the certificates for the trusted
      certificate authorities. The format is PEM-encoded.</p>
    </attribute>

    <attribute name="ciphers" required="false">
      <p>The ciphers to enable using the OpenSSL syntax. (See the OpenSSL
      documentation for the list of ciphers supported and the syntax).
      Alternatively, a comma separated list of ciphers using the standard
      OpenSSL cipher names or the standard JSSE cipher names may be used.</p>
      <p>When converting from OpenSSL syntax to JSSE ciphers for JSSE based
      connectors, the behaviour of the OpenSSL syntax parsing is kept aligned
      with the behaviour of the OpenSSL 1.1.0 development branch.</p>
      <p>Only the ciphers that are supported by the SSL implementation will be
      used.</p>
      <p>If not specified, a default (using the OpenSSL notation) of
      <code>HIGH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!kRSA</code> will be
      used.</p>
      <p>Note that, by default, the order in which ciphers are defined is
      treated as an order of preference. See <code>honorCipherOrder</code>.</p>
    </attribute>

    <attribute name="disableCompression" required="false">
      <p>OpenSSL only.</p>
      <p>Configures if compression is disabled. The default is
      <code>true</code>. If the OpenSSL version used does not support disabling
      compression then the default for that OpenSSL version will be used.</p>
    </attribute>

    <attribute name="disableSessionTickets" required="false">
      <p>OpenSSL only.</p>
      <p>Disables use of TLS session tickets (RFC 5077) if set to
      <code>true</code>. Default is <code>false</code>. Note that when TLS
      session tickets are in use, the full peer certificate chain will only be
      available on the first connection. Subsequent connections (that use a
      ticket to estrablish the TLS session) will only have the peer certificate,
      not the full chain.</p>
    </attribute>

    <attribute name="honorCipherOrder" required="false">
      <p>Set to <code>true</code> to enforce the server's cipher order
      (from the <code>ciphers</code> setting) instead of allowing
      the client to choose the cipher. The default is <code>false</code>.</p>
    </attribute>

    <attribute name="hostName" required="false">
      <p>The name of the SSL Host. This should either be the fully qualified
      domain name (e.g. <code>tomcat.apache.org</code>) or a wild card domain
      name (e.g. <code>*.apache.org</code>). If not specified, the default value
      of <code>_default_</code> will be used.</p>
    </attribute>

    <attribute name="insecureRenegotiation" required="false">
      <p>OpenSSL only.</p>
      <p>Configures if insecure renegotiation is allowed. The default is
      <code>false</code>. If the OpenSSL version used does not support
      configuring if insecure renegotiation is allowed then the default for that
      OpenSSL version will be used.</p>
    </attribute>

    <attribute name="keyManagerAlgorithm" required="false">
      <p>JSSE only.</p>
      <p>The <code>KeyManager</code> algorithm to be used. This defaults to
      <code>KeyManagerFactory.getDefaultAlgorithm()</code> which returns
      <code>SunX509</code> for Sun JVMs. IBM JVMs return
      <code>IbmX509</code>. For other vendors, consult the JVM
      documentation for the default value.</p>
    </attribute>

    <attribute name="protocols" required="false">
      <p>The names of the protocols to support when communicating with clients.
      This should be a list of any combination of the following:
      </p>
      <ul><li>SSLv2Hello</li><li>SSLv3</li><li>TLSv1</li><li>TLSv1.1</li>
      <li>TLSv1.2</li><li>TLSv1.3</li><li>all</li></ul>
      <p>Each token in the list can be prefixed with a plus sign ("+")
      or a minus sign ("-"). A plus sign adds the protocol, a minus sign
      removes it form the current list. The list is built starting from
      an empty list.</p>
      <p>The token <code>all</code> is an alias for
      <code>SSLv2Hello,TLSv1,TLSv1.1,TLSv1.2,TLSv1.3</code>.</p>
      <p>Note that <code>TLSv1.3</code> is only supported for JSSE when using a
      JVM that implements <code>TLSv1.3</code>.</p>
      <p>Note that <code>SSLv2Hello</code> will be ignored for OpenSSL based
      secure connectors. If more than one protocol is specified for an OpenSSL
      based secure connector it will always support <code>SSLv2Hello</code>. If a
      single protocol is specified it will not support
      <code>SSLv2Hello</code>.</p>
      <p>Note that <code>SSLv2</code> and <code>SSLv3</code> are inherently
      unsafe.</p>
      <p>If not specified, the default value of <code>all</code> will be
      used.</p>
    </attribute>

    <attribute name="revocationEnabled" required="false">
      <p>JSSE only.</p>
      <p>Should the JSSE provider enable certificate revocation checks? If
      <strong>certificateRevocationListFile</strong> is set then this attribute
      is ignored and revocation checks are always enabled. This attribute is
      intended to enable revocation checks that have been configured for the
      current JSSE provider via other means. If not specified, a default of
      <code>false</code> is used.</p>
    </attribute>

    <attribute name="sessionCacheSize" required="false">
      <p>The number of SSL sessions to maintain in the session cache. Specify
      <code>-1</code> to use the implementation default. Values of zero and
      above are passed to the implementation. Zero is used to specify an
      unlimited cache size and is not recommended. If not specified, a default
      of <code>-1</code> is used.</p>
    </attribute>

    <attribute name="sessionTimeout" required="false">
      <p>The time, in seconds, after the creation of an SSL session that it will
      timeout. Specify <code>-1</code> to use the implementation default. Values
      of zero and above are passed to the implementation. Zero is used to
      specify an unlimited timeout and is not recommended. If not specified, a
      default of 86400 (24 hours) is used.</p>
    </attribute>

    <attribute name="sslProtocol" required="false">
      <p>JSSE only.</p>
      <p>The SSL protocol(s) to use (a single value may enable multiple
      protocols - see the JVM documentation for details). If not specified, the
      default is <code>TLS</code>. The permitted values may be obtained from the
      JVM documentation for the allowed values for algorithm when creating an
      <code>SSLContext</code> instance e.g.
      <a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#SSLContext">
      Oracle Java 7</a>. Note: There is overlap between this attribute and
      <code>protocols</code>.</p>
    </attribute>

    <attribute name="trustManagerClassName" required="false">
      <p>JSSE only.</p>
      <p>The name of a custom trust manager class to use to validate client
      certificates. The class must have a zero argument constructor and must
      also implement <code>javax.net.ssl.X509TrustManager</code>. If this
      attribute is set, the trust store attributes may be ignored.</p>
    </attribute>

    <attribute name="truststoreAlgorithm" required="false">
      <p>JSSE only.</p>
      <p>The algorithm to use for truststore. If not specified, the default
      value returned by
      <code>javax.net.ssl.TrustManagerFactory.getDefaultAlgorithm()</code> is
      used.</p>
    </attribute>

    <attribute name="truststoreFile" required="false">
      <p>JSSE only.</p>
      <p>The trust store file to use to validate client certificates. The
      default is the value of the <code>javax.net.ssl.trustStore</code> system
      property. If neither this attribute nor the default system property is
      set, no trust store will be configured. Relative paths
      will be resolved against <code>$CATALINA_BASE</code>. A URL may also be
      used for this attribute.</p>
    </attribute>

    <attribute name="truststorePassword" required="false">
      <p>JSSE only.</p>
      <p>The password to access the trust store. The default is the value of the
      <code>javax.net.ssl.trustStorePassword</code> system property. If that
      property is null, no trust store password will be configured. If an
      invalid trust store password is specified, a warning will be logged and an
      attempt will be made to access the trust store without a password which
      will skip validation of the trust store contents.</p>
    </attribute>

    <attribute name="truststoreProvider" required="false">
      <p>JSSE only.</p>
      <p>The name of the truststore provider to be used for the server
      certificate. The default is the value of the
      <code>javax.net.ssl.trustStoreProvider</code> system property. If
      that property is null, the value of <code>keystoreProvider</code> is used
      as the default. If neither this attribute, the default system property nor
      <code>keystoreProvider</code> is set, the list of registered providers is
      traversed in preference order and the first provider that supports the
      <code>truststoreType</code> is used.
      </p>
    </attribute>

    <attribute name="truststoreType" required="false">
      <p>JSSE only.</p>
      <p>The type of key store used for the trust store. The default is the
      value of the <code>javax.net.ssl.trustStoreType</code> system property. If
      that property is null, a single certificate has been configured for this
      TLS virtual host and that certificate has a <code>keystoreType</code> that
      is not <code>PKCS12</code> then the default will be the
      <code>keystoreType</code> of the single certificate. If none of these
      identify a default, the default will be <code>JKS</code>. See the notes on
      <a href="#Key_store_types">key store types</a> below.</p>
     </attribute>

  </attributes>

  </subsection>

  <subsection name="SSL Support - Certificate">

  <p></p>

  <attributes>

    <attribute name="certificateFile" required="true">
      <p>Name of the file that contains the server certificate. The format is
      PEM-encoded. Relative paths will be resolved against
      <code>$CATALINA_BASE</code>.</p>
      <p>In addition to the certificate, the file can also contain as optional
      elements DH parameters and/or an EC curve name for ephemeral keys, as
      generated by <code>openssl dhparam</code> and <code>openssl ecparam</code>,
      respectively. The output of the respective OpenSSL command can simply
      be concatenated to the certificate file.</p>
    </attribute>

    <attribute name="certificateChainFile" required="false">
      <p>Name of the file that contains the certificate chain associated with
      the server certificate used. The format is
      PEM-encoded. Relative paths will be resolved against
      <code>$CATALINA_BASE</code>.</p>
      <p>The certificate chain used for Tomcat should not include the server
      certificate as its first element.</p>
      <p>Note that when using more than one certificate for different types,
      they all must use the same certificate chain.</p>
    </attribute>

    <attribute name="certificateKeyAlias" required="false">
      <p>JSSE only.</p>
      <p>The alias used for the server key and certificate in the keystore. If
      not specified, the first key read from the keystore will be used. The
      order in which keys are read from the keystore is implementation
      dependent. It may not be the case that keys are read from the keystore in
      the same order as they were added. If more than one key is present in the
      keystore it is strongly recommended that a keyAlias is configured to
      ensure that the correct key is used.</p>
    </attribute>

    <attribute name="certificateKeyFile" required="false">
      <p>Name of the file that contains the server private key. The format is
      PEM-encoded. The default value is the value of
      <strong>certificateFile</strong> and in this case both certificate and
      private key have to be in this file (NOT RECOMMENDED). Relative paths will
      be resolved against <code>$CATALINA_BASE</code>.</p>
    </attribute>

    <attribute name="certificateKeyPassword" required="false">
      <p>The password used to access the private key associated with the server
      certificate from the specified file.</p>
      <p>If not specified, the default behaviour for JSSE is to use the
      <strong>certificateKeystorePassword</strong>. For OpenSSL the default
      behaviour is not to use a password.</p>
    </attribute>

    <attribute name="certificateKeystoreFile" required="false">
      <p>JSSE only.</p>
      <p>The pathname of the keystore file where you have stored the server
      certificate and key to be loaded. By default, the pathname is the file
      <code>.keystore</code> in the operating system home directory of the user
      that is running Tomcat. If your <code>keystoreType</code> doesn't need a
      file use <code>""</code> (empty string) or <code>NONE</code> for this
      parameter.  Relative paths will be resolved against
      <code>$CATALINA_BASE</code>.  A URI may also be used for this attribute.
      When using a domain keystore (<code>keystoreType</code> of
      <code>DKS</code>), this parameter should be the URI to the domain
      keystore.</p>
    </attribute>

    <attribute name="certificateKeystorePassword" required="false">
      <p>JSSE only.</p>
      <p>The password to use to access the keystore containing the server&apos;s
      private key and certificate. If not specified, a default of
      <code>changeit</code> will be used.</p>
    </attribute>

    <attribute name="certificateKeystoreProvider" required="false">
      <p>JSSE only.</p>
      <p>The name of the keystore provider to be used for the server
      certificate. If not specified, the value of the system property
      <code>javax.net.ssl.keyStoreProvider</code> is used. If neither this
      attribute nor the system property are set, the list of registered
      providers is traversed in preference order and the first provider that
      supports the <code>keystoreType</code> is used.
      </p>
    </attribute>

    <attribute name="certificateKeystoreType" required="false">
      <p>JSSE only.</p>
      <p>The type of keystore file to be used for the server certificate.
      If not specified, the value of the system property
      <code>javax.net.ssl.keyStoreType</code> is used. If neither this attribute
      nor the system property are set, a default value of "<code>JKS</code>". is
      used. See the notes on <a href="#Key_store_types">key store types</a>
      below.</p>
    </attribute>

    <attribute name="type" required="false">
      <p>The type of certificate. This is used to identify the ciphers that are
      compatible with the certificate. It must be one of <code>UNDEFINED</code>,
      <code>RSA</code>, <code>DSS</code> or <code>EC</code>. If only one
      <strong>Certificate</strong> is nested within a <code>SSLHostConfig</code>
      then this attribute is not required and will default to
      <code>UNDEFINED</code>. If multiple <strong>Certificate</strong>s are
      nested within a <code>SSLHostConfig</code> then this attribute is required
      and each <strong>Certificate</strong> must have a unique type.</p>
    </attribute>

  </attributes>

  </subsection>

  <subsection name="SSL Support - Connector - NIO and NIO2">

  <p>When APR/native is enabled, the connectors will default to using
  OpenSSL through JSSE, which may be more optimized than the JSSE Java
  implementation depending on the processor being used,
  and can be complemented with many commercial accelerator components.</p>

  <p>The following NIO and NIO2 SSL configuration attributes are not specific to
  a virtual host and, therefore, must be configured on the connector.</p>

  <attributes>

    <attribute name="sniParseLimit" required="false">
      <p>In order to implement SNI support, Tomcat has to parse the first TLS
      message received on a new TLS connection (the client hello) to extract the
      requested server name. The message needs to be buffered so it can then be
      passed to the JSSE implementation for normal TLS processing. In theory,
      this first message could be very large although in practice it is
      typically a few hundred bytes. This attribute sets the maximum message
      size that Tomcat will buffer. If a message exceeds this size, the
      connection will be configured as if no server name was indicated by the
      client. If not specified a default of <code>65536</code> (64k) will be
      used.</p>
    </attribute>

    <attribute name="sslImplementationName" required="false">
      <p>The class name of the SSL implementation to use. If not specified and
      the tomcat-native library is not installed, the
      default of <code>org.apache.tomcat.util.net.jsse.JSSEImplementation</code>
      will be used which wraps JVM&apos;s default JSSE provider. Note that the
      JVM can be configured to use a different JSSE provider as the default.
      Tomcat also bundles a special SSL implementation for JSSE that is backed
      by OpenSSL. To enable it, the native library should be enabled as if
      intending to use the APR connector, and Tomcat will automatically enable it
      and the default value of this attribute becomes
      <code>org.apache.tomcat.util.net.openssl.OpenSSLImplementation</code>.
      In that case, the attributes from either JSSE and OpenSSL
      configuration styles can be used, as long as the two types are not mixed
      (for example, it is not allowed to define use of a Java keystore and
      specify a separate pem private key using the OpenSSL attribute).</p>
    </attribute>

  </attributes>

  </subsection>

  <subsection name="Key store types">

    <p>In addition to the standard key store types (JKS and PKCS12), most Java
    runtimes support additional key store types such as Windows-ROOT,
    Windows-My, DKS as well as hardware security modules. Generally, to use
    these additional keystore types with a TLS Conector in Tomcat:</p>

    <ul>
      <li>Set the certificateKeystoreType and/or truststoreType Connector
          attribute (as appropriate) to the necessary type</li>
      <li>If a configuration file is required, set the certificateKeystoreFile
          and/or truststoreFile Connector attribute (as appropriate) to point to
          the file</li>
      <li>If no configuration file is required then you will almost certainly
          need to explicitly set the certificateKeystoreFile and/or
          truststoreFile Connector attribute (as appropriate) to the empty
          string ("")</li>
      <li>If a password is required, set the certificateKeystorePassword and/or
          truststorePassword Connector attribute (as appropriate) to the
          required password</li>
      <li>If no password is required then you will almost certainly need to
          explicitly set the certificateKeystorePassword and/or
          truststorePassword Connector attribute (as appropriate) to the empty
          string ("")</li>
    </ul>

    <p>Variations in key store implementations, combined with the key store
    manipulation Tomcat does in the background to allow interoperability between
    JSSE and OpenSSL configuration styles, means that some keystores may need
    slightly different configuration. Assitance is always available from the
    <a href="http://tomcat.apache.org/lists.html#tomcat-users">Apache Tomcat
    users mailing list</a>. We aim to document any key stores that vary from the
    above advice here. Currently there are none we are aware of.</p>

  </subsection>

  <subsection name="Connector Comparison">

    <p>Below is a small chart that shows how the connectors differ.</p>

    <table class="defaultTable" style="text-align: center;">
      <tr>
        <th />
        <th style="text-align: center;">Java Nio Connector<br />NIO</th>
        <th style="text-align: center;">Java Nio2 Connector<br />NIO2</th>
        <th style="text-align: center;">APR/native Connector<br />APR</th>
      </tr>
      <tr>
        <th>Classname</th>
        <td><code class="noHighlight">Http11NioProtocol</code></td>
        <td><code class="noHighlight">Http11Nio2Protocol</code></td>
        <td><code class="noHighlight">Http11AprProtocol</code></td>
      </tr>
      <tr>
        <th>Tomcat Version</th>
        <td>since 6.0.x</td>
        <td>since 8.0.x</td>
        <td>since 5.5.x</td>
      </tr>
      <tr>
        <th>Support Polling</th>
        <td>YES</td>
        <td>YES</td>
        <td>YES</td>
      </tr>
      <tr>
        <th>Polling Size</th>
        <td><code class="noHighlight">maxConnections</code></td>
        <td><code class="noHighlight">maxConnections</code></td>
        <td><code class="noHighlight">maxConnections</code></td>
      </tr>
      <tr>
        <th>Read Request Headers</th>
        <td>Non Blocking</td>
        <td>Non Blocking</td>
        <td>Non Blocking</td>
      </tr>
      <tr>
        <th>Read Request Body</th>
        <td>Blocking</td>
        <td>Blocking</td>
        <td>Blocking</td>
      </tr>
      <tr>
        <th>Write Response Headers and Body</th>
        <td>Blocking</td>
        <td>Blocking</td>
        <td>Blocking</td>
      </tr>
      <tr>
        <th>Wait for next Request</th>
        <td>Non Blocking</td>
        <td>Non Blocking</td>
        <td>Non Blocking</td>
      </tr>
      <tr>
        <th>SSL Support</th>
        <td>Java SSL or OpenSSL</td>
        <td>Java SSL or OpenSSL</td>
        <td>OpenSSL</td>
      </tr>
      <tr>
        <th>SSL Handshake</th>
        <td>Non blocking</td>
        <td>Non blocking</td>
        <td>Blocking</td>
      </tr>
      <tr>
        <th>Max Connections</th>
        <td><code class="noHighlight">maxConnections</code></td>
        <td><code class="noHighlight">maxConnections</code></td>
        <td><code class="noHighlight">maxConnections</code></td>
      </tr>
    </table>

  </subsection>
</section>


</body>

</document>
