The DocumentRoot should be specified without a trailing slash. For example: In. This directive controls whether the httpd may use memory-mapping if it needs to read the contents of a file during delivery.
This memory-mapping sometimes yields a performance improvement. But in some environments, it is better to disable the memory-mapping to prevent operational problems:. For server configurations that are vulnerable to these problems, you should disable memory-mapping of delivered files by specifying:. For NFS mounted files, this feature may be disabled explicitly for the offending files by specifying:. This directive controls whether httpd may use the sendfile support from the kernel to transmit file contents to the client.
By default, when the handling of a request requires no access to the data within a file -- for example, when delivering a static file -- Apache httpd uses sendfile to deliver the file contents without ever reading the file if the OS supports it. This sendfile mechanism avoids separate read and send operations, and buffer allocations.
But on some platforms or within some filesystems, it is better to disable this feature to avoid operational problems:. For server configurations that are not vulnerable to these problems, you may enable this feature by specifying:. For network mounted files, this feature may be disabled explicitly for the offending files by specifying:.
Please note that the per-directory and. Only global definition of EnableSendfile is taken into account by the module. If an error can be detected within the configuration, this directive can be used to generate a custom error message, and halt configuration parsing.
The typical use is for reporting required modules which are missing from the configuration. The first option is the default, while options are configured using the ErrorDocument directive, which is followed by the HTTP response code and a URL or a message.
Alternatively, a message can be provided to be displayed by the browser. Note that deciding whether the parameter is an URL, a path or a message is performed before any expression is parsed. Additionally, the special value default can be used to specify Apache httpd's simple hardcoded message.
While not required under normal circumstances, default will restore Apache httpd's simple hardcoded message for configurations that would otherwise inherit an existing ErrorDocument. This has several implications, the most important being that the client will not receive the original error status code, but instead will receive a redirect status code. This in turn can confuse web robots and other clients which try to determine if a URL is valid using the status code.
In addition, if you use a remote URL in an ErrorDocument , the client will not know to prompt the user for a password since it will not receive the status code. Therefore, if you use an ErrorDocument directive, then it must refer to a local document.
Microsoft Internet Explorer MSIE will by default ignore server-generated error messages when they are "too small" and substitute its own "friendly" error messages. The size threshold varies depending on the type of error, but in general, if you make your error document greater than bytes, then MSIE will show the server-generated error rather than masking it.
More information is available in Microsoft Knowledge Base article Q Although most error messages can be overridden, there are certain circumstances where the internal messages are used regardless of the setting of ErrorDocument.
In particular, if a malformed request is detected, normal request processing will be immediately halted and the internal error message returned. This is necessary to guard against security problems caused by bad requests. If you don't enable ProxyErrorOverride, Apache httpd will not generate custom error documents for proxied content.
The ErrorLog directive sets the name of the file to which the server will log any errors it encounters. If the file-path is not absolute then it is assumed to be relative to the ServerRoot. If the file-path begins with a pipe character " " then it is assumed to be a command to spawn to handle the error log. Using syslog instead of a filename enables logging via syslogd 8 if the system supports it. The default is to use syslog facility local7 , but you can override this by using the syslog: facility syntax where facility can be one of the names usually documented in syslog 1.
The facility is effectively global, and if it is changed in individual virtual hosts, the final facility specified affects the entire server. Same rules apply for the syslog tag, which by default uses the Apache binary name, httpd in most cases. You can also override this by using the syslog:: tag syntax. SECURITY: See the security tips document for details on why your security could be compromised if the directory where log files are stored is writable by anyone other than the user that starts the server.
When entering a file path on non-Unix platforms, care should be taken to make sure that only forward slashes are used even though the platform may allow the use of back slashes. In general it is a good idea to always use forward slashes throughout the configuration files. ErrorLogFormat allows to specify what supplementary information is logged in the error log in addition to the actual log message.
Specifying connection or request as first parameter allows to specify additional formats, causing additional information to be logged when the first message is logged for a specific connection or request, respectively. If a connection or request is processed without causing any log message, the additional information is not logged either. It can happen that some format string items do not produce output. For example, the Referer header is only present if the log message is associated to a request and the log message happens at a time when the Referer header has already been read from the client.
If no output is produced, the default behavior is to delete everything from the preceding space character to the next space character. This means the log line is implicitly divided into fields on non-whitespace to whitespace transitions.
If a format string item does not produce output, the whole field is omitted. Space characters can be escaped with a backslash to prevent them from delimiting a field. The above behavior can be changed by adding modifiers to the format string item. A - minus modifier causes a minus to be logged if the respective item does not produce any output.
If an item with the plus modifier does not produce any output, the whole line is omitted. A number as modifier can be used to assign a log severity level to a format item. The item will only be logged if the severity of the log message is not higher than the specified log severity level.
The number can range from 1 alert over 4 warn and 7 debug to 15 trace8. This can be used to correlate which log lines belong to the same connection or request, which request happens on which connection. Notice that, as discussed above, some fields are omitted entirely because they are not defined. This option tracks additional data per worker about the currently executing request and creates a utilization summary. Note that other modules may rely on this scoreboard. This setting applies to the entire server and cannot be enabled or disabled on a virtualhost-by-virtualhost basis.
The collection of extended status information can slow down the server. Also note that this setting cannot be changed during a graceful restart. Such modules rely on collecting detailed information about the state of all workers. The previous default was always Off. The FileETag directive configures the file attributes that are used to create the ETag entity tag response header field when the document is based on a static file. The ETag value is used in cache management to save network bandwidth.
The FileETag directive allows you to choose which of these -- if any -- should be used. The recognized keywords are:. Any keyword appearing without such a prefix immediately and completely cancels the inherited setting. The directives given within this section will be applied to any object with a basename last component of filename matching the specified filename. The filename argument should include a filename, or a wild-card string, where?
This allows users to control access to their own files, at a file-by-file level. However, it accepts a regular expression. This directive allows to configure the maximum number of pipelined responses, which remain pending so long as pipelined request are received. When the limit is reached, reponses are forcibly flushed to the network in blocking mode, until passing under the limit again. FlushMaxPipelined helps constraining memory usage. When set to 0 pipelining is disabled, when set to -1 there is no limit FlushMaxThreshold still applies.
This directive allows to configure the threshold for pending output data in bytes. When the limit is reached, data are forcibly flushed to the network in blocking mode, until passing under the limit again. FlushMaxThreshold helps constraining memory usage. When set to 0 or a too small value there are actually no pending data, but for threaded MPMs there can be more threads busy waiting for the network thus less ones available to handle the other simultaneous connections.
When placed into an. For example, if you had a directory full of GIF files, but did not want to label them all with. Note that this directive overrides other indirect media type associations defined in mime. You can also override more general ForceType settings by using the value of None :. This directive primarily overrides the content types generated for static files served out of the filesystem. For resources other than static files, where the generator of the response typically specifies a Content-Type, this directive has no effect.
When explicit directives such as SetHandler or AddHandler do not apply to the current request, the internal handler name normally set by those directives is set to match the content type specified by this directive. Configurations that rely on such "magic" types should be avoided by the use of SetHandler or AddHandler. When the server has been compiled with gprof profiling support, GprofDir causes gmon. This directive currently only works with the prefork MPM.
The value Double refers to doing double-reverse DNS lookup. That is, after a reverse lookup is performed, a forward lookup is then performed on that result. At least one of the IP addresses in the forward lookup must match the original address. This is necessary for security.
Note that the result of this double-reverse isn't generally available unless you set HostnameLookups Double. The default is Off in order to save the network traffic for those sites that don't truly need the reverse lookups done. It is also better for the end users because they don't have to suffer the extra latency that a lookup entails.
Heavily loaded sites should leave this directive Off , since DNS lookups can take considerable amounts of time. The utility logresolve , compiled by default to the bin subdirectory of your installation directory, can be used to look up host names from logged IP addresses offline. Finally, if you have hostname-based Require directives , a hostname lookup will be performed regardless of the setting of HostnameLookups.
Due to legacy modules, applications or custom user-agents which must be deprecated the Unsafe option has been added to revert to the legacy behaviors. The directive accepts three parameters from the following list of choices, applying the default to the ones not specified:. Prior to the introduction of this directive, the Apache HTTP Server request message parsers were tolerant of a number of forms of input which did not conform to the protocol.
As of the introduction of this directive, all grammar rules of the specification are enforced in the default Strict operating mode, and the strict whitespace suggested by section 3.
Users are strongly cautioned against toggling the Unsafe mode of operation, particularly on outward-facing, publicly accessible server deployments.
If an interface is required for faulty monitoring or other custom service consumers running on an intranet, users should toggle the Unsafe option only on a specific virtual host configured to service their internal private network.
This already happens when the LenientMethods option is used, but administrators may wish to toggle the RegisteredMethods option and register any non-standard methods using the RegisterHttpMethod directive, particularly if the Unsafe option has been toggled. The RegisteredMethods option should not be toggled for forward proxy hosts, as the methods supported by the origin servers are unknown to the proxy server.
The Require1. Reviewing the messages logged to the ErrorLog , configured with LogLevel debug level, can help identify such faulty requests along with their origin.
Users should pay particular attention to the responses in the access log for invalid requests which were unexpectedly rejected. It is also possible to use regular expressions,.
These operations can be done on request headers req , environment variables env , and a large number of other properties. Only directives that support the directory context can be used within this configuration section. If test is false, everything between the start and end markers is ignored. In the former case, the directives between the start and end markers are only processed if the parameter named parameter-name is defined.
The second format reverses the test, and only processes the directives if parameter-name is not defined. The parameter-name argument is a define as given on the httpd command line via -D parameter at the time the server was started or by the Define directive. In the former case, the directives between the start and end markers are only processed if a directive of the given name is available at the time of processing.
The second format reverses the test, and only processes the directives if directive-name is not available. If filename doesn't exist, everything between the start and end markers is ignored. If a relative filename is supplied, the check is ServerRoot relative. In the case where this directive occurs before the ServerRoot , the path will be checked relative to the compiled-in server root or the server root passed in on the command line via the -d parameter.
In the former case, the directives between the start and end markers are only processed if the module named module is included in Apache httpd -- either compiled in or dynamically loaded using LoadModule. The second format reverses the test, and only processes the directives if module is not included.
The module argument can be either the module identifier or the file name of the module, at the time it was compiled. In the former case, the directives between the start and end markers are only processed if a section directive of the given name is available at the time of processing. The second format reverses the test, and only processes the directives if section-name is not an available section directive.
This directive allows inclusion of other configuration files from within the server configuration files. Shell-style fnmatch wildcard characters can be used in the filename or directory parts of the path to include several files at once, in alphabetical order.
In addition, if Include points to a directory, rather than a file, Apache httpd will read all files in that directory and any subdirectory. However, including entire directories is not recommended, because it is easy to accidentally leave temporary files in a directory that can cause httpd to fail. The Include directive will fail with an error if a wildcard expression does not match any file. The IncludeOptional directive can be used if non-matching wildcards should be ignored. The file path specified may be an absolute path, or may be relative to the ServerRoot directory.
Or, providing paths relative to your ServerRoot directory:. Wildcards may be included in the directory or file portion of the path. Alternatively, the following command will just be ignored in case of missing files or directories:. It works identically to the Include directive, but it will be silently ignored instead of causing an error if wildcards are used and they do not match any file or directory or if a file path does not exist on the file system. If the client requests it, chunked encoding will be used in order to send content of unknown length over persistent connections.
When a client uses a Keep-Alive connection, it will be counted as a single "request" for the MaxConnectionsPerChild directive, regardless of how many requests are sent using the connection. The number of seconds Apache httpd will wait for a subsequent request before closing the connection. By adding a postfix of ms the timeout can be also set in milliseconds. Once a request has been received, the timeout value specified by the Timeout directive applies.
Setting KeepAliveTimeout to a high value may cause performance problems in heavily loaded servers. The higher the timeout, the more server processes will be kept occupied waiting on connections with idle clients. If KeepAliveTimeout is not set for a name-based virtual host, the value of the first defined virtual host best matching the local IP and port will be used.
Access controls are normally effective for all access methods, and this is the usual desired behavior. The method name is case-sensitive. For example, given the following configuration, all users will be authorized for POST requests, and the Require group editors directive will be ignored in all cases:.
An internal redirect happens, for example, when using the Action directive, which internally redirects the original request to a CGI script. A subrequest is Apache httpd's mechanism to find out what would happen for some URI if it were requested. LimitInternalRecursion prevents the server from crashing when entering an infinite loop of internal redirects or subrequests.
Such loops are usually caused by misconfigurations. The directive stores two different limits, which are evaluated on per-request basis.
The first number is the maximum number of internal redirects that may follow each other. The second number determines how deeply subrequests may be nested. If you specify only one number , it will be assigned to both limits. This directive specifies the number of bytes from 0 meaning unlimited to 2GB that are allowed in a request body. See the note below for the limited applicability to proxy requests. The LimitRequestBody directive allows the user to set a limit on the allowed size of an HTTP request message body within the context in which the directive is given server, per-directory, per-file or per-location.
If the client request exceeds that limit, the server will return an error response instead of servicing the request. The size of a normal request message body will vary greatly depending on the nature of the resource and the methods allowed on that resource. CGI scripts typically use the message body for retrieving form information. Implementations of the PUT method will require a value at least as large as any representation that the server wishes to accept for that resource.
This directive gives the server administrator greater control over abnormal client request behavior, which may be useful for avoiding some forms of denial-of-service attacks. If, for example, you are permitting file upload to a particular location and wish to limit the size of the uploaded file to K, you might use the following directive:. Setting number at 0 means unlimited. The LimitRequestFields directive allows the server administrator to modify the limit on the number of request header fields allowed in an HTTP request.
A server needs this value to be larger than the number of fields that a normal client request might include. The number of request header fields used by a client rarely exceeds 20, but this may vary among different client implementations, often depending upon the extent to which a user has configured their browser to support detailed content negotiation.
Optional HTTP extensions are often expressed using request header fields. The value should be increased if normal clients see an error response from the server that indicates too many fields were sent in the request. When name-based virtual hosting is used, the value for this directive is taken from the default first-listed virtual host for the local IP and port combination.
This directive specifies the number of bytes that will be allowed in an HTTP request header. A server needs this value to be large enough to hold any one header field from a normal client request. The size of a normal request header field will vary greatly among different client implementations, often depending upon the extent to which a user has configured their browser to support detailed content negotiation.
When name-based virtual hosting is used, the value for this directive is taken from the default first-listed virtual host best matching the current IP address and port combination. This directive sets the number of bytes that will be allowed on the HTTP request-line.
A server needs this value to be large enough to hold any of its resource names, including any information that might be passed in the query part of a GET request. Limit in bytes on maximum size of an XML-based request body. A value of 0 will disable any checking. This has several consequences. Since several different URLs may map to the same filesystem location, such access controls may by circumvented. The enclosed directives will be applied to the request if the path component of the URL meets any of the following criteria:.
This section only applies to standalone Blazor WebAssembly apps. Hosted Blazor apps use a default ASP. NET Core app web. IIS can be configured via web. For an example configuration file, see web. Additional configuration of the example web. When the module isn't installed, the web. This prevents the IIS Manager from loading the website's configuration and the website from serving Blazor's static files. Azure Storage static file hosting allows serverless Blazor app hosting. If files aren't loaded at runtime due to inappropriate MIME types in the files' Content-Type headers, take either of the following actions:.
For more information, see Static website hosting in Azure Storage. The following nginx. Initially, set the value to at least Increase the value if browser developer tools or a network traffic tool indicates that requests are receiving a - Service Unavailable status code. Create the Apache configuration file. The following example is a simplified configuration file blazorapp.
NET Foundation or Microsoft. Blazor WebAssembly apps can accept the following host configuration values as command-line arguments at runtime in the development environment. The --contentroot argument sets the absolute path to the directory that contains the app's content files content root.
Pass the argument when running the app locally at a command prompt. From the app's directory, execute:. Add an entry to the app's launchSettings. This setting is used when the app is run with the Visual Studio Debugger and from a command prompt with dotnet run. Setting the argument in the Visual Studio property page adds the argument to the launchSettings.
For more information, see App base path. This setting is used when running the app with the Visual Studio Debugger and from a command prompt with dotnet run. The --urls argument sets the IP addresses or host addresses with ports and protocols to listen on for requests. NET Core to work with proxy servers and load balancers. For more information on setting the app's base path, including sub-app path configuration, see Host and deploy ASP.
Follow the guidance for an ASP. In case you have a need to change the filename extensions of the app's published. After publishing the app, use a shell script or DevOps build pipeline to rename. Target the. In the following examples,. To use a different file extension than. To address the compressed blazor. The preceding guidance also applies when service worker assets are in use. Otherwise, file integrity checks fail in the browser. When renaming and lazy loading the same assemblies, see the guidance in Lazy load assemblies in ASP.
In rare cases, lingering files from a prior deployment can corrupt a new deployment. Completely deleting the existing deployment or locally-published app prior to deployment may resolve the issue with a corrupted deployment. Often, deleting the existing deployment once is sufficient to resolve the problem, including for a DevOps build and deploy pipeline. If you determine that clearing a prior deployment is always required when a DevOps build and deploy pipeline is in use, you can temporarily add a step to the build pipeline to delete the prior deployment for each new deployment until you troubleshoot the exact cause of the corruption.
When Blazor WebAssembly downloads an app's startup files, it instructs the browser to perform integrity checks on the responses. It uses information in the blazor. This is beneficial for the following reasons:. If your web server returns responses that don't match the expected SHA hashes, you will see an error similar to the following appear in the browser's developer console:.
The resource has been blocked. In most cases, this is not a problem with integrity checking itself. Instead, it means there is some other problem, and the integrity check is warning you about that other problem.
When an app is built, the generated blazor. The integrity check passes as long as the SHA hashes in blazor. If you confirm that the server is returning plausibly correct data, there must be something else modifying the contents in between build and delivery of the file.
To investigate this:. Use the integrity. The script is provided for PowerShell Core 7 or later as a starting point when the app has integrity issues that the Blazor framework can't identify.
Customization of the script might be required for your apps, including if running on version of PowerShell later than version 7. The script checks the files in the publish folder and downloaded from the deployed app to detect issues in the different manifests that contain integrity hashes. These checks should detect the most common problems:.
Docs GitHub repository, the integrity. Usually, the file is trapped by a virus scanner's heuristic scanning technology, which merely looks for patterns in files that might indicate the presence of malware. To prevent the virus scanner from quarantining the file, add an exception to the virus scanner prior to cloning the repo.
The following example is a typical path to the script on a Windows system. Adjust the path as needed for other systems. Warning : Creating virus scanner exceptions is dangerous and should only be performed when you're certain that the file is safe. Comparing the checksum of a file to a valid checksum value doesn't guarantee file safety, but modifying a file in a way that maintains a checksum value isn't trivial for malicious users. Therefore, checksums are useful as a general security approach.
Compare the checksum of the local integrity. Obtain the file's checksum on Windows OS with the following command. If you have any cause for concern that checksum validation isn't secure enough in your environment, consult your organization's security leadership for guidance. Was this article helpful? With a background in both design and writing, he aims to bring a fresh perspective to writing for IT, making complicated concepts easy to understand and approach.
Next you should read. This tutorial shows you how to install, configure, and perform basic commands in Apache Hive. Improve your Apache Hadoop is the go-to framework for storing and processing big data. This article provides clear-cut
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