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PHP

By Erik


Image by/from

  • Rasmus_Lerdorf_2003.jpg: Sebastian Bergmann (Sebastian Bergmann @ Flickr)
  • derivative work: Austin512 (talk)

since version 7.0:

PHP is a general-purpose scripting language especially suited to web development. It was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1994; the PHP reference implementation is now produced by The PHP Group. PHP originally stood for Personal Home Page, but it now stands for the recursive initialism PHP: Hypertext Preprocessor.

PHP code is usually processed on a web server by a PHP interpreter implemented as a module, a daemon or as a Common Gateway Interface (CGI) executable. On a web server, the result of the interpreted and executed PHP code – which may be any type of data, such as generated HTML or binary image data – would form the whole or part of a HTTP response. Various web template systems, web content management systems, and web frameworks exist which can be employed to orchestrate or facilitate the generation of that response. Additionally, PHP can be used for many programming tasks outside of the web context, such as standalone graphical applications and robotic drone control. Arbitrary PHP code can also be interpreted and executed via command-line interface (CLI).

The standard PHP interpreter, powered by the Zend Engine, is free software released under the PHP License. PHP has been widely ported and can be deployed on most web servers on almost every operating system and platform, free of charge.

The PHP language evolved without a written formal specification or standard until 2014, with the original implementation acting as the de facto standard which other implementations aimed to follow. Since 2014, work has gone on to create a formal PHP specification.

By September 2020, two out of every three websites using PHP are still on discontinued PHP versions, and almost half of all PHP websites use version 5.6 or older, that not even Debian supports (while Debian 9 still supports version 7.0 and 7.1, those versions are unsupported by The PHP Development Team). In addition, PHP version 7.2, the most popular supported PHP version, will stop getting security updates on November 30, 2020, in less than 2 months, and therefore unless PHP websites are upgraded to version 7.3 (or newer), 84% of PHP websites will thus use discontinued versions.

PHP development began in 1994 when Rasmus Lerdorf wrote several Common Gateway Interface (CGI) programs in C, which he used to maintain his personal homepage. He extended them to work with web forms and to communicate with databases, and called this implementation “Personal Home Page/Forms Interpreter” or PHP/FI.

PHP/FI could be used to build simple, dynamic web applications. To accelerate bug reporting and improve the code, Lerdorf initially announced the release of PHP/FI as “Personal Home Page Tools (PHP Tools) version 1.0” on the Usenet discussion group comp.infosystems.www.authoring.cgi on June 8, 1995. This release already had the basic functionality that PHP has today. This included Perl-like variables, form handling, and the ability to embed HTML. The syntax resembled that of Perl, but was simpler, more limited and less consistent.

An example of the early PHP syntax:

Early PHP was not intended to be a new programming language, and grew organically, with Lerdorf noting in retrospect: “I don’t know how to stop it, there was never any intent to write a programming language […] I have absolutely no idea how to write a programming language, I just kept adding the next logical step on the way.” A development team began to form and, after months of work and beta testing, officially released PHP/FI 2 in November 1997.

The fact that PHP was not originally designed, but instead was developed organically has led to inconsistent naming of functions and inconsistent ordering of their parameters. In some cases, the function names were chosen to match the lower-level libraries which PHP was “wrapping”, while in some very early versions of PHP the length of the function names was used internally as a hash function, so names were chosen to improve the distribution of hash values.

Zeev Suraski and Andi Gutmans rewrote the parser in 1997 and formed the base of PHP 3, changing the language’s name to the recursive acronym PHP: Hypertext Preprocessor. Afterwards, public testing of PHP 3 began, and the official launch came in June 1998. Suraski and Gutmans then started a new rewrite of PHP’s core, producing the Zend Engine in 1999. They also founded Zend Technologies in Ramat Gan, Israel.

On May 22, 2000, PHP 4, powered by the Zend Engine 1.0, was released. By August 2008 this branch reached version 4.4.9. PHP 4 is no longer under development nor will any security updates be released.

On July 14, 2004, PHP 5 was released, powered by the new Zend Engine II. PHP 5 included new features such as improved support for object-oriented programming, the PHP Data Objects (PDO) extension (which defines a lightweight and consistent interface for accessing databases), and numerous performance enhancements. In 2008, PHP 5 became the only stable version under development. Late static binding had been missing from PHP and was added in version 5.3.

Many high-profile open-source projects ceased to support PHP 4 in new code from February 5, 2008, because of the GoPHP5 initiative, provided by a consortium of PHP developers promoting the transition from PHP 4 to PHP 5.

Over time, PHP interpreters became available on most existing 32-bit and 64-bit operating systems, either by building them from the PHP source code, or by using pre-built binaries. For PHP versions 5.3 and 5.4, the only available Microsoft Windows binary distributions were 32-bit IA-32 builds, requiring Windows 32-bit compatibility mode while using Internet Information Services (IIS) on a 64-bit Windows platform. PHP version 5.5 made the 64-bit x86-64 builds available for Microsoft Windows.

Official security support for PHP 5.6 ended on 31 December 2018.

PHP received mixed reviews due to lacking native Unicode support at the core language level. In 2005, a project headed by Andrei Zmievski was initiated to bring native Unicode support throughout PHP, by embedding the International Components for Unicode (ICU) library, and representing text strings as UTF-16 internally. Since this would cause major changes both to the internals of the language and to user code, it was planned to release this as version 6.0 of the language, along with other major features then in development.

However, a shortage of developers who understood the necessary changes, and performance problems arising from conversion to and from UTF-16, which is rarely used in a web context, led to delays in the project. As a result, a PHP 5.3 release was created in 2009, with many non-Unicode features back-ported from PHP 6, notably namespaces. In March 2010, the project in its current form was officially abandoned, and a PHP 5.4 release was prepared containing most remaining non-Unicode features from PHP 6, such as traits and closure re-binding. Initial hopes were that a new plan would be formed for Unicode integration, but by 2014 none had been adopted.

During 2014 and 2015, a new major PHP version was developed, which was numbered PHP 7. The numbering of this version involved some debate among internal developers. While the PHP 6 Unicode experiment had never been released, several articles and book titles referenced the PHP 6 name, which might have caused confusion if a new release were to reuse the name. After a vote, the name PHP 7 was chosen.

The foundation of PHP 7 is a PHP branch that was originally dubbed PHP next generation (phpng). It was authored by Dmitry Stogov, Xinchen Hui and Nikita Popov, and aimed to optimize PHP performance by refactoring the Zend Engine while retaining near-complete language compatibility. By 14 July 2014, WordPress-based benchmarks, which served as the main benchmark suite for the phpng project, showed an almost 100% increase in performance. Changes from phpng are also expected to make it easier to improve performance in the future, as more compact data structures and other changes are seen as better suited for a successful migration to a just-in-time (JIT) compiler. Because of the significant changes, the reworked Zend Engine is called Zend Engine 3, succeeding Zend Engine 2 used in PHP 5.

Because of major internal changes in phpng it must receive a new major version number of PHP, rather than a minor PHP 5 release, according to PHP’s release process. Major versions of PHP are allowed to break backward-compatibility of code and therefore PHP 7 presented an opportunity for other improvements beyond phpng that require backward-compatibility breaks. In particular, it involved the following changes:

PHP 7 also included new language features. Most notably, it introduces return type declarations for functions which complement the existing parameter type declarations, and support for the scalar types (integer, float, string, and boolean) in parameter and return type declarations.

PHP 8 is scheduled to be released on November 26, 2020. PHP 8 is currently in beta. New features and notable changes include:

PHP 8 is a major version and has breaking changes from previous versions.

Always available hash extension, Password Hash Registry, Split multibyte string, Reflection for references, Unbundle ext/wddx, New custom object serialization mechanism

Beginning on June 28, 2011, the PHP Development Team implemented a timeline for the release of new versions of PHP. Under this system, at least one release should occur every month. Once per year, a minor release should occur which may include new features. Every minor release should at least be supported for two years with security and bug fixes, followed by at least one year of only security fixes, for a total of a three-year release process for every minor release. No new features, unless small and self-contained, are to be introduced into a minor release during the three-year release process.
Latest versions of PHP are PHP 7.2.32, PHP 7.3.20 and PHP 7.4.8.

The mascot of the PHP project is the elePHPant, a blue elephant with the PHP logo on its side, designed by Vincent Pontier in 1998. “The (PHP) letters were forming the shape of an elephant if viewed in a sideways angle.” The elePHPant is sometimes differently colored when in plush toy form.

Many variations of this mascot have been made over the years. Only the elePHPants based on the original design by Vincent Pontier are considered official by the community. These are collectible and some of them are extremely rare.

The following “Hello, World!” program is written in PHP code embedded in an HTML document:

However, as no requirement exists for PHP code to be embedded in HTML, the simplest version of Hello, World! may be written like this, with the closing tag omitted as preferred in files containing pure PHP code

The PHP interpreter only executes PHP code within its delimiters. Anything outside its delimiters is not processed by PHP, although non-PHP text is still subject to control structures described in PHP code. The most common delimiters are to close PHP sections. The shortened form , in XHTML and other XML documents, creates correctly formed XML processing instructions. This means that the resulting mixture of PHP code and other markup in the server-side file is itself well-formed XML.

Variables are prefixed with a dollar symbol, and a type does not need to be specified in advance. PHP 5 introduced type declarations that allows functions to force their parameters to be objects of a specific class, arrays, interfaces or callback functions. However, before PHP 7.0, type declarations could not be used with scalar types such as integer or string.

Unlike function and class names, variable names are case sensitive. Both double-quoted (“”) and heredoc strings provide the ability to interpolate a variable’s value into the string. PHP treats newlines as whitespace in the manner of a free-form language, and statements are terminated by a semicolon. PHP has three types of comment syntax: /* */ marks block and inline comments; // or # are used for one-line comments. The echo statement is one of several facilities PHP provides to output text.

In terms of keywords and language syntax, PHP is similar to the C style syntax. if conditions, for and while loops, and function returns are similar in syntax to languages such as C, C++, C#, Java and Perl.

PHP is a loosely coupled language. Since, it does not depends on the data type. This is the one of main features of this language.It stores integers in a platform-dependent range, either as a 32, 64 or 128-bit signed integer equivalent to the C-language long type. Unsigned integers are converted to signed values in certain situations, which is different behavior to many other programming languages. Integer variables can be assigned using decimal (positive and negative), octal, hexadecimal, and binary notations.

Floating point numbers are also stored in a platform-specific range. They can be specified using floating point notation, or two forms of scientific notation. PHP has a native Boolean type that is similar to the native Boolean types in Java and C++. Using the Boolean type conversion rules, non-zero values are interpreted as true and zero as false, as in Perl and C++.

The null data type represents a variable that has no value; NULL is the only allowed value for this data type.

Variables of the “resource” type represent references to resources from external sources. These are typically created by functions from a particular extension, and can only be processed by functions from the same extension; examples include file, image, and database resources.

Arrays can contain elements of any type that PHP can handle, including resources, objects, and even other arrays. Order is preserved in lists of values and in hashes with both keys and values, and the two can be intermingled. PHP also supports strings, which can be used with single quotes, double quotes, nowdoc or heredoc syntax.

The Standard PHP Library (SPL) attempts to solve standard problems and implements efficient data access interfaces and classes.

PHP defines a large array of functions in the core language and many are also available in various extensions; these functions are well documented in the online PHP documentation. However, the built-in library has a wide variety of naming conventions and associated inconsistencies, as described under history above.

Custom functions may be defined by the developer:

In 2020, the output of the above sample program is ‘I am currently 25 years old.’

In lieu of function pointers, functions in PHP can be referenced by a string containing their name. In this manner, normal PHP functions can be used, for example, as callbacks or within function tables. User-defined functions may be created at any time without being prototyped. Functions may be defined inside code blocks, permitting a run-time decision as to whether or not a function should be defined. There is a function_exists function that determines whether a function with a given name has already been defined. Function calls must use parentheses, with the exception of zero-argument class constructor functions called with the PHP operator new, in which case parentheses are optional.

Until PHP 5.3, support for anonymous functions and closures did not exist in PHP. While create_function() has existed since PHP 4.0.1, it is merely a thin wrapper around eval() that allows normal PHP functions to be created during program execution. PHP 5.3 added syntax to define an anonymous function or “closure” which can capture variables from the surrounding scope:

In the example above, getAdder() function creates a closure using passed argument $x (the keyword use imports a variable from the lexical context), which takes an additional argument $y, and returns the created closure to the caller. Such a function is a first-class object, meaning that it can be stored in a variable, passed as a parameter to other functions, etc.

Unusually for a dynamically typed language, PHP supports type declarations on function parameters, which are enforced at runtime. This has been supported for classes and interfaces since PHP 5.0, for arrays since PHP 5.1, for “callables” since PHP 5.4, and scalar (integer, float, string and boolean) types since PHP 7.0. PHP 7.0 also has type declarations for function return types, expressed by placing the type name after the list of parameters, preceded by a colon. For example, the getAdder function from the earlier example could be annotated with types like so in PHP 7:

By default, scalar type declarations follow weak typing principles. So, for example, if a parameter’s type is int, PHP would allow not only integers, but also convertible numeric strings, floats or booleans to be passed to that function, and would convert them. However, PHP 7 has a “strict typing” mode which, when used, disallows such conversions for function calls and returns within a file.

Basic object-oriented programming functionality was added in PHP 3 and improved in PHP 4. This allowed for PHP to gain further abstraction, making creative tasks easier for programmers using the language. Object handling was completely rewritten for PHP 5, expanding the feature set and enhancing performance. In previous versions of PHP, objects were handled like value types. The drawback of this method was that code had to make heavy use of PHP’s “reference” variables if it wanted to modify an object it was passed rather than creating a copy of it. In the new approach, objects are referenced by handle, and not by value.

PHP 5 introduced private and protected member variables and methods, along with abstract classes, final classes, abstract methods, and final methods. It also introduced a standard way of declaring constructors and destructors, similar to that of other object-oriented languages such as C++, and a standard exception handling model. Furthermore, PHP 5 added interfaces and allowed for multiple interfaces to be implemented. There are special interfaces that allow objects to interact with the runtime system. Objects implementing ArrayAccess can be used with array syntax and objects implementing Iterator or IteratorAggregate can be used with the foreach language construct. There is no virtual table feature in the engine, so static variables are bound with a name instead of a reference at compile time.

If the developer creates a copy of an object using the reserved word clone, the Zend engine will check whether a __clone() method has been defined. If not, it will call a default __clone() which will copy the object’s properties. If a __clone() method is defined, then it will be responsible for setting the necessary properties in the created object. For convenience, the engine will supply a function that imports the properties of the source object, so the programmer can start with a by-value replica of the source object and only override properties that need to be changed.

The following is a basic example of object-oriented programming in PHP:

The visibility of PHP properties and methods is defined using the keywords public, private, and protected. The default is public, if only var is used; var is a synonym for public. Items declared public can be accessed everywhere. protected limits access to inherited classes (and to the class that defines the item). private limits visibility only to the class that defines the item. Objects of the same type have access to each other’s private and protected members even though they are not the same instance.

The only complete PHP implementation is the original, known simply as PHP. It is the most widely used and is powered by the Zend Engine. To disambiguate it from other implementations, it is sometimes unofficially called “Zend PHP”. The Zend Engine compiles PHP source code on-the-fly into an internal format that it can execute, thus it works as an interpreter. It is also the “reference implementation” of PHP, as PHP has no formal specification, and so the semantics of Zend PHP define the semantics of PHP. Due to the complex and nuanced semantics of PHP, defined by how Zend works, it is difficult for competing implementations to offer complete compatibility.

PHP’s single-request-per-script-execution model, and the fact the Zend Engine is an interpreter, leads to inefficiency; as a result, various products have been developed to help improve PHP performance. In order to speed up execution time and not have to compile the PHP source code every time the web page is accessed, PHP scripts can also be deployed in the PHP engine’s internal format by using an opcode cache, which works by caching the compiled form of a PHP script (opcodes) in shared memory to avoid the overhead of parsing and compiling the code every time the script runs. An opcode cache, Zend Opcache, is built into PHP since version 5.5. Another example of a widely used opcode cache is the Alternative PHP Cache (APC), which is available as a PECL extension.

While Zend PHP is still the most popular implementation, several other implementations have been developed. Some of these are compilers or support JIT compilation, and hence offer performance benefits over Zend PHP at the expense of lacking full PHP compatibility. Alternative implementations include the following:

PHP is free software released under the PHP License, which stipulates that:

Products derived from this software may not be called “PHP”, nor may “PHP” appear in their name, without prior written permission from group@php.net. You may indicate that your software works in conjunction with PHP by saying “Foo for PHP” instead of calling it “PHP Foo” or “phpfoo”.

This restriction on use of “PHP” makes the PHP License incompatible with the General Public License (GPL), while the Zend License is incompatible due to an advertising clause similar to that of the original BSD license.

PHP includes various free and open-source libraries in its source distribution, or uses them in resulting PHP binary builds. PHP is fundamentally an Internet-aware system with built-in modules for accessing File Transfer Protocol (FTP) servers and many database servers, including PostgreSQL, MySQL, Microsoft SQL Server and SQLite (which is an embedded database), LDAP servers, and others. Numerous functions familiar to C programmers, such as those in the stdio family, are available in standard PHP builds.

PHP allows developers to write extensions in C to add functionality to the PHP language. PHP extensions can be compiled statically into PHP or loaded dynamically at runtime. Numerous extensions have been written to add support for the Windows API, process management on Unix-like operating systems, multibyte strings (Unicode), cURL, and several popular compression formats. Other PHP features made available through extensions include integration with IRC, dynamic generation of images and Adobe Flash content, PHP Data Objects (PDO) as an abstraction layer used for accessing databases, and even speech synthesis. Some of the language’s core functions, such as those dealing with strings and arrays, are also implemented as extensions. The PHP Extension Community Library (PECL) project is a repository for extensions to the PHP language.

Some other projects, such as Zephir, provide the ability for PHP extensions to be created in a high-level language and compiled into native PHP extensions. Such an approach, instead of writing PHP extensions directly in C, simplifies the development of extensions and reduces the time required for programming and testing.

By December 2018 the PHP Group consisted of ten people: Thies C. Arntzen, Stig Bakken, Shane Caraveo, Andi Gutmans, Rasmus Lerdorf, Sam Ruby, Sascha Schumann, Zeev Suraski, Jim Winstead, and Andrei Zmievski.

Zend Technologies provides a PHP Certification based on PHP 5.5 exam for programmers to become certified PHP developers.

There are two primary ways for adding support for PHP to a web server – as a native web server module, or as a CGI executable. PHP has a direct module interface called Server Application Programming Interface (SAPI), which is supported by many web servers including Apache HTTP Server, Microsoft IIS, Netscape (now defunct) and iPlanet. Some other web servers, such as OmniHTTPd, support the Internet Server Application Programming Interface (ISAPI), which is a Microsoft’s web server module interface. If PHP has no module support for a web server, it can always be used as a Common Gateway Interface (CGI) or FastCGI processor; in that case, the web server is configured to use PHP’s CGI executable to process all requests to PHP files.

PHP-FPM (FastCGI Process Manager) is an alternative FastCGI implementation for PHP, bundled with the official PHP distribution since version 5.3.3. When compared to the older FastCGI implementation, it contains some additional features, mostly useful for heavily loaded web servers.

When using PHP for command-line scripting, a PHP command-line interface (CLI) executable is needed. PHP supports a CLI server application programming interface (SAPI) since PHP 4.3.0. The main focus of this SAPI is developing shell applications using PHP. There are quite a few differences between the CLI SAPI and other SAPIs, although they do share many of the same behaviors.

PHP has a direct module interface called SAPI for different web servers; in case of PHP 5 and Apache 2.0 on Windows, it is provided in form of a DLL file called .mw-parser-output .monospaced{font-family:monospace,monospace}php5apache2.dll, which is a module that, among other functions, provides an interface between PHP and the web server, implemented in a form that the server understands. This form is what is known as a SAPI.

There are different kinds of SAPIs for various web server extensions. For example, in addition to those listed above, other SAPIs for the PHP language include the Common Gateway Interface (CGI) and command-line interface (CLI).

PHP can also be used for writing desktop graphical user interface (GUI) applications, by using the PHP-GTK extension. PHP-GTK is not included in the official PHP distribution, and as an extension it can be used only with PHP versions 5.1.0 and newer. The most common way of installing PHP-GTK is compiling it from the source code.

When PHP is installed and used in cloud environments, software development kits (SDKs) are provided for using cloud-specific features. For example:

Numerous configuration options are supported, affecting both core PHP features and extensions. Configuration file php.ini is searched for in different locations, depending on the way PHP is used. The configuration file is split into various sections, while some of the configuration options can be also set within the web server configuration.

PHP is a general-purpose scripting language that is especially suited to server-side web development, in which case PHP generally runs on a web server. Any PHP code in a requested file is executed by the PHP runtime, usually to create dynamic web page content or dynamic images used on websites or elsewhere. It can also be used for command-line scripting and client-side graphical user interface (GUI) applications. PHP can be deployed on most web servers, many operating systems and platforms, and can be used with many relational database management systems (RDBMS). Most web hosting providers support PHP for use by their clients. It is available free of charge, and the PHP Group provides the complete source code for users to build, customize and extend for their own use.

PHP acts primarily as a filter, taking input from a file or stream containing text and/or PHP instructions and outputting another stream of data. Most commonly the output will be HTML, although it could be JSON, XML or binary data such as image or audio formats. Since PHP 4, the PHP parser compiles input to produce bytecode for processing by the Zend Engine, giving improved performance over its interpreter predecessor.

Originally designed to create dynamic web pages, PHP now focuses mainly on server-side scripting, and it is similar to other server-side scripting languages that provide dynamic content from a web server to a client, such as Microsoft’s ASP.NET, Sun Microsystems’ JavaServer Pages, and mod_perl. PHP has also attracted the development of many software frameworks that provide building blocks and a design structure to promote rapid application development (RAD). Some of these include PRADO, CakePHP, Symfony, CodeIgniter, Laravel, Yii Framework, Phalcon and Zend Framework, offering features similar to other web frameworks.

The LAMP architecture has become popular in the web industry as a way of deploying web applications. PHP is commonly used as the P in this bundle alongside Linux, Apache and MySQL, although the P may also refer to Python, Perl, or some mix of the three. Similar packages, WAMP and MAMP, are also available for Windows and macOS, with the first letter standing for the respective operating system. Although both PHP and Apache are provided as part of the macOS base install, users of these packages seek a simpler installation mechanism that can be more easily kept up to date.

For specific and more advanced usage scenarios, PHP offers a well defined and documented way for writing custom extensions in C or C++. Besides extending the language itself in form of additional libraries, extensions are providing a way for improving execution speed where it is critical and there is room for improvements by using a true compiled language. PHP also offers well defined ways for embedding itself into other software projects. That way PHP can be easily used as an internal scripting language for another project, also providing tight interfacing with the project’s specific internal data structures.

PHP received mixed reviews due to lacking support for multithreading at the core language level, though using threads is made possible by the “pthreads” PECL extension.

A command line interface, php-cli, and two ActiveX Windows Script Host scripting engines for PHP have been produced.

As of April 2007[update], over 20 million Internet domains had web services hosted on servers with PHP installed and mod_php was recorded as the most popular Apache HTTP Server module. As of August 2019[update], PHP was used as the server-side programming language on 78.8% of websites, down from 83.5% previously, where the language could be determined. Web content management systems written in PHP include MediaWiki, Joomla, eZ Publish, eZ Platform, SilverStripe, WordPress, Drupal, and Moodle. Websites written in PHP, in back-end and/or user-facing portion, include Facebook, Digg, Tumblr, Dailymotion, and Slack.

As of January 2013[update], PHP was used in more than 240 million websites (39% of those sampled) and was installed on 2.1 million web servers.

As of April 2020[update], PHP 7 is the most used version of the language with 50.6% of sites using PHP and 39.6% of all websites on the web.

In 2019, 11% of all vulnerabilities listed by the National Vulnerability Database were linked to PHP; historically, about 30% of all vulnerabilities listed since 1996 in this database are linked to PHP. Technical security flaws of the language itself or of its core libraries are not frequent (22 in 2009, about 1% of the total although PHP applies to about 20% of programs listed). Recognizing that programmers make mistakes, some languages include taint checking to automatically detect the lack of input validation which induces many issues. Such a feature is being developed for PHP, but its inclusion into a release has been rejected several times in the past.

There are advanced protection patches such as Suhosin and Hardening-Patch, especially designed for web hosting environments.

Historically, old versions of PHP had some configuration parameters and default values for such runtime settings that made some PHP applications prone to security issues. Among these, magic_quotes_gpc and register_globals configuration directives were the best known; the latter made any URL parameters become PHP variables, opening a path for serious security vulnerabilities by allowing an attacker to set the value of any uninitialized global variable and interfere with the execution of a PHP script. Support for “magic quotes” and “register globals” settings has been deprecated since PHP 5.3.0, and removed from PHP 5.4.0.

Another example for the potential runtime-settings vulnerability comes from failing to disable PHP execution (for example by using the engine configuration directive) for the directory where uploaded files are stored; enabling it can result in execution of malicious code embedded within the uploaded files. The best practice is to either locate the image directory outside of the document root available to the web server and serve it via intermediary script, or disable PHP execution for the directory which stores the uploaded files.

Also, enabling the dynamic loading of PHP extensions (via enable_dl configuration directive) in a shared web hosting environment can lead to security issues.

Implied type conversions that result in different values being treated as equal, sometimes against the programmer’s intent, can lead to security issues. For example, the result of the comparison ‘0e1234’ == ‘0’ is true, because strings that are parsable as numbers are converted to numbers; in this case, the first compared value is treated as scientific notation having the value (0×101234), which is zero. Errors like this resulted in authentication vulnerabilities in Simple Machines Forum, Typo3 and phpBB when MD5 password hashes were compared. The recommended way is to use hash_equals() (for timing attack safety), strcmp or the identity operator (===), as ‘0e1234’ === ‘0’ results in false.

In a 2013 analysis of over 170,000 website defacements, published by Zone-H, the most frequently (53%) used technique was exploitation of file inclusion vulnerability, mostly related to insecure usage of the PHP language constructs include, require, and allow_url_fopen.

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CPanel

By Erik

cPanel is a web hosting control panel (software that facilitates the management of a web hosting server) developed by cPanel, L.L.C., an American corporation. The software provides a graphical interface (GUI) and automation tools designed to simplify the process of hosting a web site to the website owner or the “end user”.

cPanel is part of a software suite called cPanel & WHM which provides capabilities for administrators, resellers, and end-user website owners to control the various aspects of website and server administration through a standard web browser using a three-tier structure. While cPanel is limited to managing a single hosting account, cPanel & WHM allows the administration of the entire server.

In addition to the GUI, cPanel also has command line and API-based access that allows third-party software vendors, web hosting organizations, and developers to automate standard system administration processes.

cPanel & WHM is designed to function either as a dedicated server or virtual private server. The latest cPanel & WHM version supports installation on CentOS, Red Hat Enterprise Linux (RHEL), and CloudLinux OS. cPanel 11.30 is the last major version to support FreeBSD.

Application-based support includes Apache, PHP, MySQL, PostgreSQL, Perl, and BIND (DNS). Email-based support includes POP3, IMAP, and SMTP services. cPanel is accessed via HTTPS on port 2083, while WHM is accessed via HTTPS on port 2087.

Once installed, cPanel & WHM cannot be easily removed. cPanel & WHM FAQ states that the best way to uninstall cPanel & WHM is by reformatting the server. However, uninstall guides are available online for expert server administrators who do not wish to reformat their server. Similarly, it should only be installed on a freshly installed operating system with minimal prior configuration.

cPanel has been developed by cPanel, L.L.C., a privately owned corporation headquartered in Houston, Texas, United States.

The software was originally designed in 1996 as the control panel for Speed Hosting, a now-defunct web hosting company. The original author of cPanel, John Nick Koston, had a stake in Speed Hosting. Webking quickly began using cPanel after their merger with Speed Hosting. The new company moved their servers to Virtual Development Inc. (VDI), a now-defunct hosting facility. Following an agreement between Koston and VDI, cPanel was only available to customers hosted directly at VDI. At the time there was little competition in the control panel market, with the main choices being VDI and Alabanza.

Eventually, due to Koston leaving for college, William Jensen and John Koston, signed a Split Agreement. cPanel split into a separate program called WebPanel; this version was run by VDI. Without the lead programmer, VDI was not able to continue any work on cPanel and eventually stopped supporting it completely. Koston kept working on cPanel while also working at BurstNET. Eventually, Koston left BurstNET on good terms to focus fully on cPanel. cPanel has since been updated and improved over the years.

cPanel 3 was released in 1999: main additions over cPanel 2 were an automatic upgrade and the Web Host Manager (WHM). The interface was also improved when Carlos Rego of WizardsHosting made what became the default theme of cPanel.

On August 20, 2018 cPanel L.L.C. announced it had signed an agreement to be acquired by a group led by Oakley Capital (who also own Plesk and SolusVM). While Koston sold his interest in cPanel, he will continue to be an owner of the company that owns cPanel.

To the client, cPanel provides front-ends for a number of common operations, including the management of PGP keys, crontab tasks, mail and FTP accounts, and mailing lists.

Several add-ons exist, some for an additional fee, the most notable being Auto Installers like Installatron, Fantastico, Softaculous, and WHMSonic (SHOUTcast/radio Control Panel Add-on). Auto Installers are a bundle of scripts which automate the installation (and update of) web applications such as WordPress, SMF, phpBB, Drupal, Joomla!, Tiki Wiki CMS Groupware, Geeklog, Moodle, WhyUnified.com, MagicSpam WHMCS, and ZamFoo. Fantastico is a popular Auto Installer but is losing market fast because of lack of updates (see ) and fewer number of scripts. There are free versions of the auto installers, however, they are very limited on the script the provide, and often leave out the most popular scripts like WordPress. The add-ons need to be enabled by the server administrator in WHM to be accessible to the cPanel user.

WHM manages some software packages separately from the underlying operating system, applying upgrades to Apache, PHP, MySQL, Exim, FTP, and related software packages automatically. This ensures that these packages are kept up-to-date and compatible with WHM, but makes it more difficult to install newer versions of these packages. It also makes it difficult to verify that the packages have not been tampered with since the operating system’s package management verification system cannot be used to do so.

WHM, short for WebHost Manager, is a web-based tool which is used for server administration. There are at least two tiers of WHM, often referred to as “root WHM”, and non-root WHM (or Reseller WHM). Root WHM is used by server administrators and non-root WHM (with fewer privileges) is used by others, like entity departments, and resellers to manage hosting accounts often referred to as cPanel accounts on a web server. WHM listens on ports 2086 and 2087. WHM is also used to manage SSL certificates (both server self generated and CA provided SSL certificates), cPanel users, hosting packages, DNS zones, themes, and authentication methods. Additionally, WHM can also be used to manage FTP, Mail (POP, IMAP, and SMTP) and SSH services on the server. The default automatic SSL (AutoSSL) provided by cPanel is powered by Sectigo (formerly Comodo CA) late 2018. Sectigo is now a commercial certificate authority and a provider of purpose-built and automated PKI management solutions. The company released the Sectigo Embedded Firewall for Automotive in 2019.

As well as being accessible by the root administrator, WHM is also accessible to users with reseller privileges. Reseller users of cPanel have a smaller set of features than the root user, generally limited by the server administrator, to features which they determine will affect their customers’ accounts rather than the server as a whole.
From root WHM, the server administrator can perform maintenance operations such as upgrade and recompile Apache & PHP, install Perl Modules, and upgrade RPMs installed on the system.

A version of cPanel & WHM for Microsoft Windows exists, titled Enkompass. As of October 15, 2011, Enkompass was offered free, as development for the product had been slowed. As of February 2014, Enkompass was declared end-of-life, with version 3 remaining available for download, but without further development or support.

On June 27th, 2019 cPanel announced an arguably controversial new account-based pricing structure. The new pricing structure is on a combined per-server and per-account basis that many users and partners consider cumbersome and difficult to implement, and also will result in significant price increases for some customers and providers. After the resulting backlash from their customers, cPanel issued a second announcement but notably refused to budge on the new pricing structure.

Following the price increase announcement, a number of companies have announced impending price increases for their customers. LiquidWeb, SiteGround, and Interserver are among those who no longer push cPanel as their preferred control panel. Other web hosts like MyServerPlanet, KnownHost, and D9Hosting are recommending cheaper alternatives such as DirectAdmin and Interworx. Scala Hosting and Nimbus Hosting on the other hand has decided to ramp up their development and release of its own control panel.

Filed Under: hosting service,website hosting,web hosts,expensive hosts Tagged With: expensive hosts, hosting service, web hosts, website hosting

Image hosting service

By Erik

An image hosting service allows individuals to upload images to an Internet website. The image host will then store the image onto its server, and show the individual different types of code to allow others to view that image. Some of the best known examples are Flickr, Imgur and Photobucket, each catering for different purposes.

Typically image hosting websites provide an upload interface; a form in which the uploader specifies the location of an image file on their local computer file system. After pressing a “Submit” button the file is uploaded to the image host’s server. Some image hosts allow the uploader to specify multiple files at once using this form, or the ability to upload one ZIP archive containing multiple images. Additionally, some hosts allow FTP access, where single or multiple files can be uploaded in one session using FTP software or an FTP-capable browser.

After this process, the image is hosted on the server. Typically this means that the image is available on the web (to the public). The uploader may also be allowed to specify inline links to the hosted image, in order to embed it on other websites e.g.

Usually, the image host will put restrictions on the maximum image size allowed, or the maximum space or bandwidth allowed per user. Due to bandwidth costs, free services usually offer relatively modest size limits per image when compared to paid services, but allow users hotlinking their images.

Image hosts also allow tools such as the ability to create photoblogs/galleries with your images, or add them to a slide show for easier viewing. Some offer more advanced tools such as the ability for anl to ato an image they uploaded, sideloaders, or browser sidebars. Other hosts have introduced novel features such as the ability to automatically resize images down to a user-selected size. A Flickr tool allows one to upload photos using a camera phone with email capability.

Hosting services have the potential ability to identify when and where their images are being used. When an image file is accessed, the image host is capable of logging the date and the general numeric internet address of the request.

In the case of spam, the messages often include unique image URLs that are specific to that message only. The unique URL is used as a tracking ID, so that the image host can identify exactly what message intended for what specific recipient has been viewed, in addition to the date and host accessing the image. This is why many email reading systems do not show images by default, to protect the reader from having their reading of spam being tracked by the email senders.

Many image hosts are free, some do not even require registration. Of the free image hosts, the vast majority are supported by advertisements, mostly on their top pages, thumbnail pages, or “not found” pages. Showing advertisements to users has enabled image size and bandwidth limits to increase.

Some free hosts have optional paid image hosting functions, while other hosts offer only paid services. Features and storage available are generally better for paid services, while cost is still much less than the cost of purchasing webhosting to operate a website. Paid services often allow users to have password protected photo albums, customizable skins, and customized subdomains. There are many other paid services available that offer different packages of options, features, and costs.

Before the development of image hosting services, the display and exchange of images on the early public Internet of the 1980s-1990s was a laborious and complex process. Expertise was needed to set up a private file server, to connect it to the Internet, and paying for the potentially expensive dedicated Internet connection. Some experts would provide access to a Unix shell and some file storage, via paid access, free public access, or just made available to a select group of private friends. Uploading of images was accomplished with command-line tools like FTP, or uploading images using slow 14.4 to 33.6 kilobit dialup modem connections and terminal protocols like XMODEM to the server storage.

Before the Web was developed, images would primarily be downloaded manually from file servers or from binary newsgroups on Usenet, and displayed with a separate image viewer. The expansion of the Web in the 1990s brought text and images together, allowing for inline display of images without separate downloading, but still required the above expertise and methods to make the images available.

Also, on the early web, some technical knowledge was required to know how to even make an uploaded image display on a discussion forum. Typically, images would accessed using a URL format similar to:

but to make the image actually display in a discussion forum, this would need to be manually rewritten in HTML markup in the forum post, as

One of the primary new features of the early and developing Web that enabled the easy sharing of images and other data, was the concept of being able to upload or HTTP POST a file via the web browser to the remote server. This alone helped to eliminate all the complex steps of needing to understand command line tools like FTP or uploading via a modem terminal.

Early image and data storage servers also initially left the uploaded content unchanged, sometimes resulting in undesirable web page display problems, such as too high resolution causing page layout problems in discussion forums, or too high detail causing very slow page loading times. The sharing of potentially incompatible image formats could also result in them not displaying properly for some viewers.

The early and developing image sharing services eventually added the ability to automatically resize and recompress uploaded images into standardized sizes and formats, for maximum browser compatibility and minimizing of bandwidth usage for unnecessarily large images.

The provision for early image sharing services to automatically create sharing links also reduced the need for technical knowledge of where the image was uploaded.

Filed Under: hosting service,website hosting,web hosts,expensive hosts Tagged With: expensive hosts, hosting service, web hosts, website hosting

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