Internet Information Services

Internet Information Services

History

Sale Kutte The first Microsoft webserver was a research project by the European Microsoft Windows NT Academic Centre (EMWAC), part of the University of Edinburgh in Scotland, and was distributed as freeware. However since the EMWAC server was unable to scale sufficiently to handle the volume of traffic going to microsoft.com, Microsoft was forced to develop its own webserver, IIS.


IIS was initially released as an additional set of Internet-based services for Windows NT 3.51. IIS 2.0 followed, adding support for the Windows NT 4.0 operating system; and IIS 3.0 introduced the Active Server Pages dynamic scripting environment.


IIS 4.0 dropped support for the Gopher protocol and was bundled with Windows NT as a separate "Option Pack".[citation needed]


The current shipping version of IIS is 7.5 for Windows 7 and Windows Server 2008 R2, 7.0 for Windows Vista and Windows Server 2008, 6.0 for Windows Server 2003 and Windows XP Professional x64 Edition, and IIS 5.1 for Windows XP Professional. Windows XP has a restricted version of IIS 5.1 that supports only 10 simultaneous connections and a single web site. IIS 6.0 added support for IPv6. A FastCGI module is also available for IIS5.1, IIS6 and IIS7.


IIS 7.0 is not installed by Windows Vista by default but it can be selected from the list of optional components. It is available in all editions of Windows Vista including Home Basic. IIS 7 on Vista does not limit the number of allowed connections as IIS on XP did but limits concurrent requests to 10 (Windows Vista Ultimate, Business, and Enterprise Editions) or 3 (Vista Home Premium). Additional requests are queued which hampers performance but they are not rejected as with XP.


IIS 7.0 (Windows Vista/2008) is much faster than IIS 5.1 (Windows XP) because it relies on the HTTP.SYS kernel driver.

Microsoft Web Platform Installer

Microsoft Web Platform Installer (WPI) is a simple, free tool that automates the installation of Microsoft's Web Platform technologies (such as IIS, ASP.NET, and PHP) and certain 3rd-party software.

Security

Earlier versions of IIS were hit with a number of vulnerabilities, chief among them CA-2001-19 which led to the infamous Code Red worm; however, both versions 6.0 and 7.0 currently have no reported issues with this specific vulnerability. In IIS 6.0 Microsoft opted to change the behaviour of pre-installed ISAPI handlers, many of which were culprits in the vulnerabilities of 4.0 and 5.0, thus reducing the attack surface of IIS. In addition, IIS 6.0 added a feature called "Web Service Extensions" that prevents IIS from launching any program without explicit permission by an administrator. With the current release IIS 7.0 the components are modularised so that only the required components have to be installed, thus further reducing the attack surface. In addition, security features are added such as URLFiltering which rejects suspicious URLs based on a user-defined rule set.


By default IIS 5.1 and lower run websites in-process under the SYSTEM account,a default Windows account with 'superuser' rights. Under 6.0 all request handling processes have been brought under a Network Services account with significantly fewer privileges so that should there be a vulnerability in a feature or in custom code it won't necessarily compromise the entire system given the sandboxed environment these worker processes run in. IIS 6.0 also contained a new kernel HTTP stack (http.sys) with a stricter HTTP request parser and response cache for both static and dynamic content.


There are various built-in security features from Microsoft. Many companies offer third-party security tools and features, also known as "Web App Firewalls, or Web Application Firewalls." The advantage of such tools is that they offer much more comprehensive elements (such as easy-to-use GUI, etc.) that aid in protecting an IIS installation with an additional layer of protection at a higher level.

Authentication Mechanisms

IIS 5.0 and higher support the following authentication mechanisms:


* Basic access authentication
* Digest access authentication
* Integrated Windows Authentication
* .NET Passport Authentication (not supported in Windows Server 2008 and above)


IIS 6.0 Technet reference


IIS 7 Config reference


Authentication changed slightly between IIS6 and IIS7, most notably in that the anonymous user which was named "IUSR_{machinename}" is a built-in account in Vista and future operating systems and named "IUSR". Other changes in authentication are noted on the iis.net website


Notably, in IIS 7, each authentication mechanism is isolated into its own module and can be installed or uninstalled independently. See the Native Modules list in this article on IIS.net

Version 7.0

Debuting with Windows Vista, and included in Windows Server 2008, IIS 7.0 features a modular architecture, much like Apache. Instead of a monolithic server which features all services, IIS 7 has a core web server engine. Modules offering specific functionality can be added to the engine to enable its features. The advantage of having this architecture is that only the features required can be enabled and that the functionalities can be extended by using custom modules.


IIS 7 will ship with a handful of modules, but Microsoft will make other modules available online. The following sets of modules are slated to ship with the server:


1. HTTP Modules
2. Security Modules
3. Content Modules
4. Compression Modules
5. Caching Modules
6. Logging and Diagnostics Modules


Running IIS 7 with the extension component Ape by Helicon Tech allows emulating Apache's runtime environment including more than a dozen Apache modules (mod_rewrite, mod_proxy, mod_auth, mod_cache, etc.), as well as direct .htaccess support, inside IIS.


Writing extensions to IIS 7 using ISAPI has been deprecated in favor of the module API, which allows modules to be plugged in anywhere within the request processing pipeline. Much of IIS's own functionality is built on this API, and as such, developers will have much more control over a request process than was possible in prior versions. Modules can be written using C++, or using the IHttpModule interface from a .NET Framework language. Modules can be loaded globally where the services provided by the module can affect all sites, or loaded on a per-site basis. IIS 7 has an integrated mode application pool where .NET modules are loaded into the pipeline using the module API, rather than ISAPI. As a result ASP.NET code can be used with all requests to the server. For applications requiring strict IIS 6.0 compatibility, the Classic application pool mode loads asp.NET as an ISAPI.


A significant change from previous versions of IIS is that all Web server configuration information is stored solely in XML configuration files, instead of in the metabase. The server has a global configuration file that provides defaults, and each virtual web's document root (and any subdirectory thereof) may contain a web.config containing settings that augment or override the defaults. Changes to these files take effect immediately. This marks a significant departure from previous versions whereby web interfaces, or machine administrator access, were required to change simple settings such as default document, active modules and security/authentication. It also eliminates the need to perform metabase synchronization between multiple servers in a farm of web servers.


IIS 7 also features a completely rewritten administration interface that takes advantage of modern MMC features such as task panes and asynchronous operation. Configuration of ASP.NET is more fully integrated into the administrative interface.

Other changes:

* PICS content ratings, support for Microsoft Passport, and server-side image maps are no longer included.
* Executing commands via server-side includes is no longer permitted.
* IISRESET -reboot has been removed.
* The CONVLOG tool, which converts IIS log files into NCSA format, has been removed.
* Support for enabling a folder for "Web Sharing" via the Windows Explorer interface has been removed.
* IIS Media Pack (see below), which allows IIS to be used as a bare-bones media server, without using Windows Media Services.
* New FTP module, that integrates with the new configuration store, as well as the new management environment.