Internet Information Services

Internet Information Services

Screenshot of IIS Manager console of Internet Information Services 7
Developer(s)	Microsoft
Stable release	7.5 / 22 October 2009; 2 years ago (2009-10-22)
Operating system	Windows NT 3.51 and later (full list)
Type	Web server, mail server and FTP server
License	IIS: proprietary integral component of Microsoft Windows IIS Express: Freeware
Website	www.iis.net

Internet Information Services (IIS) – formerly called Internet Information Server – is a web server application and set of feature extension modules created by Microsoft for use with Microsoft Windows. It is the most used web server after Apache HTTP Server. IIS 7.5 supports HTTP, HTTPS, FTP, FTPS, SMTP and NNTP. It is an integral part of Windows Server family of products, as well as certain editions of Windows XP, Windows Vista and Windows 7. IIS is not turned on by default when Windows is installed.

History

The first Microsoft web server was a research project at European Microsoft Windows NT Academic Centre (EMWAC), part of the University of Edinburgh in Scotland, and was distributed as freeware.^[1] 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 web server, IIS.^[2]

Almost every version of IIS was released either alongside or with a version of Microsoft Windows operating system. IIS 1.0 was initially released as a free add-on, a set of web-based services for Windows NT 3.51. However, IIS 2.0 was included with Windows NT 4.0. IIS 3.0, which was included with Service Pack 3 of Windows NT 4, introduced the Active Server Pages dynamic scripting environment.^[3] IIS 4.0 was released as part of an "Option Pack" for Windows NT 4.0 and dropped support for the Gopher protocol.^{[citation needed]} IIS 5.0 shipped with Windows 2000 and introduced additional authentication methods, management enhancements including a new MMC based administration application, support for the WebDAV protocol, and enhancements to ASP.^[4] IIS 5.1 was shipped with Windows XP Professional, and was nearly identical to IIS 5.0 on Windows 2000 except for several limitations Microsoft introduced. IIS 5.1 supported only 10 simultaneous connections and supported only a single web site.^[5][6] IIS 6.0, included with Windows Server 2003 and Windows XP Professional x64 Edition, added support for IPv6 and included a new worker process model that increased security as well as reliability.^[7]

IIS 7.0 was a complete redesign and rewrite of IIS, and was shipped with Windows Vista and Windows Server 2008. IIS 7.0 included a new modular design that allowed for a reduced attack surface and increased performance. IIS 7.0 also introduced a hierarchical configuration system allowing for simpler site deploys, a new Windows Forms based management application, new command line management options and increased support for the .NET Framework.^[8] IIS 7.0 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.

The current shipping version of IIS is IIS 7.5, included in Windows 7 and Windows Server 2008 R2. IIS 7.5 improved WebDAV and FTP modules as well as command line administration in PowerShell. It also introduced Best Practices Analyzer tool and process isolation for application pools.^[9]

Versions

• IIS 1.0, Windows NT 3.51 available as a free add-on
• IIS 2.0, Windows NT 4.0
• IIS 3.0, Windows NT 4.0 Service Pack 2^[10]
• IIS 4.0, Windows NT 4.0 Option Pack
• IIS 5.0, Windows 2000
• IIS 5.1, Windows XP Professional and Windows XP Media Center Edition (requires retail CD)
• IIS 6.0, Windows Server 2003 and Windows XP Professional x64 Edition
• IIS 7.0, Windows Server 2008 and Windows Vista (Home Premium, Business, Enterprise and Ultimate editions)
• IIS 7.5, Windows Server 2008 R2 and Windows 7 (Home Premium, Professional, Enterprise and Ultimate editions)

Usage

As of October 2011^[update], IIS is the second most used server in the world, after Apache HTTP Server. It is used on 15.66% of servers and responds to 12.46% of total requests.^[11]

Security

Earlier versions of IIS were hit with a number of vulnerabilities, especially the CA-2001-13 which led to the infamous Code Red worm;^[12] however, both versions 6.0 and 7.0 currently have no reported issues with this specific vulnerability.^[13][14] In IIS 6.0 Microsoft opted to change the behaviour of pre-installed ISAPI handlers,^[15] 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.

In the current release, IIS 7, the components are provided as modules so that only the required components have to be installed, thus further reducing the attack surface. In addition, security features are added such as Request Filtering, which rejects suspicious URLs based on a user-defined rule set.^[16]

By default IIS 5.1 and lower run websites in-process under the SYSTEM account,^[17] 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.^[18] 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.^[19]

According to Secunia, as of June 2011^[update], IIS 7 had a total of 6 resolved vulnerabilities while^[14] IIS 6 had a total of 11 vulnerabilities out of which 1 was still unpatched. The unpatched security advisory has a severity rating of 2 out of 5.^[13]

In June 2007, a Google study of 80 million domains concluded that while the IIS market share was 23% at the time, IIS servers hosted 49% of the worlds malware, same as Apache servers whose market share was 66%. The study also observed the geographical location of these dirty servers and suggested that the cause of this could be the use of pirated copies of Windows for which security updates were unavailable.^[20] This is no longer the case: Microsoft supplies security updates to all users.^[21][22]

Features

The architecture of IIS 7 is modular. Modules, also called extensions, can be added or removed individually so that only modules required for specific functionality have to be installed. IIS 7 includes native modules as part of the full installation. These modules are individual features that the server uses to process requests and include the following:^[23]

• HTTP modules – Used to perform tasks specific to HTTP in the request-processing pipeline, such as responding to information and inquiries sent in client headers, returning HTTP errors, and redirecting requests.
• Security modules – Used to perform tasks related to security in the request-processing pipeline, such as specifying authentication schemes, performing URL authorization, and filtering requests.
• Content modules – Used to perform tasks related to content in the request-processing pipeline, such as processing requests for static files, returning a default page when a client does not specify a resource in a request, and listing the contents of a directory.
• Compression modules – Used to perform tasks related to compression in the request-processing pipeline, such as compressing responses, applying Gzip compression transfer coding to responses, and performing pre-compression of static content.
• Caching modules – Used to perform tasks related to caching in the request-processing pipeline, such as storing processed information in memory on the server and using cached content in subsequent requests for the same resource.
• Logging and Diagnostics modules – Used to perform tasks related to logging and diagnostics in the request-processing pipeline, such as passing information and processing status to HTTP.sys for logging, reporting events, and tracking requests currently executing in worker processes.

IIS 6.0 and higher support the following authentication mechanisms:^[24]

• Anonymous authentication
• Basic access authentication
• Digest access authentication
• Integrated Windows Authentication
• UNC authentication
• .NET Passport Authentication (Removed in Windows Server 2008 and IIS 7.0)^[25]
• Certificate authentication

IIS 7.5 includes the following additional or enhanced security features:^[26]

• Client Certificate Mapping
• IP Security
• Request Filtering
• URL Authorization

Authentication changed slightly between IIS 6.0 and IIS 7, 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". Notably, in IIS 7, each authentication mechanism is isolated into its own module and can be installed or uninstalled.^[25]

IIS Express

IIS Express, a lightweight version of IIS, is available as a standalone freeware server and may be installed on Windows XP with Service Pack 3 and subsequent versions of Microsoft Windows. IIS 7.5 Express supports only the HTTP and HTTPS protocols.^[27] IIS Express can be downloaded separately^[28] or as a part of Microsoft WebMatrix.^[29]

Extensions

IIS releases new feature modules between major version releases to add new functionality. The following extensions are available for IIS 7.5:

• FTP Publishing Service – Lets Web content creators publish content securely to IIS 7 Web servers with SSL-based authentication and data transfer.^[30]
• Administration Pack – Adds administration UI support for management features in IIS 7, including ASP.NET authorization, custom errors, FastCGI configuration, and request filtering.^[31]
• Application Request Routing – Provides a proxy-based routing module that forwards HTTP requests to content servers based on HTTP headers, server variables, and load balance algorithms.^[32]
• Database Manager – Allows easy management of local and remote databases from within IIS Manager.^[33]
• Media Services – Integrates a media delivery platform with IIS to manage and administer delivery of rich media and other Web content.^[34]
• URL Rewrite Module – Provides a rule-based rewriting mechanism for changing request URLs before they are processed by the Web server.^[35]
• WebDAV – Lets Web authors publish content securely to IIS 7 Web servers, and lets Web administrators and hosters manage WebDAV settings using IIS 7 management and configuration tools.^[36]
• Web Deployment Tool – Synchronizes IIS 6.0 and IIS 7 servers, migrates an IIS 6.0 server to IIS 7, and deploys Web applications to an IIS 7 server.^[37]

See also

IIS topics IIS Metabase LogParser Microsoft Personal Web Server Windows Activation Services

Similar servers Comparison of web servers List of FTP server software List of mail servers

References

1. ^ "Windows NT Internet Servers". Microsoft. July 10, 2002. http://support.microsoft.com/kb/120734. Retrieved 2008-05-26. 
2. ^ Kramer, Dave (December 24, 1999). "A Brief History of Microsoft on the Web". Microsoft corporation. http://www.microsoft.com/misc/features/features_flshbk.htm. 
3. ^ "Microsoft ASP.NET 2.0 Next Stop on Microsoft Web Development Roadmap". http://www.directionsonmicrosoft.com/sample/DOMIS/update/2004/08aug/0804a2nsow.htm. 
4. ^ "Chapter 1 - Overview of Internet Information Services 5.0". http://technet.microsoft.com/en-us/library/bb742405.aspx. Retrieved 2010-10-25. 
5. ^ "Internet Information Services 5.1". http://www.microsoft.com/windowsxp/evaluation/features/iis.mspx. Retrieved 2007-07-20. 
6. ^ "IIS Answers - IIS5.1 on XP Pro". http://www.iisanswers.com/IIS51.htm. Retrieved 2010-10-25. 
7. ^ "What's New In IIS 6.0?". http://www.devx.com/webdev/Article/17085/. Retrieved 2010-11-25. 
8. ^ "IIS 7.0: Explore The Web Server For Windows Vista and Beyond". http://msdn.microsoft.com/en-us/magazine/cc163453.aspx. Retrieved 2010-11-25. 
9. ^ "What's New in Web Server (IIS) Role in Windows 2008 R2". http://technet.microsoft.com/en-us/library/dd560629(WS.10).aspx. Retrieved 2010-11-25. 
10. ^ Release notes on SP2 CD.
11. ^ "October 2011 Web Server Survey". Netcraft. Netcraft Ltd.. 6 October 2011. http://news.netcraft.com/archives/2011/10/06/october-2011-web-server-survey.html. Retrieved 15 October 2011. 
12. ^ "CA-2001-13 Buffer Overflow In IIS Indexing Service DLL". CERT® Advisory. Computer emergency response team. 17 January 2002. http://www.cert.org/advisories/CA-2001-13.html. Retrieved 1 July 2011. 
13. ^ ^{a b} "Vulnerability Report: Microsoft Internet Information Services (IIS) 6". Secunia. Secunia ApS. http://secunia.com/advisories/product/1438/?task=statistics. Retrieved 1 July 2011. 
14. ^ ^{a b} "Vulnerability Report: Microsoft Internet Information Services (IIS) 7.x". Secunia. Secunia ApS. http://secunia.com/advisories/product/17543/?task=statistics. Retrieved 1 July 2011. 
15. ^ "IIS Installs in a Locked-Down Mode (IIS 6.0)". Microsoft Developer Network (MSDN). Microsoft Corporation. http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/54257c42-d723-4b12-badf-f4902c195821.mspx?mfr=true. Retrieved 1 July 2011. 
16. ^ Kenneth, Schaefer (2011). "Core Server". Professional IIS 7. Hoboken, New Jersey: John Wiley and Sons. ISBN 9781118058558. 
17. ^ "How To: Run Applications Not in the Context of the System Account in IIS (Revision 5.1)". Microsoft Support. Microsoft Corporation. 7 July 2008. Default Installation. http://support.microsoft.com/kb/319067/. Retrieved 20 July 2007. 
18. ^ Henrickson, Hethe; Hofmann, Scott R. (2003). "Chapter 15: ASP.NET Web Services". IIS 6: the complete reference. New York City: McGraw-Hill Professional. p. 482. ISBN 9780072224955. 
19. ^ Henrickson, Hethe; Hofmann, Scott R. (2003). "Chapter 1: IIS Fundamentals". IIS 6: the complete reference. New York City: McGraw-Hill Professional. p. 17. ISBN 9780072224955. 
20. ^ "Web Server Software and Malware". http://googleonlinesecurity.blogspot.com/2007/06/web-server-software-and-malware.html. 
21. ^ "Windows Pirates Encouraged to Install Security Updates". Technology Live (USA Today). February 2010. http://content.usatoday.com/communities/technologylive/post/2010/02/windows-pirates-encouraged-to-install-security-updates/1. Retrieved 18 July 2011. 
22. ^ Cooke, Paul (27 April 2009). "Who Gets Windows Security Updates?". Windows Security Blog. Microsoft Corporation. http://windowsteamblog.com/windows/b/windowssecurity/archive/2009/04/27/who-gets-windows-security-updates.aspx. Retrieved 18 July 2011. 
23. ^ Templin, Reagan (11 August 2010). "Introduction to IIS 7 Architecture". IIS.net. Microsoft Corporation. IIS 7 Modules. http://learn.iis.net/page.aspx/101/introduction-to-iis-7-architecture/. Retrieved 16 July 2011. 
24. ^ "Authentication Methods Supported in IIS 6.0 (IIS 6.0)". IIS 6.0 Documentation. Microsoft corporation. http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/523ae943-5e6a-4200-9103-9808baa00157.mspx?mfr=true. Retrieved 13 July 2011. 
25. ^ ^{a b} "Changes Between IIS 6.0 and IIS 7 Security". IIS.net. Microsoft Corporation. 7 February 2010. http://learn.iis.net/page.aspx/110/changes-between-iis-60-and-iis-7-security/. Retrieved 13 July 2011. 
26. ^ "Available Web Server (IIS) Role Services in IIS 7.5". Microsoft TechNet. Microsoft Corporation. http://technet.microsoft.com/en-us/library/cc753473.aspx. Retrieved 13 July 2011. 
27. ^ "IIS Express FAQ". The Official Microsoft IIS Site. Microsoft corporation. January 14, 2011. http://learn.iis.net/page.aspx/901/iis-express-faq/. Retrieved January 27, 2011. 
28. ^ "Download details: Internet Information Services (IIS) 7.5 Express". Microsoft Download Center. Microsoft corporation. January 10, 2011. http://www.microsoft.com/downloads/en/details.aspx?FamilyID=abc59783-89de-4adc-b770-0a720bb21deb. Retrieved January 27, 2011. 
29. ^ "IIS Express Overview". The Official Microsoft IIS Site. Microsoft corporation. January 14, 2011. http://learn.iis.net/page.aspx/868/iis-express-overview/. Retrieved January 27, 2011. 
30. ^ "FTP Publishing Service". IIS.net. Microsoft Corporation. http://www.iis.net/download/FTP. Retrieved 17 July 2011. 
31. ^ "Administration Pack". IIS.net. Microsoft Corporation. http://www.iis.net/download/AdministrationPack. Retrieved 17 July 2011. 
32. ^ "Application Request Routing". IIS.net. Microsoft Corporation. http://www.iis.net/download/ApplicationRequestRouting. Retrieved 17 July 2011. 
33. ^ "Database Manager". IIS.net. Microsoft Corporation. http://www.iis.net/download/DatabaseManager. Retrieved 17 July 2011. 
34. ^ "IIS Media Services". IIS.net. Microsoft Corporation. http://www.iis.net/media. Retrieved 30 July 2011. 
35. ^ "URL Rewrite". IIS.net. Microsoft Corporation. http://www.iis.net/download/URLRewrite. Retrieved 17 July 2011. 
36. ^ "WebDAV Extension". IIS.net. Microsoft Corporation. http://www.iis.net/download/webDAV. Retrieved 17 July 2011. 
37. ^ "Web Deploy 2.0". IIS.net. Microsoft Corporation. http://www.iis.net/download/webdeployq. Retrieved 17 July 2011. 

External links

• IIS.NET – The Official Microsoft IIS Site
• IIS 7.5 Product Page – Windows Server 2008 R2
• Security Guidance for IIS – Microsoft TechNet
• Microsoft Web Platform Installer – A free tool to install IIS and other components of the Microsoft Web Platform
• Microsoft WebsiteSpark Program – A program that offers IIS and other Microsoft Web Platform products at no upfront cost for 3 years