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In computing, a server is a computer program or a device that provides functionality for other programs or devices, called “clients”. This architecture is called the client–server model, and a single overall computation is distributed across multiple processes or devices. Servers can provide various functionalities, often called “services”, such as sharing data or resources among multiple clients, or performing computation for a client. A single server can serve multiple clients, and a single client can use multiple servers. A client process may run on the same device or may connect over a network to a server on a different device.[1] Typical servers are database servers, file servers, mail servers, print servers, web servers, game servers, and application servers.[2]

Client–server systems are today most frequently implemented by (and often identified with) the request–response model: a client sends a request to the server, which performs some action and sends a response back to the client, typically with a result or acknowledgement. Designating a computer as “server-class hardware” implies that it is specialized for running servers on it. This often implies that it is more powerful and reliable than standard personal computers, but alternatively, large computing clusters may be composed of many relatively simple, replaceable server components.

The use of the word server in computing comes from queuing theory,[3] where it dates to the mid 20th century, being notably used in Kendall (1953) (along with “service”), the paper that introduced Kendall’s notation. In earlier papers, such as the Erlang (1909), more concrete terms such as “[telephone] operators” are used.

In computing, “server” dates at least to RFC 5 (1969),[4] one of the earliest documents describing ARPANET (the predecessor of Internet), and is contrasted with “user”, distinguishing two types of host: “server-host” and “user-host”. The use of “serving” also dates to early documents, such as RFC 4,[5] contrasting “serving-host” with “using-host”.

The Jargon File defines “server” in the common sense of a process performing service for requests, usually remote, with the 1981 (1.1.0) version reading:

SERVER n. A kind of DAEMON which performs a service for the requester, which often runs on a computer other than the one on which the server runs.

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Windows Server

Windows VPS is a brand name for a group of server operating systems released by Microsoft. It includes all Windows operating systems branded “Windows Server”, but not any other Microsoft product. The first Windows server edition to be released under that brand was Windows Server 2003. However, the first server edition of Windows was Windows NT 3.1 Advanced Server, followed by Windows NT 3.5 Server, Windows NT 4.0 Server, and Windows 2000 Server; the latter was the first server edition to include Active Directory, DNS Server, DHCP Server, Group Policy, as well as many other popular features used today.

This brand includes the following operating systems:[1][2]

  • Windows Server 2003 (April 2003)
  • Windows Server 2003 R2 (December 2005)
  • Windows Server 2008 (February 2008)
  • Windows Server 2008 R2 (July 2009)
  • Windows Server 2012 (August 2012)
  • Windows Server 2012 R2 (October 2013)
  • Windows Server 2016 (upcoming).

Microsoft has also produced Windows Server Essentials (formerly Windows Small Business Server) and Windows Essential Business Server (discontinued), software bundles which includes a Windows Server operating system and some other Microsoft Servers products.

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آموزش نصب IIS در ویندوز 2003

برای نصب وب سرور  IIS در ویندوز 2003 مراحل زیر را انجام دهید.

1.بر روی Start کلیک کرده و  Control Panel  را کلیک نمایید

2.Add or Remove Programs  را کلیک کرده و در صفحه باز شده Add/Remove Windows Components را کلیک نمایید

3.در صفحه باز شده Application Server را انتخاب کرده و گزینه Next را کلیک نمایید .

4.بعد از به پایان رسیدن مراحل نصب Finish را کلیک نمایید .

منبع ‌: سرور مجازی

file & folder permissions In Linux

The Unix files access is controlled. There are three types of access (permissions):

  • read
  • write
  • execute

Each file belongs to a specific user and group (ownership).

Access to the files is controlled by user, group, and what is called other/everyone permission bits and is usually set using a numerical value.

For example, 644 as permission bit will result in:

Owner / User Group Other/ Everyone 644

Each number represents the access level and it can be from 0 to 7.

The access level, depending on the number is as follows:

  • 0 – no access to the file whatsoever
  • 1 – execute permissions only
  • 2 – write permissions only
  • 3 – write and execute permissions
  • 4 – read permissions only
  • 5 – read and execute permissions
  • 6 – read and write permissions
  • 7 – read, write and execute permissions (full permissions)

Thus the above 644 permissions example will look like this:

Owner / User – Read and Write Group – Read and Write Other/ Everyone – Read only

To allow a script to be executed and read by everyone but the only one who can write in it is your user, you would need to set 755 as permissions:

  • Owner / UserGroupOther/ Everyone
  • 7 – Full permissions
  • 5 – read and execute
  • 5 – read and execute

Changing the permissions to 700 will make the file visible only for your username and no one else and setting it to 444 will allow only the file creator to modify it.

The command you need to issue to actually change the permissions is called ‘chmod’ and it generally looks like this:

chmod 755 configuration.php

The above example changes the permissions of configuration.php file and sets them to 755.

You can recursively change the permissions of all folders and files using the recursive argument:

chmod -R 755 *This will modify the permissions of all files in the current folder and
set them to 755.

You might wonder what the above user/group values are. These two settings are the actual ownership flags for a file or a folder.

Each file has a primary user that owns it and a group assigned to it. To change those values, a special command exists — ‘chown’.

Its syntax is very easy:

chown user: group file

For example:

Chown user:

siteground configuration.php

The above line will set the owner of the file to ‘user’ and the group to ‘siteground’.

Changing ownership recursively is also permitted and the flag (naturally) is -R: chown -R user: siteground *

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