Onnowpurbo: /* External links */

2011-03-26T01:50:01Z

External links

← Older revision		Revision as of 01:50, 26 March 2011
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	* [http://support.microsoft.com/kb/172218 Microsoft TCP/IP Host Name Resolution Order]		* [http://support.microsoft.com/kb/172218 Microsoft TCP/IP Host Name Resolution Order]
	* [http://www.mvps.org/winhelp2002/hosts.htm MVPS.org "Blocking Unwanted Parasites with a Hosts File"]		* [http://www.mvps.org/winhelp2002/hosts.htm MVPS.org "Blocking Unwanted Parasites with a Hosts File"]

			==Pranala Menarik==

			* [[hosts: mesin penting]]

Onnowpurbo at 01:48, 26 March 2011

2011-03-26T01:48:38Z

← Older revision		Revision as of 01:48, 26 March 2011
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	The location of the hosts file in the [[file system]] hierarchy of operating systems varies.		The location of the hosts file in the [[file system]] hierarchy of operating systems varies.

	{\| ~~class~~="~~wikitable~~"		{\| border="1" cellpadding=2 style="border-collapse: collapse"
	\|-		\|-
	! Operating System		! Operating System

Onnowpurbo: New page: The '''hosts file''' is a computer file used in an operating system to map hostnames to IP addresses. The hosts file is a plain-text file and is traditionally named ''host...

2011-03-26T01:47:57Z

New page: The '''hosts file''' is a computer file used in an operating system to map hostnames to IP addresses. The hosts file is a plain-text file and is traditionally named ''host...

New page

The '''hosts file''' is a [[computer file]] used in an operating system to map [[hostname]]s to [[IP address]]es. The hosts file is a [[plain-text]] file and is traditionally named ''hosts''.

==Purpose==
The hosts file is one of several system facilities to assist in addressing network nodes in a computer network. It is a common part in a operating system's [[Internet Protocol]] (IP) implementation, and serves the function of translating human-friendly hostnames into numeric protocol addresses, called [[IP address]]es, that identify and locate a host in an IP network.

In some operating systems, the host file content is used preferentially over other methods, such as the [[Domain Name System]] (DNS), but many systems implement [[name service]] switches (.e.g., [[nsswitch.conf]]) to provide customization. Unlike the DNS, the hosts file is under the direct control of the local computer's administrator.

==File content==
The hosts file contains lines of text consisting of an IP address in the first text field followed by one or more hostnames, each field separated by white space (blanks or tabulation characters). Comment lines may be included; they are indicated by a hash character (#) in the first position of such lines. Entirely blank lines in the file are ignored. For example a typical hosts file may contain the following:
<pre>
#This is an example of the hosts file
127.0.0.1 localhost loopback
::1 localhost
</pre>
This example only contains entries for the loopback addresses of the system and their hostnames, a typical default content of the host file. The example illustrates that an
IP address may have multiple hostnames, and that a hostname may be mapped to several IP addresses.

==Location in the file system==
The location of the hosts file in the [[file system]] hierarchy of operating systems varies.

{| class="wikitable"
|-
! Operating System
! Version(s)
! Location
|-
| [[Unix]], [[Unix-like]], [[POSIX]]
|
| <code>/etc/hosts</code>
|-
|rowspan="4" |[[Microsoft Windows]]
| [[Windows 3.1x|3.1]]
| <code>%Windir%\HOSTS.SAM
|-
| [[Windows 95|95]], [[Windows 98|98/98SE]], [[Windows Me|Me]]
| <code>%WinDir%\</code>
|-
| [[Windows NT|NT]], [[Windows 2000|2000]], and 32-bit versions of [[Windows XP|XP]], [[Windows Server 2003|2003]], [[Windows Vista|Vista]], [[Windows 7|7]]
| <code>[[Environment variable#System path variables|%SystemRoot%]]\system32\drivers\etc\</code>
|-
| 64-bit versions
| <code>[[Environment variable#System path variables|%SystemRoot%]]\system32\drivers\etc\</code> (Many sources, including several Microsoft support pages, will incorrectly state that the hosts file is at <code>[[Environment variable#System path variables|%SystemRoot%]]\SysWOW64\drivers\etc\)
|-
| [[Windows Mobile]]
|
| Registry key under <code>\HKEY_LOCAL_MACHINE\Comm\Tcpip\Hosts</code>
|-
|rowspan="3" | Apple [[Macintosh]]
| 9 and earlier
| System Folder: Preferences or System folder
|-
| [[Mac OS X]] 10.0 – 10.1.5
| (Added through NetInfo or niload)
|-
| [[Mac OS X]] 10.2 and newer, [[iOS (Apple)|iOS]]
| <code>/private/etc/hosts</code> or, since <code>/etc</code> is a [[symbolic link]] to <code>/private/etc</code>, <code>/etc/hosts</code> (just like POSIX)
|-
| [[Novell NetWare]]
|
| <code>SYS:etc\hosts</code>
|-
| [[OS/2]] & [[eComStation]]
|
| <code>"bootdrive":\mptn\etc\</code>
|-
| rowspan="2"| [[Symbian OS|Symbian]]
| Symbian OS 6.1–9.0
| <code>C:\system\data\hosts</code>
|-
| Symbian OS [[Symbian OS#Symbian OS 9.1|9.1+]]
| <code>C:\private\10000882\hosts</code>
|-
| [[MorphOS]]
| NetStack
| <code>ENVARC:sys/net/hosts</code>
|-
| [[Android (operating system)|Android]]
|
| <code>/system/etc/hosts</code>
|-
| [[IOS (Apple)|iOS]]
| iOS 2.0 and newer
| <code>/etc/hosts</code>
|}

==History==
The [[ARPANET]], the predecessor of the [[Internet]], had no distributed host name database. Each network node maintained its own map of the network nodes as needed and assigned them names that were memorable to the users of the system. There was no method for ensuring that all references to a given node in a network were using the same name, nor was there a way to read the hosts file of another computer to automatically obtain a copy.

The small size of the ARPANET kept the administrative overhead small to maintain an accurate hosts file. Network nodes typically had one address and could have many names. As local area [[TCP/IP]] computer networks gained popularity, however, the maintenance of hosts files became a larger burden on system administrators as networks and network nodes were being added to the system with increasing frequency.

Standardization efforts, such as the format specification of the file ''HOSTS.TXT'' in RFC 952, and distribution protocols, e.g., the hostname server described in RFC 953, helped with these problems, but the centralized and monolithic nature of host files eventually necessitated the creation of the distributed [[Domain Name System]].

==Extended applications==
In its function of resolving host names, the hosts file may be used to define any [[hostname]] or [[domain name]] for use in the local system. This may be used either beneficially or maliciously for various effects.
;Redirecting local domains: Some web service and [[intranet]] developers and administrators define locally defined domains in a [[LAN]] for various purposes, such as accessing the company's internal resources or to test local websites in development.
;Internet resource blocking: Specially crafted entries in the hosts file may be used to block [[online advertising]], or the domains of known malicious resources and servers that contain [[spyware]], [[adware]], and other [[malware]]. This may be achieved by adding entries for those sites to redirect requests to another address that does not exist or to a harmless destination.

Various software applications exist that populate the hosts file with entries of undesirable Internet resources automatically.

==Security issues==
Because of its role in local name resolution, the hosts file represents an attack vector for malicious software. The file may be ''hijacked'', for example, by [[adware]], [[computer virus]]es, [[trojan horse (computing)|trojan horse]] software, and may be modified to redirect traffic from the intended destination to sites hosting content that may be offensive or intrusive to the user or the user’s computer system.The widespread [[computer worm]] [[Mydoom.B]] blocked users from visiting sites about [[computer security]] and [[antivirus software]] and also affected users' ability to access the Microsoft [[Windows Update]] website.

==See also==
* [[resolv.conf]]

==External links==
* [http://www.microsoft.com/technet/prodtechnol/windows2000serv/reskit/prork/prcc_tcp_lesj.mspx?mfr=true TCP/IP in Windows 2000 Professional]
* [http://support.microsoft.com/kb/172218 Microsoft TCP/IP Host Name Resolution Order]
* [http://www.mvps.org/winhelp2002/hosts.htm MVPS.org "Blocking Unwanted Parasites with a Hosts File"]

Hosts file - Revision history

Onnowpurbo: /* External links */

Onnowpurbo at 01:48, 26 March 2011

Onnowpurbo: New page: The '''hosts file''' is a computer file used in an operating system to map hostnames to IP addresses. The hosts file is a plain-text file and is traditionally named ''host...