Андрей Смирнов
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Диагностика и логи

How to enable Telnet Server for Windows 10

Telnet clients let you connect to other Telnet Servers. You cannot connect to your own system and fire remote commands. For that, you need a Telnet Server and unfortunately, there is no native way to enable it in Windows 10. You have to install third-party apps to start serving Telnet on port 23.

My two favorite utilities to do so are HK Telnet Server and KpyM Telnet Server. Both of them serve a different audience.

If all you want is to enable the telnet server to fire remote commands to your machine, I would suggest HK Telnet server. It is pretty easy to set up. Simply, download the app and launch the application. It is more of like a portable app rather than an exe. As soon, as you launch the application, you get a floating window.

Here, you can enter the port number where you want Telnet to accept the connections from. The UI is pretty simple with minimum options. You can set a user ID and password for the telnet login.

The app doesn’t provide an option to force SSL or encryption. If you want a bigger solution with SSH like custom login message and IP blocking then you need to get on KpyM Telnet Server. During the installation of the app, you will be prompted to start the server either at port 22 (SSH) or port 23 (telnet). In case, you are going to run telnet choose port 23 now because this is the only time you will be seeing GUI in this app.

Once you have finished installing it, you can configure further through the KTS daemon. Go to the Start menu and type “Setup kpyM Telnet SSH Server“. This will open a black dialogue box where you can configure settings like use SSL, port number, login_message, password etc. The same daemon also provides the options to start or stop the telnet server.

Closing Words

Security was one of the major concerns due to which Telnet Server was removed from Windows. It is advisable not to use telnet when you are dealing with sensitive data. However, in the case of public servers, it is okay if you don’t want to set up encryption key certificates and SSL.

Voice out your queries in the comments and I will be happy to help you out.

Also Read: 6 Best Android SSH Client You Should Try

How to Check if a Port is Open on Mac

High Sierra users: Apple removed telnet client from macOS 10.13 High Sierra. There is no official way to return it, but you can still copy it from an older OS or compile from sources and use on High Sierra. See more details here and here.

Just like on Windows, telnet can be accessed through Terminal, the command prompt on macOS. To open telnet, click “Go” > “Utilities” > «Terminal», then run the following command (the numbers are example IP address and port): telnet , e.g.>telnet 443

When a computer port is open a blank screen will show up, meaning that the connection has been successful. An unsuccessful connection will be accompanied by an error message. 

An alternative to telnet in checking ports is Network Utility. In order to check ports on a Mac, follow the plan below:

Open «Network Utility» > Click «Port Scan» > Indicate the hostname and ports to scan the remote host e.g. myserver.com from 995 to 995 > Check the output 

What is Telnet and how does it work?

Telnet is an Internet protocol that allows you to connect to a different computer on your local network or on the Internet.

Telnet was invented in 1969, and it’s often considered an ancestor of modern Internet.

Today most users use a graphical user interface, but when Telnet was invented there were no browsers or graphical operating systems. Therefore, users had to rely solely on command line interface.

It’s worth mentioning that Telnet still works like it did decades ago, and Telnet clients are available for almost any platform.

Telnet changed the way how people use Internet because in the time before Telnet users had to manually use the server in order to get certain data.

With Telnet, users could access the server remotely from the comfort of their home for the first time.

In addition to remote access, multiple users were able to connect to the server over Telnet. Therefore, it’s not hard to see how Telnet influenced the development of the Internet.

We have to mention that there are two different terms when it comes to Telnet: Telnet server and Telnet client. The former is a computer designed to run as a Telnet server.

You can easily turn your Windows PC into a Telnet server and you should be able to access it over Telnet.

Bear in mind that having a public IP address leaves your computer open for access by any computer on the Internet, so be sure to use a firewall in order to protect your PC from unauthorized remote access.

READ ALSO: 7 best tabbed command line tools for Windows 10

Telnet client is a PC that uses a Telnet connection to connect to a Telnet server. In fact, you can use Telnet from Windows 10 by following these steps:

  1. Press Windows Key + S on your keyboard and enter features. Select Turn Windows Features on or off.
  2. When Windows Features opens, scroll down and check Telnet Client. Click OK to install Telnet.
  3. Wait until Windows installs the necessary components.
  4. Once the installation is completed click the Close button.

After you install Telnet, you can start it by doing the following:

  1. Press Windows Key + S and enter telnet. Select Telnet from the list of results.
  2. Command line will now open, and you should be able to use Telnet without any problems.

Why is Telnet obsolete?

Although running Telnet on Windows 10 is fairly simple, the question remains why would you use Telnet for? Telnet is an outdated protocol, and most people don’t use it anymore.

This protocol is great if you are a computer geek, and you want to access Internet by using command line. Unfortunately, there aren’t many Telnet servers available nowadays, so you might have to do some research before you find one.

One of the biggest flaws of Telnet is its lack of security. Telnet transmits all the data between the client and the server without any encryption which means that almost anyone can intercept your data.

This is especially important if you’re sending sensitive information over Telnet, such as your username or password. Due to lack of encryption, malicious users can easily steal your password and see all the data between the Telnet client and server.

Also, Telnet doesn’t have authentication, which means that malicious users can easily intercept your traffic. Lastly, Telnet has several additional security vulnerabilities which make it quite unsafe to use.

Even though Telnet in Windows 10 might not be the safest Internet protocol, newer protocols, such as SSH for example, were inspired by Telnet. They are designed to fix many flaws that original Telnet had.

Telnet might not be as popular as it was a few decades ago. Stll, it’s certain that Telnet changed the way how Internet works forever.


  • How to protect your Windows 10 device on public Wi-Fi network
  • Fix: Network Protocol Missing in Windows 10
  • Fix: Error ‘Err_ssl_protocol_error’ in Windows 8.1, 10
  • 4 best bandwidth monitors for Windows 10
  • How to fix Ethernet problems in Windows 10

Editor’s Note: This post was originally published in July 2016 and has been since updated for freshness, and accuracy.

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Telnet Client equals Terminal Emulator

A telnet-client is a computer that the user interacts with, while the
telnet-server processes the commands. The telnet-client is usually
a terminal emulator,
i.e. a software that allows a remote computer to receive keyboard input
from, and send formatted text to the user’s computer.

ZOC is the
telnet client that can handle all the basic terminal functions as
well as a wealth of additional, useful features. This telnet client takes
advantage of the computing power of a PC to allow you to automate tasks
(such as logging on or retrieving data automatically), log sessions on
screen or file (for documentation or later review), copy data between a
text processor and the remote server, and much more.

Quick start

'use strict'constTelnet=require('telnet-client')asyncfunctionrun(){let connection =newTelnet()let params ={    host'',    port23,    shellPrompt'/ # ',    timeout1500}try{awaitconnection.connect(params)}catch(error){}let res =awaitconnection.exec('uptime')console.log('async result:', res)}run()
var Telnet =require('telnet-client')var connection =newTelnet()var params ={  host'',  port23,  shellPrompt'/ # ',  timeout1500,}connection.on('ready',function(prompt){connection.exec(cmd,function(err,response){console.log(response)})})connection.on('timeout',function(){console.log('socket timeout!')connection.end()})connection.on('close',function(){console.log('connection closed')})connection.connect(params)
var Telnet =require('telnet-client')var connection =newTelnet()var params ={  host'',  port23,  shellPrompt'/ # ',  timeout1500,}connection.connect(params).then(function(prompt){connection.exec(cmd).then(function(res){console.log('promises result:', res)})},function(error){console.log('promises reject:', error)}).catch(function(error){})
var co =require('co')var bluebird =require('bluebird')var Telnet =require('telnet-client')var connection =newTelnet()var params ={  host'',  port23,  shellPrompt'/ # ',  timeout1500,}co(function*(){try{yieldconnection.connect(params)}catch(error){}let res =yieldconnection.exec(cmd)console.log('coroutine result:', res)})bluebird.coroutine(function*(){try{yieldconnection.connect(params)}catch(error){}let res =yieldconnection.exec(cmd)console.log('coroutine result:', res)})()
'use strict'constPromise=require('bluebird')consttelnet=require('telnet-client')require('babel-runtime/core-js/promise').default=PromisePromise.onPossiblyUnhandledRejection(function(error){throw error})asyncfunctionrun(){let connection =newTelnet()let params ={    host'',    port23,    shellPrompt'/ # ',    timeout1500}try{awaitconnection.connect(params)}catch(error){}let res =awaitconnection.exec(cmd)console.log('async result:', res)}run()

Enabling telnet client in Microsoft Windows operating systems

One of the most important things to remember is that Telnet is disabled by default in Window’s settings, so you need to turn it on before you can do anything. Turning it on will help you to run the required diagnostics and check if a port is open. If you try to use telnet without turning it on first, you’ll receive a message like: 

In order to turn Telnet on, you need to use the command line or the graphical interface of your computer.

Enabling telnet client through Command Prompt:

If you want to enable Telnet via the command line, open the Command Prompt with elevated privileges (“as Administrator”) and run the following command:

Dism /Online /Enable-feature /FeatureName:TelnetClient

After you’ve put this in, Telnet will be ready to use to check your ports. 

Alternatively to Command Prompt, you can use the following PowerShell command to achieve the same result:

Install-WindowsFeature -name Telnet-Client

If you want to use the graphical user interface you need to: 

Windows 7, 8. 10:

Open Windows Start menu > Type «Control Panel» > Press Enter > “Programs” > «Programs and Features» > Turn Windows features on or off > Select «Telnet Client» > Press “OK»

Windows Server 2008:

Open “Server Manager” > Features > click “Add Features” > enable “Telnet Client” checkbox > click “Next” > click “Install” > when the feature installation finishes, click “Close”

Windows Server 2012, 2016:

Open “Server Manager” > “Add roles and features” > click “Next” until reaching the “Features” step > tick “Telnet Client” > click “Install” > when the feature installation finishes, click “Close”.

Не является внутренней или внешней командой – как исправить

Чтобы избавиться от ошибки «Не является внутренней или внешней командой» необходимо указать системе путь (по-английски – «path») к директориям, где находятся нужные нам файлы.

Для этого необходимо точно знать, где находятся данные файлы (к примеру, «javac» может находиться по пути С:Program FilesJavajdk (вместо «jdk» может быть «jdk» с другим числом). Необходимо скопировать указанный путь в буфер обмена (пометьте его курсором, а потом нажмите на сочетание клавиш Ctrl+C).

  1. Затем перейдите на рабочий стол ПК, наводите курсор на «Мой компьютер», нажмите на правую клавишу мыши, в появившемся меню выберите «Свойства».
  2. В открывшемся окне кликните на «Дополнительные параметры системы» слева, а затем на кнопку «Переменные среды».
  3. В «Системные переменные» ищете параметр «Path», и добавьте туда после точки с запятой скопированный вами ранее полный путь из директории Program FilesJava.
  4. Подтвердите изменения, нажав на «Ок», затем вновь откройте консоль, и наберите нужную команду (можете также перезагрузить систему для профилактики), ошибка может быть устранена.

Альтернативой может быть перенос не запускаемых файлов в известные системе директории (например, на общий корневой каталог ОС Виндовс, или в C:WindowsSystem32), обычно система работает с ними вполне корректно.


Также, в случае некоторых компонентов (например, «telnet») проблема с ними возникает по причине их отсутствия в системе, потому их необходимо доустановить.

  1. В случае с «telnet» это делается переходом в «Панель управления» — «Программы и компоненты» — «Включение или выключение компонентов Windows».
  2. Находим там «Клиент Telnet» ставим слева от него галочку, и нажимаете на «Ок».
  3. Программа будет установлена и функционал «telnet» должен работать корректно.

Telnet и POP3 получение почты

Попробуем получить почту с сервера POP3. С pop3 все относительно просто:

exim# telnet localhost 110
Trying ::1...
telnet: connect to address ::1: Connection refused
Connected to localhost.
Escape character is '^]'.
+OK Hello there.
-1> user test@exim.teachers
+OK Password required.
-2> pass pass
+OK logged in.
-3> list
+OK POP3 clients that break here, they violate STD53.
1 1953
2 337
-4> retr 1
+OK 1953 octets follow.
Return-path: <root@exim.teachers>
Envelope-to: test@exim.teachers
Delivery-date: Tue, 20 Feb 2007 18:46:12 +0300
Received: from root by mx.exim.teachers with local (Exim 4.66 (FreeBSD))
        (envelope-from <root@exim.teachers>)
        id 1HJXC0-000597-6r
        for test@exim.teachers; Tue, 20 Feb 2007 18:46:12 +0300
To: test@exim.teachers
Subject: test
Message-Id: <E1HJXC0-000597-6r@mx.exim.teachers>
From: Charlie Root <root@exim.teachers>
Date: Tue, 20 Feb 2007 18:46:12 +0300

# $FreeBSD: src/etc/master.passwd,v 1.40 2005/06/06 20:19:56 brooks Exp $
root:*:0:0:Charlie &:/root:/bin/csh
toor:*:0:0:Bourne-again Superuser:/root:
daemon:*:1:1:Owner of many system processes:/root:/usr/sbin/nologin
operator:*:2:5:System &:/:/usr/sbin/nologin
bin:*:3:7:Binaries Commands and Source:/:/usr/sbin/nologin
tty:*:4:65533:Tty Sandbox:/:/usr/sbin/nologin
kmem:*:5:65533:KMem Sandbox:/:/usr/sbin/nologin
games:*:7:13:Games pseudo-user:/usr/games:/usr/sbin/nologin
news:*:8:8:News Subsystem:/:/usr/sbin/nologin
man:*:9:9:Mister Man Pages:/usr/share/man:/usr/sbin/nologin
sshd:*:22:22:Secure Shell Daemon:/var/empty:/usr/sbin/nologin
smmsp:*:25:25:Sendmail Submission User:/var/spool/clientmqueue:/usr/sbin/nologin
mailnull:*:26:26:Sendmail Default User:/var/spool/mqueue:/usr/sbin/nologin
bind:*:53:53:Bind Sandbox:/:/usr/sbin/nologin
proxy:*:62:62:Packet Filter pseudo-user:/nonexistent:/usr/sbin/nologin
_pflogd:*:64:64:pflogd privsep user:/var/empty:/usr/sbin/nologin
_dhcp:*:65:65:dhcp programs:/var/empty:/usr/sbin/nologin
uucp:*:66:66:UUCP pseudo-user:/var/spool/uucppublic:/usr/local/libexec/uucp/uucico
pop:*:68:6:Post Office Owner:/nonexistent:/usr/sbin/nologin
www:*:80:80:World Wide Web Owner:/nonexistent:/usr/sbin/nologin
nobody:*:65534:65534:Unprivileged user:/nonexistent:/usr/sbin/nologin
clamav:*:106:106:Clam Antivirus:/nonexistent:/sbin/nologin
courier:*:465:465:Courier Mail System:/var/spool/courier:/sbin/nologin
-5> quit
+OK Bye-bye.
Connection closed by foreign host

Итак, описание по командам:

  1. Команда user указывает имя пользователя
  2. команда pass указывает пароль пользователя
  3. list выводит список всех сообщений, хранящихся на сервере
  4. retr заставляет сервер вывести сообщение. В качестве параметра передается номер сообщения, который выводится по команде List
  5. аналогично smtp команде

Activar Telnet Windows 10 de forma gráfica

Además de poder activar Telnet mediante comandos, también podremos hacerlo de forma gráfica. Es un poco más largo, pero seguramente lo memoricemos mejor. Procedamos:

Lo primero será acceder al menú inicio y escribir “Panel de control”. Una vez localizado este, daremos clic para acceder a él.

Para mayor comodidad recomendamos de elegir la vista del panel de configuración en modo iconos. Localizando el icono que pone “Programas y características” accederemos a él

Ahora pulsamos sobre la opción que aparece en el lateral que dice “Activar o desactivar las características de Windows”

Ahora buscaremos en la lista “Cliente Telnet” y activaremos su casilla

De esta forma tendremos activo el cliente Telnet para poderlo utilizar en el equipo.

How to enable Telnet Client in Windows 10

If you type in telnet in the command prompt you will get an error stating “Telnet is not recognized as an internal or external command.”. This is because telnet client is disabled in Windows 10 by default. To enable Telnet, go to the start menu and type “Turn Windows features on and off“.

On the next pop-up, browse to Telnet Client. Click the checkbox beside it and hit Ok.

Windows will take some time to install Telnet and once done, you can use the telnet command in CMD or you can fire the telnet utility from the search menu. To do that, press Win+S and type Telnet.

This will open the telnet client directly within CMD and the window should look like the one below.

Telnet и HTTP: получение HEAD

Telnet и получение HEAD HTTP запрос запроса протокола Методы и структура протокола HTTP.

Проверка Кода Состояния HTTP с помощью Telnet.

$ telnet СЕРВЕР ПОРТ
Trying xxx.xxx.xxx.xxx...
Connected to СЕРВЕР.
Escape character is '^]'.
<Нажмите ENTER>


telnet> open websl.biz 80
Connected to websl.biz.
Escape character is '^]'.
HOST: websl.biz
HTTP1.1 200 OK
Cache-Control: private
Content-Length: 5825
Content-Type: texthtml; charset=utf-8
Server: Microsoft-IIS7.5
X-AspNetMvc-Version: 3.0
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
Date: Mon, 28 Jan 2013 21:25:15 GMT

How Does Telnet Work?

Telnet originally was used on terminals. These computers require only a keyboard because everything on the screen displays as text. The terminal provides a way to remotely log on to another device, just as if you were sitting in front of it and using it like any other computer.

Nowadays, Telnet can be used from a virtual terminal, or a terminal emulator, which is essentially a modern computer that communicates with the same Telnet protocol. One example of this is the telnet command, available from the Command Prompt in Windows. The telnet command uses the Telnet protocol to communicate with a remote device or system.

Telnet commands can also be executed on other operating systems such as Linux and macOS, in the same way that telnet commands are executed in Windows.

Telnet isn’t the same as other TCP/IP protocols such as HTTP, which transfers files to and from a server. Instead, the Telnet protocol has you log on to a server as if you were an actual user, then grants you direct control and all the same rights to files and applications as the user that you’re logged in as.

Although not the same as Telnet, if you’re looking for a way to communicate with another computer remotely, see this list of free remote access programs.

Interpret-as-Command (IAC)

Interpret as Command

The client and server use this character to manage the connection or transmit data that
is not intended for the user, e.g. the telnet client can use it to tell the server about
changes in screen size, or that it intends to transmit binary data.

All Telnet commands consist of at least a two byte sequence: the
«Interpret as Command» (IAC) escape character followed by the code
for the command. The commands dealing with option negotiation are
three byte sequences, the third byte being the code for the option
referenced. This format was chosen so that as more comprehensive use
of the «data space» is made, collisions of data bytes with reserved
command values will be minimized. With the chosen set-up, only the
IAC need be doubled to be sent as data, and the other 255 codes
may be passed transparently.

Some of the telnet commands (2nd byte in the data stream after IAC) are:

Enabling the Telnet Client

Firstly you need to enable the telnet client, if you don’t enable it you’ll get a result similar to the below message when trying to use it.

C:\>telnet google.com 80
'telnet' is not recognized as an internal or external command, operable program or batch file.

You can enable the telnet client either by command line or through the graphical interface.

Enabling the telnet client through command prompt

Using the command line is the easiest and fastest way to install the telnet client. Run the below command in command prompt with administrator permissions.

dism /online /Enable-Feature /FeatureName:TelnetClient

That’s it, after a few seconds telnet should be ready to use.

Enabling the telnet client through PowerShell

Again we can also do this instead with PowerShell, we can run the below command in a PowerShell console with administrator permissions.

Install-WindowsFeature -name Telnet-Client

Enabling the telnet client through the graphical user interface

  1. Open Server Manager.
  2. From Server Manager click “Add roles and features”.
  3. The Add Roles and Features Wizard opens to the Before you Begin screen, click next.
  4. On the Installation Type screen, leave Role-based or Feature-based installation selected and click next.
  5. On the server selection screen, select the server to install on. By default it should be the local server itself, click next.
  6. On the Server Roles screen, click next. We are installing a feature rather than a role so don’t select anything here.
  7. On the Features screen, tick the check box next to Telnet Client.
  8. On the Confirmation screen, click Install.
  9. Once the installation succeeds, click the Close button. The telnet client is now installed and ready for use.

Verifying that the telnet client is enabled

Simply open command prompt or powershell, type ‘telnet’ and press enter. If this was successful you should have a prompt similar to the below:

Welcome to Microsoft Telnet Client

Escape Character is 'CTRL+]'

Microsoft Telnet>

Already have telnet installed but still failing?
In some cases you must run command prompt or powershell as administrator in order to issue the telnet command, otherwise it will give the same error as if it was not enabled at all.

Limitaciones de Telnet en Windows 10

Debemos de tener en cuenta un aspecto muy importante de Telnet en Windows 10, y es que este sistema operativo no dispone de servidor de Telnet. La consecuencia de esto es la de que solamente podremos utilizar Windows como un equipo cliente de Telnet, pero en ningún caso podremos utilizarlo como un servidor para acceder a este.

En versiones anteriores del sistema operativo como Windows 7 o Windows Vista sí disponemos de servidor de telnet, y por supuesto en Windows Server.

También te recomendamos:

Como entrar en modo seguro Windows 10

El protocolo Telnet es en sí un sistema bastante inseguro de acceso remoto a equipos, por lo que Microsoft para su sistema de escritorio ha deshabilitado la posibilidad de convertirlo en servidor.

Execute Telnet Commands in Windows

Telnet commands are easy to execute. After opening Command Prompt, enter the word telnet. The result is a line that says Microsoft Telnet>, which is where Telnet commands are entered.

If you don’t plan to follow the first telnet command with additional commands, type telnet followed by any telnet command, such as the ones shown in the examples below.

To connect to a Telnet server, enter a command that follows this syntax:


For example, entering telnet textmmode.com 23 connects to textmmode.com on port 23 using Telnet.

The last portion of the command is used for the Telnet port number but is only necessary to specify if it’s not the default port of 23. For example, telnet textmmode.com 23 is the same as running the command telnet textmmode.com, but not the same as telnet textmmode.com 95, which connects to the same server but on port 95.

What is Telnet?

Telnet is often controlled via a terminal and is completely controlled via a keyboard. Unlike the actual computer, there is no graphical user interface or hardware like a mouse or any other pointing device. As explained earlier, the Telnet lets you remotely log in to another device and control it remotely. In other words, Telnet is more like a Team Viewer but for advanced functionalities.

It’s worth noting that Telnet and other TCP/IP protocols are completely different. Telnet lets you log in to a server and uses it like you are an actual user. As part of this, you will get the same rights as the user who has logged in to the server locally.

Why has Telnet usage decreased?

We need to realize that Telnet was conceived in a day and age when the internet was still at its infancy. The protocol, as such, offers zero encryption and thus is vulnerable to attacks. In the early days, this was not a big issue since, like the internet, the cyberattacks were not rampant. However, things have changed, and people have switched from Telnet to web interfaces for controlling devices remotely.

How to set up and use Telnet on Windows 10?

There are two ways of setting up Telnet; you can install it from the Windows Features section or from the command prompt. The method below shows the Control Panel method.

  • Type control in the Run prompt (Win +R), and press the Enter key to open Control Panel.
  • Select Program > Programs and Features > Turn Windows Features on and off.
  • In the checklist, click on the Telnet Client, and click on the Ok button to install it.

If you do not install Telnet this way and try to ruin it directly you will receive Telnet is not recognized as an internal or external command on Windows 10

To install, enable or disable Telnet using Command Prompt

dism /online /Enable-Feature /FeatureName:TelnetClient

Learn more about how to enable or disable Telnet using CMD.

Use Telnet via Command Prompts

Apart from playing chess, watching Starwars, you can use the following Telnet Commands.

c    - close                    close current connection
d    - display                  display operating parameters
o    - open hostname      connect to hostname (default port 23).
q    - quit                     exit telnet
set  - set                      set options (type 'set ?' for a list)
sen  - send                     send strings to server
st   - status                   print status information
u    - unset                    unset options (type 'unset ?' for a list)
?/h  - help                     print help information

Many of the commands have options. You can add /h at the end reveal more. You can use Telnet for simple things like checking the status of the HTTP server, and it allows unrestricted access to a controlled system’s resources if permission has been given. However, since it is not encrypted, it is not used keeping the security concerns in mind, and if someone has access to it on your computer, a lot of things can go wrong.

Wrapping it up

Telnet can also be a fun way to access stuff using commands. The tool in itself doesn’t come with a password. There are many Command Prompt tricks that can be performed on Telnet. Surprisingly one can also access weather and other information using Telnet. I hope the post was easy to follow, and you were able to install and use Telnet in Windows.

Tags: Features

Подведение итогов

Главной функцией протоколов TELNETи SSHявляется предоставление возможности входа в удаленную систему. Эта функция предоставляет практически неограниченные возможности использования этих протоколов:

üОни могут использоваться системными администраторами для удаленной настройки компьютеров некоторой сети, что позволит им выполнять свои непосредственные обязанности не вставая со своего рабочего места.


üОни могут использоваться для настройки различного рода сетевых служб, таких как сервер исходящей почты SMTP или сервер доменных имен DNS.

üОни могут использоваться для обмена файлами между компьютерами подключенными, например через модем.

üОни могут предложить пользователю возможность общения с сетевыми сервисами «вручную», что иногда бывает полезно для системных администраторов для отправки различных команд сетевым службам и последующего анализа полученных ответов.

Однако кардинальные различия между этими протоколами не могут остаться незамеченными. Отсутствие любого рода защиты передаваемых данных, а также системы аутентификации делает протокол TELNET весьма непривлекательным с точки зрения безопасности. Кроме того, на данный момент найдены уязвимости в протоколе SSH-1. Именно поэтому специалисты в области информационной и компьютерной безопасности настоятельно рекомендуют отказаться (по взможности) от использования этих протоколов.

В свою очередь, протокол SSH-2, предоставляя возможность защиты передаваемых данных путем использования стойкого алгоритма шифрования, системы аутентификации, системы контроля целостности данных и возможности сжатия, может предоставить дополнительную функциональность.

Все вышесказанное говорит в пользу того, что протокол TELNET может быть использован только в малых сетях при уверенности, что передаваемые данные никакой важности не несут. Возможности же протокола SSH почти неограниченные

Однако, необходимо отметить, что мир не стоит на месте. Развиваются технологии, Интернет растет, а вместе с ним растет и развивается сообщество хакеров. Будучи сегодня безопасной технологией, завтра SSH может быть под угрозой исчезновения, вследствие найденных в протоколе уязвимостей. Но даже если это случится, протоколы, обеспечивающие функционирование эмуляторов терминалов продолжат свое развитие под действием группы SECSH организации IETF. На сегодняшний же день можно с уверенности утверждать, что протокол SSH-2 предоставляет огромные возможности всем пользователям открытых информационных систем.


  1. http://en.wikipedia.org/
  2. http://www.cryptopro.ru/cryptopro/documentation/dig-cert.htm
  3. http://www.sgu.ruiecsitpglava21.htm
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