Telnet 0.13.0

dotnet add package Telnet --version 0.13.0                
NuGet\Install-Package Telnet -Version 0.13.0                
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="Telnet" Version="0.13.0" />                
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add Telnet --version 0.13.0                
#r "nuget: Telnet, 0.13.0"                
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install Telnet as a Cake Addin
#addin nuget:?package=Telnet&version=0.13.0

// Install Telnet as a Cake Tool
#tool nuget:?package=Telnet&version=0.13.0                

Build, Publish, Tag

Telnet

We needed to issue simple commands to (and monitor) a router remotely and that's what we've been able to achieve with this little library. It's usage is simple, it doesn't do anything particularly fancy but if all you're wanting to do is interact with a telnet server by issuing commands, parsing text responses and having the opportunity to respond in code accordingly then hopefully having taken the time to wrap this up in a simple NuGet package will make your life easier!

FYI I'm happy to take merge requests if they meet incumbent standards, don't break anything and accomodate the code file sharing so all versions work (and likely receive the same change). I'm no TCPIP/Telnet expert but if I can help out with bugs or feature requests I'll do what I can, outside my day job ofc!

Release Notes

v0.9 introduced a significant bump to Net versions and some potentially breaking code changes. Changes to your consuming code should be minimal, but be prepared to test thoroughly. Please raise an Issue if you encounter any problems; in part it'll help others with the same problems and we'll see what we can do to accomodate your use cases.

v0.10 introduced an unintended dependency that's removed as of 0.11.2.

Most common functions in C# NuGet

Depending on which version of this library you use, you may or may not have access to asynchronous functionality. Wherever possible we would recommend using the async overloads.

  • Client - var client = new Client(\<ip string>, \<port#>, new CancellationToken()));
    • Needed to setup the connection
  • TryLogin - bool result = await client.TryLoginAsync(\<username>, \<password>, \<Timout ms>, \<lineFeed default='\\n'>)
    • Most Telnet connections are required to login; this function handles that and lets you know if it was successful. Please note it is just a wrapper for Read and Write calls to cover the most common scenario. If it doesn't work, roll your own TerminatedReads and Writes to service your specific UseCase.
      • Try login uses a 'terminator' (the character after which you start writing commands) to detect if the login was successful (default is >). The terminator character is found after login and you can begin entering commands, for example, > configure - '>' is the terminator.
        If the terminator/linestarter is different to '>', you will need to specify it as a extra parameter. client.TryLoginAsync(\<username>, \<password>, \<Timout ms>, \<terminator>, \<lineFeed default='\\n'>)
  • TerminatedRead - string s = await client.TerminatedReadAsync(\<value>, \<Timeout ms>)
    • Will read until it sees the specified value (usually just use the terminator/> as the value to get started)
  • WriteLine - await client.WriteLineAsync(\<value>, \<Timeout ms>
    • Will write the value to the session

Debugging telnet connections

Wireshark is a good way to go about checking what is being sent back and forth - you can see the transmissions in plain text. Filter recording entries by 'telnet'.

Usage Examples:

.NET Fiddle https://dotnetfiddle.net/S9Ii6n

Asynchronous C#

    namespace PrimS.Telnet.CiTests
    {
      using System;
      using FluentAssertions;
      using System.Threading;
      using System.Threading.Tasks;
      using System.Text.RegularExpressions;
      using Xunit;

      public class ReadMeExampleFixture
      {
        public const string Pattern =
          "(?:WAN2 total TX: )([0-9.]*) " +
          "((?:[KMG]B)|(?:Bytes))" +
          "(?:[, ]*RX: )([0-9.]*) " +
          "((?:[KMG]B)|(?:Bytes))";
        private const int TimeoutMs = 5000;

        [Fact]
        public async Task ReadMeExample()
        {
          using (var server = new DummyTelnetServer())
          {
            using (var client = new Client(
              server.IPAddress.ToString(),
              server.Port,
              new CancellationToken()))
            {
              client.IsConnected.Should().Be(true);
              Client.IsWriteConsole = false;
              (await client.TryLoginAsync(
                "username",
                "password",
                TimeoutMs)).Should().Be(true);
              await client.WriteLineAsync("show statistic wan2");
              string s = await client.TerminatedReadAsync(
                ">",
                TimeSpan.FromMilliseconds(TimeoutMs));
              s.Should().Contain(">");
              s.Should().Contain("WAN2");
              var regEx = new Regex(Pattern);
              regEx.IsMatch(s).Should().Be(true);
              MatchCollection matches = regEx.Matches(s);
              matches.Count.Should().Be(1);
              matches[0].Captures.Count.Should().Be(1);
              matches[0].Groups.Count.Should().Be(5);
              matches[0].Groups[0].Value.Should().Be(
                "WAN2 total TX: 6.3 GB ,RX: 6.9 GB");
              matches[0].Groups[1].Value.Should().Be("6.3");
              matches[0].Groups[2].Value.Should().Be("GB");
              matches[0].Groups[3].Value.Should().Be("6.9");
              matches[0].Groups[4].Value.Should().Be("GB");
            }
          }
        }
      }
    }

Synchronous C#

    namespace PrimS.Telnet.CiTests
    {
      using FluentAssertions;
      using Xunit;
      using System;
      using System.Text.RegularExpressions;

      [TestClass]
      public class ReadMeExampleFixture
      {
        public const string Pattern =
          "(?:WAN2 total TX: )([0-9.]*) " +
          "((?:[KMG]B)|(?:Bytes))" +
          "(?:[, ]*RX: )([0-9.]*) " +
          "((?:[KMG]B)|(?:Bytes))";
        private const int TimeoutMs = 5000;

        [Fact]
        public void ReadMeExample()
        {
          using (var server = new DummyTelnetServer())
          {
            using (var client = new Client(
              server.IPAddress.ToString(),
              server.Port,
              new CancellationToken()))
            {
              client.IsConnected.Should().Be(true);
              Client.IsWriteConsole = false;
              client.TryLogin(
                "username",
                "password",
                TimeoutMs).Should().Be(true);
              client.WriteLine("show statistic wan2");
              string s = client.TerminatedRead(
                ">",
                TimeSpan.FromMilliseconds(TimeoutMs));
              s.Should().Contain(">");
              s.Should().Contain("WAN2");
              var regEx = new Regex(Pattern);
              regEx.IsMatch(s).Should().Be(true);
              MatchCollection matches = regEx.Matches(s);
              matches.Count.Should().Be(1);
              matches[0].Captures.Count.Should().Be(1);
              matches[0].Groups.Count.Should().Be(5);
              matches[0].Groups[0].Value.Should().Be(
                "WAN2 total TX: 6.3 GB ,RX: 6.9 GB");
              matches[0].Groups[1].Value.Should().Be("6.3");
              matches[0].Groups[2].Value.Should().Be("GB");
              matches[0].Groups[3].Value.Should().Be("6.9");
              matches[0].Groups[4].Value.Should().Be("GB");
            }
          }
        }
      }
    }

Visual Basic

    Private Async Function RunRemoteScript(
      commandLine As String) As Task(Of Boolean)
        Using telnet = New Client(
          "HostName",
          23,
          _cancellationSource.Token)
            If Not telnet.IsConnected Then Return False
            Dim loggedOn = Await telnet.TryLoginAsync(
              "username",
              "password",
              SocketTimeout, "#"))
            If Not loggedOn Then Return False
            Await telnet.WriteLine(commandLine)
            Dim serverResponse = Await telnet.TerminatedReadAsync(
              "#",
              TimeSpan.FromMilliseconds(SocketTimeout))
            Debug.Print(serverResponse)
            Await telnet.WriteLine("exit")
            Dim logoutMessage = Await telnet.ReadAsync(
              New TimeSpan(100))
            Debug.Print(logoutMessage)
        End Using
        Return True  ' If we got this far; celebrate
    End Function
Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 is compatible.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 is compatible.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 is compatible. 
.NET Framework net461 was computed.  net462 is compatible.  net463 was computed.  net47 was computed.  net471 was computed.  net472 is compatible.  net48 is compatible.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.
  • .NETFramework 4.6.2

    • No dependencies.
  • .NETFramework 4.7.2

    • No dependencies.
  • .NETFramework 4.8

    • No dependencies.
  • .NETStandard 2.0

    • No dependencies.
  • .NETStandard 2.1

    • No dependencies.
  • net6.0

    • No dependencies.
  • net8.0

    • No dependencies.

NuGet packages (4)

Showing the top 4 NuGet packages that depend on Telnet:

Package Downloads
TeamSpeak3.Metrics

Collect metrics from your TeamSpeak 3 Server

Rosystec.Scan.Lib

sensor aggregator

DreamNucleus.Heos

A .Net HEOS CLI client using Reactive Extensions

Simple.K.Socket

Package Description

GitHub repositories (1)

Showing the top 1 popular GitHub repositories that depend on Telnet:

Repository Stars
Kudayasu/Artifice
Xbox One Developer Mode Privilege Escalation
Version Downloads Last updated
0.13.0 12,096 7/8/2024
0.12.0 8,491 4/17/2024
0.11.3 156,282 9/17/2022
0.11.2 3,814 9/3/2022
0.11.1 1,511 9/2/2022
0.11.0 1,563 9/2/2022
0.10.2 2,822 8/22/2022
0.10.1 1,530 8/21/2022
0.10.0 1,218 8/20/2022
0.9.1 4,503 8/18/2022
0.9.0-beta0001 8,269 5/16/2018
0.8.6 264,923 9/3/2020
0.8.6-beta0001 409 9/2/2020
0.8.4 50,861 10/9/2019
0.8.3 25,321 3/7/2019
0.8.2 3,413 1/30/2019
0.8.1 134,240 5/8/2018
0.8.0 30,387 3/12/2017
0.7.0 10,751 9/6/2016
0.6.1 53,290 2/25/2016
0.6.0 1,567 1/27/2016
0.5.0 1,576 12/8/2015
0.4.0 3,695 10/27/2015
0.3.2 1,529 9/15/2015
0.3.1 2,461 6/20/2015
0.2.5 81,741 12/15/2014
0.2.0 1,322 11/27/2014
0.1.0 1,611 11/26/2014

0.13 extends the Client with a static flag SkipProactiveOptionNegotiation due to https://github.com/9swampy/Telnet/issues/79.