FxSsh

FxSsh is a lightweight SSH server side library.

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Nuget

PM> Install-Package FxSsh

Target netstandard2.1

RFCs

FxSsh adheres to the following RFC documents

• RFC4250 Protocol Assigned Numbers
• RFC4251 Protocol Architecture
• RFC4252 Authentication Protocol
• RFC4253 Transport Layer Protocol
• RFC4254 Connection Protocol
• RFC6668 SHA-2 Data Integrity Algorithms
• RFC8332 Use of RSA Keys with SHA-2

Sample code

static int windowWidth, windowHeight;

static void Main(string[] args)
{
    var rsa2048BitKey = "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";

    var server = new SshServer();
    server.AddHostKey("rsa-sha2-256", rsa2048BitKey);
    server.AddHostKey("rsa-sha2-512", rsa2048BitKey);
    server.ConnectionAccepted += server_ConnectionAccepted;

    server.Start();

    Task.Delay(-1).Wait();
}

static void server_ConnectionAccepted(object sender, Session e)
{
    Console.WriteLine("Accepted a client.");

    e.ServiceRegistered += e_ServiceRegistered;
    e.KeysExchanged += e_KeysExchanged;
}

private static void e_KeysExchanged(object sender, KeyExchangeArgs e)
{
    foreach (var keyExchangeAlg in e.KeyExchangeAlgorithms)
    {
        Console.WriteLine("Key exchange algorithm: {0}", keyExchangeAlg);
    }
}

static void e_ServiceRegistered(object sender, SshService e)
{
    var session = (Session)sender;
    Console.WriteLine("Session {0} requesting {1}.",
        BitConverter.ToString(session.SessionId).Replace("-", ""), e.GetType().Name);

    if (e is UserauthService)
    {
        var service = (UserauthService)e;
        service.Userauth += service_Userauth;
    }
    else if (e is ConnectionService)
    {
        var service = (ConnectionService)e;
        service.CommandOpened += service_CommandOpened;
        service.EnvReceived += service_EnvReceived;
        service.PtyReceived += service_PtyReceived;
        service.TcpForwardRequest += service_TcpForwardRequest;
        service.WindowChange += Service_WindowChange;
    }
}

static void Service_WindowChange(object sender, WindowChangeArgs e)
{
    // DEMO MiniTerm not support change window size
}

static void service_TcpForwardRequest(object sender, TcpRequestArgs e)
{
    Console.WriteLine("Received a request to forward data to {0}:{1}", e.Host, e.Port);

    var allow = true;  // func(e.Host, e.Port, e.AttachedUserauthArgs);

    if (!allow)
        return;

    var tcp = new TcpForwardService(e.Host, e.Port, e.OriginatorIP, e.OriginatorPort);
    e.Channel.DataReceived += (ss, ee) => tcp.OnData(ee);
    e.Channel.CloseReceived += (ss, ee) => tcp.OnClose();
    tcp.DataReceived += (ss, ee) => e.Channel.SendData(ee);
    tcp.CloseReceived += (ss, ee) => e.Channel.SendClose();
    tcp.Start();
}

static void service_PtyReceived(object sender, PtyArgs e)
{
    Console.WriteLine("Request to create a PTY received for terminal type {0}", e.Terminal);
    windowWidth = (int)e.WidthChars;
    windowHeight = (int)e.HeightRows;
}

static void service_EnvReceived(object sender, EnvironmentArgs e)
{
    Console.WriteLine("Received environment variable {0}:{1}", e.Name, e.Value);
}

static void service_Userauth(object sender, UserauthArgs e)
{
    Console.WriteLine("Client {0} fingerprint: {1}.", e.KeyAlgorithm, e.Fingerprint);

    e.Result = true;
}

static void service_CommandOpened(object sender, CommandRequestedArgs e)
{
    Console.WriteLine($"Channel {e.Channel.ServerChannelId} runs {e.ShellType}: \"{e.CommandText}\".");

    var allow = true;  // func(e.ShellType, e.CommandText, e.AttachedUserauthArgs);

    if (!allow)
        return;

    if (e.ShellType == "shell")
    {
        // requirements: Windows 10 RedStone 5, 1809
        // also, you can call powershell.exe
        var terminal = new Terminal("cmd.exe", windowWidth, windowHeight);

        e.Channel.DataReceived += (ss, ee) => terminal.OnInput(ee);
        e.Channel.CloseReceived += (ss, ee) => terminal.OnClose();
        terminal.DataReceived += (ss, ee) => e.Channel.SendData(ee);
        terminal.CloseReceived += (ss, ee) => e.Channel.SendClose(ee);

        terminal.Run();
    }
    else if (e.ShellType == "exec")
    {
        var parser = new Regex(@"(?<cmd>git-receive-pack|git-upload-pack|git-upload-archive) \'/?(?<proj>.+)\.git\'");
        var match = parser.Match(e.CommandText);
        var command = match.Groups["cmd"].Value;
        var project = match.Groups["proj"].Value;

        var git = new GitService(command, project);

        e.Channel.DataReceived += (ss, ee) => git.OnData(ee);
        e.Channel.CloseReceived += (ss, ee) => git.OnClose();
        git.DataReceived += (ss, ee) => e.Channel.SendData(ee);
        git.CloseReceived += (ss, ee) => e.Channel.SendClose(ee);

        git.Start();
    }
    else if (e.ShellType == "subsystem")
    {
        // do something more
    }
}

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License

The MIT license