d0x2a.EmbeddedSsh 1.1.0

EmbeddedSsh

A minimal, embeddable SSH-2 server library for .NET 10.0 following RFC 4251-4254.

Features

• Zero external dependencies - All cryptographic primitives implemented from scratch
• Pure managed code - No native libraries or P/Invoke
• RFC compliant - Implements SSH-2 protocol (RFC 4251-4254)
• Modern cryptography:
  • ChaCha20-Poly1305 and AES-256-GCM ciphers
  • Curve25519 key exchange
  • Ed25519 host keys
  • RSA and Ed25519 public key authentication

Supported Algorithms

Installation

dotnet add package d0x2a.EmbeddedSsh

Quick Start

using System.Net;
using d0x2a.EmbeddedSsh;
using d0x2a.EmbeddedSsh.Auth;
using d0x2a.EmbeddedSsh.HostKeys;

// Generate or load host key
var hostKey = Ed25519HostKey.Generate();

// Configure server
var options = new SshServerOptions
{
    ServerVersion = "SSH-2.0-MyServer",
    Authenticator = new PasswordAuthenticator(new Dictionary<string, string>
    {
        ["user"] = "password"
    })
};
options.HostKeys.Add(hostKey);

// Start server
await using var server = new SshServer(options, new IPEndPoint(IPAddress.Any, 2222));

server.ConnectionAccepted += connection =>
{
    _ = Task.Run(async () =>
    {
        var channel = await connection.AcceptChannelAsync();
        // Handle channel...
    });
    return Task.CompletedTask;
};

server.Start();
await Task.Delay(Timeout.Infinite);

Public Key Authentication

Use AuthorizedKeysAuthenticator for SSH key authentication:

// From authorized_keys file
var content = File.ReadAllText("~/.ssh/authorized_keys");
var keys = AuthorizedKeysAuthenticator.ParseAuthorizedKeysFile(content);

var options = new SshServerOptions
{
    Authenticator = new AuthorizedKeysAuthenticator(
        new Dictionary<string, IEnumerable<AuthorizedKey>>
        {
            ["username"] = keys
        })
};

Building

# Build
dotnet build

# Run tests
dotnet test

# Create NuGet package
dotnet pack -c Release

# Run example server
cd samples/EmbeddedSsh.Example
dotnet run

Architecture

The library follows the SSH RFC layered architecture:

+-----------------------------------------+
|             SshServer                   |  Server integration
+-----------------------------------------+
|           Connection Layer              |  Channels, requests
+-----------------------------------------+
|             Auth Layer                  |  Authentication
+-----------------------------------------+
|           Transport Layer               |  Encryption, framing
+-----------------------------------------+
|            Protocol Layer               |  Message serialization
+-----------------------------------------+
|             Crypto Layer                |  Primitives
+-----------------------------------------+

Requirements

• .NET 10.0

License

MIT