使用 C# 建立 MySQL 连接的 SSH 隧道

Posted 2023-03-23

【中文标题】使用 C# 建立 MySQL 连接的 SSH 隧道

【英文标题】：SSH tunneling a MySQL connection using C#

【发布时间】：2015-12-21 12:47:26

【问题描述】：

我试图使用 SSH 隧道通过 C# 访问我的 mysql 数据库，但我遇到了异常

无法连接到任何指定的 MySQL 主机。

我在这个帮助下得到了这个代码：C# SSH tunnel to MySQL server

这是我的代码：

PasswordConnectionInfo connectionInfo = new PasswordConnectionInfo("example.com", 2222, "username", "password");
connectionInfo.Timeout = TimeSpan.FromSeconds(30);

using (var client = new SshClient(connectionInfo))

    try
    
        Console.WriteLine("Trying SSH connection...");
        client.Connect();
        if (client.IsConnected)
        
            Console.WriteLine("SSH connection is active: 0", client.ConnectionInfo.ToString());
        
        else
        
            Console.WriteLine("SSH connection has failed: 0", client.ConnectionInfo.ToString());
        

        Console.WriteLine("\r\nTrying port forwarding...");
        var portFwld = new ForwardedPortLocal(IPAddress.Loopback.ToString(),2222, "example.com", 3306); 
        client.AddForwardedPort(portFwld);
        portFwld.Start();
        if (portFwld.IsStarted)
        
            Console.WriteLine("Port forwarded: 0", portFwld.ToString());
    Console.WriteLine("\r\nTrying database connection...");

 DBConnect dbConnect = new DBConnect("127.0.0.1", "database", "username", "password", "3306");
    int id =  dbConnect.Count("table");
    MessageBox.Show(id + " count ");
            
            else
            
                Console.WriteLine("Port forwarding has failed.");
            

        
        catch (SshException ex)
        
            Console.WriteLine("SSH client connection error: 0", ex.Message);
        
        catch (System.Net.Sockets.SocketException ex1)
    
        Console.WriteLine("Socket connection error: 0", ex1.Message);
    

private MySqlConnection connection;

private string server;
public string Server

    get
    
        return this.server;
    
    set
    
        this.server = value;
    


private string database;
public string Database

    get
    
        return this.database;
    
    set
    
        this.database = value;
    


private string uid;
public string Uid

    get
    
        return this.server;
    
    set
    
        this.server = value;
    


private string password;
public string Password

    get
    
        return this.password;
    
    set
    
        this.password = value;
    


private string port;
public string Port

    get
    
        return this.port;
    
    set
    
        this.port = value;
    


//Constructor
public DBConnect(string server, string database, string uid, string password, string port = "3306")

    this.server = server;

    this.database = database;
    this.uid = uid;
    this.password = password;
    this.port = port;

    Initialize();


//Initialize values
private void Initialize()

    string connectionString;
    connectionString = "SERVER=" + server + ";" + "DATABASE=" + database + ";" + "UID=" + uid + ";" + "PASSWORD=" + password + ";";
    connection = new MySqlConnection(connectionString);



//open connection to database
private bool OpenConnection()

    try
    
        connection.Open();
        Console.WriteLine("MySQL connected.");
        return true;
    
    catch (MySqlException ex)
    
        //When handling errors, you can your application's response based on the error number.
        //The two most common error numbers when connecting are as follows:
        //0: Cannot connect to server.
        //1045: Invalid user name and/or password.
        switch (ex.Number)
        
            case 0:
                Console.WriteLine("Cannot connect to server.  Contact administrator");
                break;

            case 1045:
                Console.WriteLine("Invalid username/password, please try again");
                break;

            default:
                Console.WriteLine("Unhandled exception: 0.", ex.Message);
                break;

        
        return false;
    


//Close connection
private bool CloseConnection()

    try
    
        connection.Close();
        return true;
    
    catch (MySqlException ex)
    
        Console.WriteLine(ex.Message);
        return false;
    


//Count statement
public int Count(string tableName)

    string query = "SELECT Count(*) FROM " + tableName;
    int Count = -1;

    //Open Connection
    if (this.OpenConnection() == true)
    
        //Create Mysql Command
        MySqlCommand cmd = new MySqlCommand(query, connection);

        //ExecuteScalar will return one value
        Count = int.Parse(cmd.ExecuteScalar() + "");

        //close Connection
        this.CloseConnection();

        return Count;
    

    return Count;

我在控制台中得到的输出是：

Trying SSH connection...
A first chance exception of type 'System.ObjectDisposedException' occurred in mscorlib.dll
A first chance exception of type 'System.ObjectDisposedException' occurred in System.dll
SSH connection is active: Renci.SshNet.PasswordConnectionInfo

Trying port forwarding...
Port forwarded: Renci.SshNet.ForwardedPortLocal
A first chance exception of type 'Renci.SshNet.Common.SshConnectionException' occurred in Renci.SshNet.dll

Trying database connection...
A first chance exception of type 'System.Net.Sockets.SocketException' occurred in System.dll
A first chance exception of type 'System.Net.Sockets.SocketException' occurred in MySql.Data.dll
A first chance exception of type 'MySql.Data.MySqlClient.MySqlException' occurred in MySql.Data.dll
A first chance exception of type 'MySql.Data.MySqlClient.MySqlException' occurred in MySql.Data.dll
 Error: 0 : Unable to connect to any of the specified MySQL hosts.
A first chance exception of type 'MySql.Data.MySqlClient.MySqlException' occurred in MySql.Data.dll
A first chance exception of type 'MySql.Data.MySqlClient.MySqlException' occurred in MySql.Data.dll
Unhandled exception: Unable to connect to any of the specified MySQL hosts..

更新：

我已将端口转发设置更改为：

var portFwld = new ForwardedPortLocal("127.0.0.1", 1000, "127.0.0.1", 3306);

我已将 mySQL 字符串更改为：

connectionString = "server=127.0.0.1;port=1000; UID=username; password=password; database=data1; charset=utf8;Allow User Variables=True";

我正在连接到 ssh 并且我的端口被转发，但我仍然无法连接到 MySQL 数据库，我遇到了一个异常：

A first chance exception of type 'System.IO.EndOfStreamException' occurred in MySql.Data.dll
A first chance exception of type 'MySql.Data.MySqlClient.MySqlException' occurred in MySql.Data.dll
A first chance exception of type 'MySql.Data.MySqlClient.MySqlException' occurred in MySql.Data.dll
 Error: 0 : Reading from the stream has failed.

【参考方案1】：

您必须将 MySQL 连接到转发的绑定端口。 IE。到 2222。

或者在语义上更正确，使用portFwld.BoundPort。等效地，使用portFwld.BoundHost。

DBConnect dbConnect = new DBConnect(portFwld.BoundHost, "database", "username", "password", portFwld.BoundPort);

---

还请注意，将 MySQL 主机称为“localhost”而不是“example.com”更有意义，因为主机名是在服务器端解析的。在服务器端，您通常不会连接到“example.com”，而是连接到“localhost”。

var portFwld = new ForwardedPortLocal(IPAddress.Loopback.ToString(), 2222, "localhost", 3306); 

---

当然，您需要在需要隧道时保持 SSH 会话打开。所以你必须在using 块内连接到数据库：

using (var client = new SshClient(connectionInfo))

    ...
    client.Connect();
    ...
    portFwld.Start();
    ... 
    DBConnect dbConnect = new DBConnect(portFwld.BoundHost, "database", "username", "password", portFwld.BoundPort);