Delphi ActiveX

SSH Tunnel Through an Outbound SOCKS Proxy

Demonstrates reaching the SSH server through an outbound SOCKS proxy using the SocksVersion, SocksHostname, SocksPort, SocksUsername, and SocksPassword properties.

Background: This is the reverse direction from dynamic forwarding: here a SOCKS proxy is used to reach the SSH server, for networks where outbound connections must pass through one. SocksVersion is the switch — 0 means no SOCKS, while 4 or 5 selects the protocol. SOCKS5 supports username/password authentication and remote DNS; SOCKS4 supports only a username.

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var
success: Integer;
tunnel: TChilkatSshTunnel;
sshPort: Integer;
password: WideString;
listenPort: Integer;
waitForThreadExit: Integer;

begin
success := 0;

//  Demonstrates reaching the SSH server through an outbound SOCKS proxy using the SshTunnel
//  properties SocksVersion, SocksHostname, SocksPort, SocksUsername, and SocksPassword.

tunnel := TChilkatSshTunnel.Create(Self);

//  Set SocksVersion to 4 or 5 to route the outbound connection to the SSH server through a SOCKS
//  proxy.  A value of 0 (the default) means no SOCKS proxy.
tunnel.SocksVersion := 5;
tunnel.SocksHostname := 'socks.example.com';
tunnel.SocksPort := 1080;

//  SOCKS4 supports only a username; SOCKS5 supports username and password.
tunnel.SocksUsername := 'myProxyLogin';
tunnel.SocksPassword := 'myProxyPassword';

tunnel.DestHostname := 'db.internal.example.com';
tunnel.DestPort := 5432;

//  Connect to the SSH server through the SOCKS proxy configured above.
sshPort := 22;
success := tunnel.Connect('ssh.example.com',sshPort);
if (success = 0) then
  begin
    Memo1.Lines.Add(tunnel.LastErrorText);
    Exit;
  end;

//  Normally you would not hard-code the password in source.  You should instead obtain it
//  from an interactive prompt, environment variable, or a secrets vault.
password := 'mySshPassword';

success := tunnel.AuthenticatePw('mySshLogin',password);
if (success = 0) then
  begin
    Memo1.Lines.Add(tunnel.LastErrorText);
    Exit;
  end;

listenPort := 1080;
success := tunnel.BeginAccepting(listenPort);
if (success = 0) then
  begin
    Memo1.Lines.Add(tunnel.LastErrorText);
    Exit;
  end;
Memo1.Lines.Add('Tunnel established through the SOCKS proxy.');

waitForThreadExit := 1;
success := tunnel.CloseTunnel(waitForThreadExit);
if (success = 0) then
  begin
    Memo1.Lines.Add(tunnel.LastErrorText);
    Exit;
  end;