Delphi DLL

SSH Through a SOCKS Proxy

Demonstrates connecting to an SSH server through a SOCKS4 or SOCKS5 proxy. Set the SOCKS properties before calling Connect, and set SocksVersion to match the proxy server.

Background: SOCKS is a general-purpose TCP relay, so unlike an HTTP proxy it is designed from the start to carry arbitrary protocols — usually the smoother option for SSH. The version matters: SOCKS4 supports only a username with no password, while SOCKS5 supports full login/password authentication as well as IPv6 and remote DNS resolution. Note this is the inverse of dynamic port forwarding: here a SOCKS proxy is used to reach the SSH server, rather than SSH providing a SOCKS proxy.

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Delphi DLL

var
success: Boolean;
ssh: HCkSsh;
hostname: PWideChar;
port: Integer;
password: PWideChar;

begin
success := False;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  Demonstrates connecting to an SSH server through a SOCKS4 or SOCKS5 proxy.

ssh := CkSsh_Create();

//  Set the SOCKS proxy properties before connecting.  The hostname may be a domain name or an
//  IP address.
CkSsh_putSocksHostname(ssh,'socks.example.com');
CkSsh_putSocksPort(ssh,1080);
CkSsh_putSocksUsername(ssh,'mySocksLogin');
CkSsh_putSocksPassword(ssh,'mySocksPassword');

//  Set the version to match the proxy server: 4 or 5.
//  Note: SOCKS4 supports only a username, with no password.  SOCKS5 supports full
//  login/password authentication.
CkSsh_putSocksVersion(ssh,5);

hostname := 'ssh.example.com';
port := 22;
success := CkSsh_Connect(ssh,hostname,port);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

Memo1.Lines.Add('Connected to the SSH server through the SOCKS proxy.');

//  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 := CkSsh_AuthenticatePw(ssh,'mySshLogin',password);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

//  ... use the SSH connection normally ...

CkSsh_Disconnect(ssh);

CkSsh_Dispose(ssh);