Delphi ActiveX

SSH Tunnel Timeouts and IP Preference

Demonstrates the ConnectTimeoutMs, IdleTimeoutMs, and PreferIpv6 properties, which govern how long the tunnel waits to connect and to transfer data, and which IP version it prefers.

Background: ConnectTimeoutMs bounds how long a connection attempt blocks — important so an unreachable server fails promptly instead of hanging — while IdleTimeoutMs guards against a stalled transfer holding a connection open indefinitely. PreferIpv6 only matters when a hostname resolves to both address families, choosing which to try first; the default prefers IPv4.

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

begin
success := 0;

//  Demonstrates the SshTunnel connection-behavior properties ConnectTimeoutMs, IdleTimeoutMs, and
//  PreferIpv6.

tunnel := TChilkatSshTunnel.Create(Self);

//  Maximum time to establish the SSH connection (default 30000 ms).
tunnel.ConnectTimeoutMs := 10000;

//  Stall timeout for tunnel data-transfer operations (default 30000 ms).
tunnel.IdleTimeoutMs := 15000;

//  When a hostname resolves to both IPv4 and IPv6, prefer IPv6.  The default (0) prefers IPv4.
tunnel.PreferIpv6 := 1;

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

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.');

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