TLSServer Component

Properties Methods Events Configuration Settings Errors

The TLSServer component implements server-side functionality of the TLS protocol. In the TLS-disabled mode it works as a plain TCP server.

Syntax

TsbxTLSServer

Remarks

Use this component to accept TLS-encrypted or plain TCP connections in your application.

Follow the below steps to set up and run the server in your code:

Create an instance of the server component and set up the license, if assumed by the edition you are using:
view source
var server = new Tlsserver();
server.RuntimeLicense = "5342..0000";
Set up the listening port (make sure it is not in use):
view source
server.Port = 3456;
Tell the component whether TLS connections should be enforced:
view source
server.UseTLS = false; // set to true to enable TLS
(TLS-enabled servers only) Configure TLS parameters. The exact way of doing that may vary for different scenarios and security requirements. At the very least you need to set up the certificate chain that the server will use to authenticate itself to connecting clients. If you don't, the component will generate a dummy certificate itself, however, that certificate is unlikely to pass any security requirements. It will let you accept test connections though.
Below is an example of tuning up the TLS parameters of the server:
view source
// *** Switching TLS on and enabling the implicit mode ***

server.UseTLS = true;
server.TLSSettings.TLSMode = smImplicitTLS;

// Loading the certificate chain
var mgr = new Certificatemanager();
mgr.RuntimeLicense = "5342..0000";

// *** Setting up the host certificate ***

// - it should be issued in the name that matches the hostname (such as domain.com) or its IP address (1.2.3.4),
// - it must have an associated private key - so likely is provided in PFX or PEM format.
mgr.ImportFromFile("CertTLSServer.pfx", "password");
server.ServerCertificates.Add(mgr.Certificate);

// The CA certificate: this is to help connecting clients validate the chain.
mgr.ImportFromFile("CertCA.cer", "");
server.ServerCertificates.Add(mgr.Certificate);

// *** Adjusting finer-grained TLS settings ***

// - session resumption (allows for faster handshakes for connections from the same origin)
server.TLSSettings.UseSessionResumption = true;

// - secure configuration
server.TLSSettings.BaseConfiguration = stpcHighlySecure;

// - disabling a ciphersuite we dislike (just because we can):
server.TLSSettings.Ciphersuites = "-DHE_RSA_AES128_SHA"

// *** Configuring versions ***

// The default version setting at the time of writing (May 2021) is TLS 1.2 and TLS 1.3,
// but that may change in future versions. The following tune-up additionally activates TLS 1.1 and TLS 1.0,
// which weakens security, but may be necessary to accept connections from older clients:
server.TLSSettings.Versions = csbTLS1 | csbTLS11 | csbTLS12 | csbTLS13;
Now that your server has been fully set up, activate it:
view source
server.Start();
Once the Start call completes, your server can accept connections from clients. Each accepted connection runs in a separate thread, not interfering with each other or your own threads. The server communicates its ongoing activities to your application by throwing events:
- Accept to notify you about a new incoming connection. This event lets you accept or reject it.
- Connect to notify your code of an accepted connection. This event introduces a ConnectionID, a unique identifier that you can use to track the connection throughout its lifetime.
- Disconnect to notify you that a connection has been closed.
- TLSEstablished and TLSShutdown to let you know that a TLS layer has been activated/deactivated.
- Data to notify you about a piece of data received from the remote side.
- Error to report a protocol or other error.
- CertificateValidate to communicate the client authentication event to your code. To access the certificate(s) provided by the authenticating client, pin the client and use the PinnedClientChain property to access its chain:
  view source
  server.PinClient(e.ConnectionID);
  e.Accept = CheckCert(server.PinnedClientChain);
Note: every such event is thrown from the respective connection thread, so make sure you use some synchronization mechanism when dispatching the events to your UI thread - for example, by updating UI controls by sending a Window Message rather than accessing the controls directly.

Use SendData and SendText to send data back to a client. When sending data, provide the ConnectionID that is associated with that client. Call DropClient to terminate a client connection.
To stop the server, call Stop:
view source
server.Stop();

TLSServer and SSLLabs

Qualys SSLLabs (https://www.ssllabs.com/) has been long known as a comprehensive TLS site quality checking tool. It is now a de-facto standard and a sign of good taste to aspire for the best SSLLabs test result for your web presence. SecureBlackbox developers share that effort and want to help their customers build secure TLS endpoints that can be independently endorsed by third-party evaluators like SSLLabs.

Having said that, when assessing SecureBlackbox TLS-capable servers that are configured to use their default setup, you will often end up with a lower SSLLabs score than you could have. There is a simple reason for that. Being a vendor of a library used by thousands of customers, we have to find a delicate balance between security, compatibility, and keeping class contracts rolling from one product build to another. This makes the default configuration of the components not the strongest possible. To put it simple, we could easily make the default component setup bulletproof - but having done that, we would have likely ended up with hundreds of customers stuck with legacy environments (and there are a lot of them around) losing their connectivity.

If you are looking at achieving the best score at SSLLabs, please read on. The below guidance aims to help you tune up the server component in the way that should give you an A score.

First, switch your server to the highly secure base configuration:

server.TLSSettings.BaseConfiguration = stpcHighlySecure;

This should immediately give you an A, or a T if your server certificate does not chain up to a trusted anchor.

Some warnings will still be included in the report. One of those is related to the session resumption. It is normally shown in orange:

Session resumption (caching): No (IDs assigned but not accepted)

This literally means that the server is not configured to re-use older sessions, which may put extra computational burden on clients and itself. Use the following setting to enable session caching:

server.TLSSettings.UseSessionResumption = true;

Besides, the report may show that there are some weak ciphersuites. All of those should be shown in orange (there should not be any reds; if there are - please let us know), which means they are only relatively weak. While switching them off may affect the interoperability level of the server, you may still want to do that. By using the below approach you can disable individual ciphersuites selectively. For example, if the report shows that TLS_DHE_RSA_WITH_AES128_CBC_SHA256 and TLS_DHE_RSA_WITH_AES256_CBC_SHA256 are weak (because of their CBC mode), you can disable them in the following way:

server.TLSSettings.Ciphersuites = '-DHE_RSA_AES128_SHA256;-DHE_RSA_AES256_SHA256';

Note that SBB uses slightly different, simpler naming convention by dropping unnecessart WITH and CBC. Let us know if you have difficulties matching the ciphersuite names.

Property List

The following is the full list of the properties of the component with short descriptions. Click on the links for further details.


Active	Indicates whether the server is active and is listening to new connections.
BoundPort	Indicates the bound listening port.
ErrorOrigin	Indicates the endpoint where the error originates from.
ErrorSeverity	The severity of the error that happened.
ExternalCrypto	Provides access to external signing and DC parameters.
HandshakeTimeout	Specifies the handshake timeout in milliseconds.
Host	The host to bind the listening port to.
PinnedClient	Populates the pinned client details.
PinnedClientChain	Contains the certificate chain of the pinned client.
Port	Specifies the port number to listen for connections on.
PortRangeFrom	Specifies the lower limit of the listening port range for incoming connections.
PortRangeTo	Specifies the upper limit of the listening port range for incoming connections.
ServerCertificates	The server's TLS certificates.
SessionTimeout	Specifies the default session timeout value in milliseconds.
SocketSettings	Manages network connection settings.
TLSSettings	Manages TLS layer settings.
UseTLS	Enables or disables the TLS requirement.
WebsiteName	Specifies the web site name to use in the certificate.

Method List

The following is the full list of the methods of the component with short descriptions. Click on the links for further details.


Config	Sets or retrieves a configuration setting.
DropClient	Terminates a client connection.
ListClients	Enumerates the connected clients.
PinClient	Takes a snapshot of the connection's properties.
SendData	Sends a data buffer to a connection client.
SendKeepAlive	Sends a keep-alive packet.
SendText	Sends a text string to a client.
Start	Starts the TLS server.
Stop	Stops the TLS server.

Event List

The following is the full list of the events fired by the component with short descriptions. Click on the links for further details.


Accept	Reports an incoming connection.
CertificateValidate	Fires when a client certificate needs to be validated.
Connect	Reports an accepted connection.
Data	Supplies a data chunk received from a client.
Disconnect	Fires to report a disconnected client.
Error	Information about errors during data delivery.
ExternalSign	Handles remote or external signing initiated by the server protocol.
Notification	This event notifies the application about an underlying control flow event.
TLSEstablished	Reports the setup of a TLS session.
TLSPSK	Requests a pre-shared key for TLS-PSK.
TLSShutdown	Reports closure of a TLS session.

Configuration Settings

The following is a list of configuration settings for the component with short descriptions. Click on the links for further details.


ClientAuth	Enables or disables certificate-based client authentication.
DualStack	Allows the use of ip4 and ip6 simultaneously.
Host	The host to bind to.
ServerSSLDHKeyLength	Sets the size of the TLS DHE key exchange group.
TLSExtensions	Provides access to TLS extensions.
WebsiteName	The website name for the TLS certificate.
CheckKeyIntegrityBeforeUse	Enables or disable private key integrity check before use.
CookieCaching	Specifies whether a cookie cache should be used for HTTP(S) transports.
Cookies	Gets or sets local cookies for the component (supported for HTTPClient, RESTClient and SOAPClient only).
DefDeriveKeyIterations	Specifies the default key derivation algorithm iteration count.
EnableClientSideSSLFFDHE	Enables or disables finite field DHE key exchange support in TLS clients.
GlobalCookies	Gets or sets global cookies for all the HTTP transports.
HttpUserAgent	Specifies the user agent name to be used by all HTTP clients.
LogDestination	Specifies the debug log destination.
LogDetails	Specifies the debug log details to dump.
LogFile	Specifies the debug log filename.
LogFilters	Specifies the debug log filters.
LogFlushMode	Specifies the log flush mode.
LogLevel	Specifies the debug log level.
LogMaxEventCount	Specifies the maximum number of events to cache before further action is taken.
LogRotationMode	Specifies the log rotation mode.
MaxASN1BufferLength	Specifies the maximal allowed length for ASN.1 primitive tag data.
MaxASN1TreeDepth	Specifies the maximal depth for processed ASN.1 trees.
OCSPHashAlgorithm	Specifies the hash algorithm to be used to identify certificates in OCSP requests.
UseOwnDNSResolver	Specifies whether the client components should use own DNS resolver.
UseSharedSystemStorages	Specifies whether the validation engine should use a global per-process copy of the system certificate stores.
UseSystemOAEPAndPSS	Enforces or disables the use of system-driven RSA OAEP and PSS computations.
UseSystemRandom	Enables or disables the use of the OS PRNG.

SecureBlackbox 2020 Delphi Edition