The SocketTools .NET Edition supports the ability to create secure connections using the Transport Layer Security (TLS) protocol. In most cases, it is as simple as setting the Secure property to true or specifying an additional option when the Connect method is called. In some cases, certain Internet application protocols have additional requirements in terms of how the secure connection is established . Secure connections may either be implicit or explicit, depending on the protocol. An implicit secure connection is one where the client and server begin negotiating the security options as soon as the connection is established. In most cases, a server which accepts secure implicit connections listens on a port number that is different from the default port it uses for standard, non-secure connections. An example of this is the Hypertext Transfer Protocol (HTTP) which accepts standard connections on port 80 and secure connections on port 443. When a client connects to port 443, the server automatically assumes that the client wants a secure connection.

On the other hand, an explicit connection requires that the client explicitly specify to the server that it wants a secure connection. Typically this is done by the client sending a command to the server that causes the server to begin negotiating with the client to establish a secure session. An example of this is the File Transfer Protocol (FTP), where the client can use the AUTH command to tell the server that it wants a secure connection. Servers may also support both explicit and implicit secure connections, based on which port the client connects to. SocketTools supports both implicit and explicit secure connections. If the Secure property is set to true prior to calling the Connect method, then an implicit secure connection is established. Setting the Secure property to true after a connection has been established will cause SocketTools to begin negotiating a secure connection at that time.

In addition to establishing a secure connection, you may also be required to provide additional authentication information to the server in form a client certificate. For example, a server may require that the client provide a certificate in addition to or instead of a username and password. To support this, your application must specify the security credentials for the client prior to establishing a connection. For more information, refer to the CertificateStore and CertificateName properties in the Technical Reference.