Sustaining session connections

In an embodiment, techniques for sustaining session connections are provided. The techniques send heartbeat messages when not sending a message may cause the session connection to close because of a timeout condition. Heartbeat messages are valid transport layer messages that will be ignored by protocols at higher levels of a data communications stack. As an example, the techniques may send a TCP message containing only a carriage return and line feed ("CRLF") in its payload. Because the TCP layer considers a message containing only a CRLF to be a valid TCP message, intermediary computing devices such as proxy servers may not interpret heartbeat messages as "keep alive" messages, and may sustain session connections.