VuGen's advanced Port mapping options let you configure the auto-detection options. VuGen's auto-detection analyzes the data that is sent to the server. It checks the data for a signature, a pattern in the data's content, that identifies the protocol. For the purpose of detecting a signature, all of the send buffers until the first receive buffer, are combined. All send buffers that were sent until a receive buffer is returned, are considered a single data transition. By default, no mappings are defined and VuGen employs auto-detection. In some protocols, VuGen determines the type in a single transition, (such as HTTP). Other network protocols require several transitions before determining the type. For this purpose, VuGen creates a temporary buffer for each server-port combination. If VuGen cannot determine the protocol type by reading the first transition buffers, it stores the data in a temporary buffer. It continues to read the incoming buffers until it detects a signature of a specific protocol.
By default, VuGen allows 4 transitions and uses a temporary buffer of 2048 bytes in order to detect a protocol signature. If VuGen has not yet determined the type after reaching the maximum number of transitions, or after reaching the maximum buffer size, it assigns the data to the Winsock protocol. If you did not instruct VuGen to record the Winsock protocol (in the multi-protocol selection), VuGen discards the data.
You can change the maximum number of buffers you want VuGen to read in order to detect the protocol type. You can also specify the size of the temporary buffer. In instances where the amount of data in the first send buffers, is greater than the size of the temporary buffer, VuGen cannot auto-detect the protocol type. In this case, you should increase the size of the temporary buffer.
When working with the above network level protocols, we recommend that you allow VuGen to use auto-detection to determine the protocol type. In most cases, VuGen's recorder is able to recognize the signatures of these protocols. It then automatically processes them according to the protocol specifications. In certain instances, however, VuGen may be unable to recognize the protocol. For example:
The protocol signature closely resembles an existing protocol, resulting in erroneous processing.
There is no unique signature for the protocol.
The protocol uses SSL encryption, and therefore cannot be recognized on a Winsock level.
In all of the above cases, you can supply information to uniquely identify the server and port hosting the protocol.