EXCSAT packet
The EXCSAT (Exchange Server Attribute) packet is sent by the client as part of the authentication process, typically as the very packet. It contains information about the client.
Properties
SRVNAM (string): the name of the client machine initiating the connection. Can be an IP address or a host name.
EXTNAM (object): an object describing various aspects of the connection, with the properties:
clientName (string): the name of the client application
clientProductId (string): an ID for the product, e.g. JCC04260300
userId (string): the OS name of the user connecting to the server
SRVRLSLV (string): the release level of the client, e.g. SQL11054 for a JDBC client
SRVCLSNM (string): the server class of the client, e.g. QDB2/NT64 for a Windows client
This packet type often contains other properties, but they are usually not relevant, except for advanced cases.
Example
You could change the OS name of the user with
context.packet.EXTNAM.userId = 'Anonymous';