• data aggregation
• IPsec
• java
• location based system
• racoon
• sensors
• setkey
• sunxacml
• XACML

This thesis takes place within the trace-them project. It consists of two main parts. The first one is a library that provides facilities to take
policy-based decisions about data access. In trace-them, the data to be accessed are location information about resources being traced. The
policies describing whether or not grant access permissions are based on properties of the inquiring entity, of the required resource and action, and also on environment properties that may change (as presence of some type of emergency or time ranges in which a subject is allowed to ask for something or not).
In the second part, some scripts are provided to configure IPsec communication between Ubuntu-like systems using racoon and setkey open source tools. In trace-them some gprs sensors have to communicate with a sensor server. Due to the possibility for the IP address to change during
a gprs connection and to the impossibility to know what IP will be assigned to each sensor, an appropriate type of configuration is chosen for
sensors and sensor server.