For use in a computer network facilitating communication sessions between network devices, a method of controlling the communication sessions, the method comprising the steps of:
- (a) providing network information;
- (b) providing access information;
- (c) passively listening to a portion of at least one of the communication sessions;
- (d) comparing said portion with said access information;
- and
- (e) when said at least one communication session is not allowed according to said access information, issuing a message to at least one of the network devices involved in said at least one session to stop further communication between the network devices.