5. Conclusion

As it stands, it seems that exploiting hidden channels on a network is not that simple. However, their detection requires complex mechanisms to be put in place, with the greatest difficulty coming from all that needs to be monitored simultaneously.

Is it possible to prevent covert channels? Although it may seem difficult, it is feasible... on certain systems. Theoretical security models, such as the Bell-La Padula model, propose guaranteeing data confidentiality. Confidentiality does not preclude the existence of covert channels, as we have seen with the SSH protocol. Other models, such as Biba, seek to guarantee data integrity. The realization of such systems, in the computer sense, is not without its problems, particularly in terms of performance. But these models enable us to build systems for which certain properties have been proven.

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