A security apparatus ES arranged to be positioned between at least a first domain having a first sensitivity level A and at least a second domain having a second sensitivity level B, bearing in mind that the security level A is different from the security level B, characterized in that it comprises at least the following elements: • a physical material layer H and a plurality of interfaces I allowing for the exchange of data between said security apparatus and the various domains A, B, a data flow being emitted from the first domain having a sensitivity level A, transits via the physical material layer H and via a virtualization layer V, then via an airlock block and eventually arrives at the second domain having a sensitivity level B, • the virtualization layer V is implemented on the physical layer H and positioned between said physical layer H and at least a set consisting of at least three compartmentalized blocks, BLA, BLB, MDS, said compartmentalized blocks resting on the physical layer H and the virtualization layer, said at least three compartmentalized blocks are not in the virtualization layer, and said blocks consisting of at least one of the elements taken from the following list: • a software block A, BLA, comprising the set of network functions allowing to process data of security level A, • a software block B, BLB, comprising the set of network functions allowing to process data of security level B, • a security module software block, MDS, or airlock positioned between at least one block of BLA type and at least one block of BLB type, said security module being designed to monitor the exchanges of data between said blocks BLA and BLB, said security module MDS comprising all the security, filtering or cryptographic function transformations. • a physical material layer H and a plurality of interfaces I allowing for the exchange of data between said security apparatus and the various domains A, B, a data flow being emitted from the first domain having a sensitivity level A, transits via the physical material layer H and via a virtualization layer V, then via an airlock block and eventually arrives at the second domain having a sensitivity level B, • the virtualization layer V is implemented on the physical layer H and positioned between said physical layer H and at least a set consisting of at least three compartmentalized blocks, BLA, BLB, MDS, said compartmentalized blocks resting on the physical layer H and the virtualization layer, said at least three compartmentalized blocks are not in the virtualization layer, and said blocks consisting of at least one of the elements taken from the following list: • a software block A, BLA, comprising the set of network functions allowing to process data of security level A, • a software block B, BLB, comprising the set of network functions allowing to process data of security level B, • a security module software block, MDS, or airlock positioned between at least one block of BLA type and at least one block of BLB type, said security module being designed to monitor the exchanges of data between said blocks BLA and BLB, said security module MDS comprising all the security, filtering or cryptographic function transformations. • a software block A, BLA, comprising the set of network functions allowing to process data of security level A, • a software block B, BLB, comprising the set of network functions allowing to process data of security level B, • a security module software block, MDS, or airlock positioned between at least one block of BLA type and at least one block of BLB type, said security module being designed to monitor the exchanges of data between said blocks BLA and BLB, said security module MDS comprising all the security, filtering or cryptographic function transformations. <EOS>