F1 Application Protocol (F1AP) provides the signalling service between a gNB-CU and a gNB-DU of a gNB within an NG-RAN, or between a gNB-CU and a gNB-DU of an en-gNB within an E-UTRAN. The services provided by the F1AP are divided to UE-associated and non UE-associated. The UE-associated services are related to one UE and the non UE-associated services are related to the F1 interface. The F1AP is transfered over SCTP. The F1AP protocol is defined in TS 38.473. The F1AP Client Suite has been designed to act as a malicious gNB-CU that sends exceptional messages to the tested entity which is gNB-DU.