A communication control apparatus, comprising: a receiver configured to receive, from a first node, data including first identification information or second identification information, the first identification information identifying data addressed to a second node which does not execute a process for detecting a replay attack and which does not receive a frame including an authentication code, the second identification information identifying data which is not received by the second node, the first node and the second node being connected to a Controller Area Network, CAN; and a controller configured to generate a first authentication code by using first data, when the receiver has received the first data including the first identification information, wherein the receiver receives, from the first node, second data including the second identification information and a second authentication code that the first node has generated by using the first data, and the controller decides whether to make the second node abort a process of the data reported using the first identification information, on the basis of a result of a comparison between the first authentication code and the second authentication code, the comparison is executed to verify whether the replay attack has occurred; wherein the first authentication codes are generated by using the first data and a first counter value of a first counter in the communication control apparatus and the second authentication codes are generated by using the first data and a second counter value of a second counter in the first node, wherein a common initial value is given to the first counter and the second counter and said counter values are respectively different for each frame. a receiver configured to receive, from a first node, data including first identification information or second identification information, the first identification information identifying data addressed to a second node which does not execute a process for detecting a replay attack and which does not receive a frame including an authentication code, the second identification information identifying data which is not received by the second node, the first node and the second node being connected to a Controller Area Network, CAN; and a controller configured to generate a first authentication code by using first data, when the receiver has received the first data including the first identification information, wherein the receiver receives, from the first node, second data including the second identification information and a second authentication code that the first node has generated by using the first data, and the controller decides whether to make the second node abort a process of the data reported using the first identification information, on the basis of a result of a comparison between the first authentication code and the second authentication code, the comparison is executed to verify whether the replay attack has occurred; wherein the first authentication codes are generated by using the first data and a first counter value of a first counter in the communication control apparatus and the second authentication codes are generated by using the first data and a second counter value of a second counter in the first node, wherein a common initial value is given to the first counter and the second counter and said counter values are respectively different for each frame.