Against information leakage via electromagnetic emanation, electromagnetic absorption tape and electromagnetic shielding tape are expected as countermeasures. In this paper, we adopt these methods for HUBs and LAN connectors to conduct experiments and evaluate their effectiveness in reducing the amount of information leakage. We estimate the risk using channel capacity from the perspective of electromagnetic security. As a result, we can observe decrease in power and frequency shift. However, we conclude that although the frequency shift is effective as an EMC countermeasure, it does not effectively reduce the risk of information leakage. We show that evaluation using channel capacity is suitable for information security, such as estimating the effectiveness of a combination of multiple countermeasures and specifying the numerical goals to be achieved.