Yes, by tampering with the firmware of network devices, packet hijacking and tampering can be achieved. The firmware of network devices (such as routers, switches, etc.) is the software that controls the behavior of the device. If an attacker can gain access to the device firmware and modify it, they may be able to perform the following attacks: 1. **Packet hijacking**: The attacker can capture and forward or modify the data packets passing through the device. This can be used for man-in-the-middle attacks (MITM), steal sensitive information or tamper with the content of the communication. 2. **Packet tampering**: The content of the data packet can be modified during transmission, which may cause data integrity to be compromised and the information received by both parties to be changed. 3. **Traffic redirection**: By modifying the routing information, the attacker can redirect the traffic to a server under their control for further monitoring and manipulation. 4. **Backdoor access**: Tampering with the firmware can create a backdoor that allows the attacker to access the network device at any time without being detected. For security reasons, network device firmware should be updated in a timely manner and obtained from trusted sources to reduce the risk of such attacks. In addition, enabling appropriate security features and monitoring devices can also help prevent potential attacks.