An on-path attack allows an attacker to intercept and read, modify, or redirect communication between two parties without their knowledge. This used to be known as a man-in-the-middle attack. The attacker 'sits' on the communication's path and can perform eavesdropping or active interception. ARP poisoning, however, is a technique that could be used to facilitate an on-path attack by corrupting the ARP cache and redirecting network traffic through the attacker's machine. A side-channel attack is a different kind of attack that involves gathering information from the physical implementation of a system. A replay attack involves intercepting and retransmitting a message, but it does not involve inserting the attacker into an ongoing communication channel.