The Transport Layer facilitates the transparent data movement between end-users while offering dependable data transfer services to the layers above. The same layer uses flow control, segmentation and desegmentation, and error control, ensuring the reliability of a specific link. The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) belong to Layer 4 protocols.
Attacks at Layers 3 and 4 are typically categorized as infrastructure layer attacks. These attacks are often high-volume and try to overburden the network or application servers. However, infrastructure layer attacks have distinct signatures, making detection of such attacks easier.