The largest DDoS attacks recorded are un-amplified and un-spoofed. The sources are malware (see Mirai and its variants) via legitimate internet connections. Ev

The largest DDoS attacks recorded are un-amplified and un-spoofed. The sources are malware (see Mirai and its variants) via legitimate internet connections. Even the largest ISPs generally do not have enough spare capacity to just "block UDP packets," as the largest attacks are now measured in Tbps. There is also nothing stopping attackers from just sending TCP packets. As consumer internet speeds grow, DDoS grows.