Mitigation Method	Operation Principle	Resource Usage on Server	Effectiveness on Attack Volume	Spoofing Protection	Latency Impact	Recommended Use Case	Pros	Cons
ACK Cookie	Sends two ACK packets: one valid, one invalid; verifies client response	Low (only ACK responses handled)	Medium to High	Good	Low	When reverse bandwidth is sufficient	Accurate spoof detection; simple mechanism	Requires reverse bandwidth; slightly more complex
SYN Cookie	Encodes connection info in SYN/ACK sequence number (cookie)	Very Low (stateless until ACK arrives)	High	Good	Low to medium	High-volume attacks without reverse bandwidth	Stateless; scalable under high load	Limited TCP options; some legitimate options lost
SYN Retransmission Verification	Drops initial SYN, waits for retransmitted SYNs to confirm legitimacy	Low to Medium	Low to Medium	Moderate	Medium (waits for retransmissions)	Low volume attacks or environments with retransmission	Simple; leverages TCP behavior	Not suitable for high volume; delay in connection setup
TCP SYN Cache	Stores hashed SYN info, allocates full connection only after ACK	Low to Medium	Medium to High	Good	Low	General purpose, moderate attack volume	Reduces memory use; allows full handshake later	Cache overflow risk; may drop connections under heavy load
TCP SYN Proxy	Completes handshake on behalf of server, forwards only verified connections	Low on server (proxy handles load)	High	Excellent	Medium (proxy delay)	High-volume attacks, critical servers	Strong spoof protection; protects server resources	Adds latency; complexity in setup; may break TCP options
TCP Window Scaling Verification	Validates window scaling option to filter invalid SYNs	Minimal	Low to Medium	Moderate	Negligible	Environments where spoofed packets misuse window scaling	Lightweight verification	Limited filtering power; may block some legit clients
Three-Way Handshake Completion Verification	Allocates resources only after full handshake	Low	Medium to High	Good	Low	Standard defense for most TCP servers	Prevents early resource exhaustion	May delay connection establishment slightly
TCP Timestamp Validation	Checks TCP timestamp option in SYN packets	Minimal	Low to Medium	Moderate	Negligible	Supplementary verification	Simple heuristic check	Attackers may mimic timestamps; limited alone
Selective SYN ACK Retransmission	Sends SYN/ACK only to clients meeting heuristics	Low	Medium	Moderate	Low to Medium	Environments with good profiling of client behavior	Reduces unnecessary SYN/ACKs; reduces load	Risk of false positives; complex heuristics required
IP Traceback and Validation	Verifies source IP authenticity using network-level checks	Low	Medium to High	Excellent	Negligible	When combined with edge network devices	Strong spoof detection; early packet filtering	Requires infrastructure support; not standalone defense