A system and method for defeating SYN attacks are provided. When the number of packets received by a server is above the capacity of the server, the server assumes that a SYN attack is in progress. The server randomly drops SYN packets without processing them. The percentage of SYN packets dropped is increased while the load on the server exceeds capacity, and decreased while the load on the server does not exceed capacity. Under attack conditions, a percentage of TCP connections are still maintained.