server Attack

[kokonat]

hello first of all sorry if my english is not so good. i see friends share troubles with their call of duty 2 servers and im in trouble wanted to say here if anybody pls can help me . im having a windows server and i have a server with no mods sometimes someone attacking and its like this you can see in screenshot spamming and lags server

i recently had this problem and asked a polish modder he said your exe must have getchallenge fix need to edit some codes but i dont know which codes must be edited .i wanted to say here maybe professional users can help me . thank you