Udp Port Null - DDOS

Hello everyone

I’m getting a very strange attack. Attack is coming without UDP port.
How can I solve this problem?

Thanks.

prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 195.230.141.238->X.Y.Z.M, len 140 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 92.39.133.73->X.Y.Z.M, len 1029 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 46.29.137.50->X.Y.Z.M, len 1500 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 51.136.14.182->X.Y.Z.M, len 49 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 46.29.137.50->X.Y.Z.M, len 140 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 51.136.14.182->X.Y.Z.M, len 1500 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 153.127.197.42->X.Y.Z.M, len 1500 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 153.127.197.42->X.Y.Z.M, len 141 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 68.231.9.254->X.Y.Z.M, len 338 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 120.138.102.49->X.Y.Z.M, len 63 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 5.58.81.180->X.Y.Z.M, len 1097 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 67.205.96.172->X.Y.Z.M, len 1500 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 97.98.10.197->X.Y.Z.M, len 58 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 67.205.96.172->X.Y.Z.M, len 178 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 200.37.108.151->X.Y.Z.M, len 1500 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 200.37.108.151->X.Y.Z.M, len 1026 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 220.158.148.243->X.Y.Z.M, len 25 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 177.85.235.166->X.Y.Z.M, len 1500 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 220.158.148.243->X.Y.Z.M, len 1500 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 31.41.93.233->X.Y.Z.M, len 1500 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 31.41.93.233->X.Y.Z.M, len 1115 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 177.139.218.232->X.Y.Z.M, len 1492 
prerouting: in:sfp-sfpplus1 out:(unknown 0), proto UDP, 177.85.235.166->X.Y.Z.M, len 1043