Need Linux Admin: harden server against UDP/TCP 0 traffic

Hi. Server issue. Our host nullrouted our dedicated server for "suspicious traffic". They say: We recommend you harden your server against UDP/TCP 0 traffic. I don't know what this means, as first time hearing of this in 3 years. Log: -- edge.253 [login to view URL] - [login to view URL] TCP (Flags: ACK) edge.253 [login to view URL] - [login to view URL] UDP edge.253 [login to view URL] - [login to view URL] TCP (Flags: ACK) edge.253 [login to view URL] - [login to view URL] TCP (Flags: ACK) --- They don't like to see TCP 0. Are you available for this fix?