[tor-relays] How to protect yourself from network scanning

Hiho, I am hosting a 3-5MB/s tor exit relay but as of today my hoster has closed my server because of network scanning. Is there a known proper way to protect yourself from being used as a network scan relay? I've thought about constructing iptables rules to limit the number of SYN packets for the same host per second or such, but I'm not sure if this is allowed or will get me flagged as a bad exit node. My hoster is quite ok with us generating some abuse complaints per month, but does not want to route network scanning traffic since it is a severe load to their routers. Any help would be appreciated Cheers amki -- "Whatever the reason you're on Mars, I'm glad you're there, and I wish I was with you." - Carl Sagan