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

[amki]

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