I have to not use "client-to-client" option in your server's config. As for iptbales, you can search this forum using google, or internet. It will be like:
iptables -A FORWARD --src 10.10.10.230 --dst 10.10.10.200 -J allow
iptables -A FORWARD --src 10.10.10.200 --dst 10.10.10.230 -J allow