iptables -A INPUT -p tcp \
-s ${CLIENT_SERVER_IP} --sport 1024:65535 \
-d ${SERVICE_SERVER_IP} --dport ${YOUR_SERVICE_PORT} \
-m state --state NEW,ESTABLISHED -j ACCEPT

iptables -A OUTPUT -p tcp \
-s ${SERVICE_SERVER_IP} --sport ${YOUR_SERVICE_PORT} \
-d ${CLIENT_SERVER_IP} --dport 1024:65535 \
-m state --state ESTABLISHED -j ACCEPT