corsairetc - 2013-10-17

Hello,
recently I was configured Firewall witj two interfaces internal network using nat with dns and dhcp eth0(192.168.3.254)and exxternal network net access eth2(192.168.5.249).
Everything works fine but one thing I am not able to make. I want to ping from network 192.168.5.0 to nated internal network 192.168.3.0 reverse ping from 192.168.3.0 is work.
Could you help me please which rule I can configure.