Firewall for TFTP Proxy

[alivdel]

Hi,

as I searched packet via TFTP client will be sent on server through port 69 but server will answer on random port.

i activated TFTP proxy on LAN and WAN and made firewall rule to pass udp packet on port 69.
with this rule packet send back from server will be blocked beacuse it comes on different udp port.

now question is how can i define a firewall rull to make it happen. (a firewall rule to allow all udp port pass through is not an option)

thanks.