I use OpenWrt whiterussian (0.9) with miniupnpd 1.0-RC5. On the macbook I use Transmission.app for torrents. The problem is that it maps the port successfully but reports the port (9090) as stealth. I finally fixed this nagging issue with this command:

iptables -t nat -I PREROUTING -p tcp --dport 9090 -j DNAT --to-destination 192.168.1.172

Now Transmission.app says the port is Open.

Here's the relevant iptables listing:

root@OpenWrt:~$ iptables -v -t nat -nL |grep 9090
188K 9893K DNAT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:9090 to:192.168.1.172:9090-0
187 11636 DNAT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:9090 to:192.168.1.172


The first line was added by miniupnpd. Not sure what the -0 is there for.