NAT and port forwarding in OS X 10.4

Hi,

I configured Xserve as gateway using dual-homed function, one ethernet connected to Internet directly, another one connected to internal LAN (192.168.1.1),

en0: 192.168.1.1

en1: external IP

I updated natd.plist as follows in /etc/nat directory:

<key>redirect_port</key>

<array>

<dict>

<key>proto</key>

<string>tcp</string>

<key>targetIP</key>

<string>192.168.1.2</string>

<key>targetPortRange</key>

<string>80</string>

<key>aliasIP</key>

<string>external IP</string>

<key>aliasPortRange</key>

<string>80</string>

</dict>

</array>

natd.plist.apple file is also ok, but Xserve cannot redirect to 192.168.1.2 web server, user only reach Xserve web page from outside, can everyone tell me what is going on? You help would much appreciated.