[imported_admin]

Yes, you can use 80 in the client.xml, because you redirect the:
x.y.z.w port: 80 --> 192.168.1.100 port: 51127
the real port of the server listen is 51127, it's between 1024-65535


But, I'm wondering, the 80 port is the default http port, if you redirect the 80 port , how about the www access ? is there another port is not blocked you can use ?