OS X Server Messages Server Jabber Proxy65 File Transfer Solution

Like many others, I'm running OS X 10.9 Server behind NAT, and finding that Messages (aka iChat) which uses Jabber/XMPP is hit-or miss when doing file transfers between LAN and WAN clients.

The solution I found was here: messages server proxy65 behind NAT?

The problem : by default, the proxy65 config (which handles Jabber file transfers) binds to the server's IP address. In a NAT setup, this would be a LAN address. When the file transfer initiates, this LAN address is advertised to the clients, and if they are on the WAN, it's not a routable address.

You might think you could use the WAN IP address instead - but this fails within the proxy65 setup with this error:

twisted.internet.error.CannotListenError: Couldn't listen on 64.XXX.XXX.XXX:7777: [Errno 49] Can't assign requested address.

The solution, as per the post, is to comment out one line in the proxy65.py file and use an actual DNS name in the com.apple.proxy65.plist file.

Although that solution was written for 10.6 this seems to work well for me in 10.9.