I bought the highly spoken of (scroll down here) Buffalo WHR-G125, which is cheap and flashed it’s software so I can use dd-wrt. I did this from a mac following the directions, but in the end I had a tough time getting the timing right. So this posting’s purpose is to explain how to get the timing right.

I used two tricks. The first is to use expect to script tftp. The second is ignore the instructions (which say to launch the upload when the lights on the router indicate that the single LAN Ethernet your using to connect to it is now active). Instead I wait until the Mac’s brings up it’s interface.

My expect script looked like this:

#!/usr/bin/expect -f
set  timeout 3000
spawn “tftp”
expect “tftp> “; send “binary\n”;
expect “tftp> “; send “rexmt 1\n”;
expect “tftp> “; send “connect 192.168.11.1\n”;
expect “tftp> “; send “put dd-wrt.v24_std_whr-g125.bin\n”;
expect “tftp> “; send “quit\n”;

You use this command to run that.

 % expect flash_it  

That’s pretty straight forward and expect is installed on the mac if you have unix tools, which your likely to if your flashing routers in your spare time. You invoke it like so:

It’s easy to see when the Mac bring up the network connection to the router. When you set things up following the instructions you configured the your network to talk to the router. Open that system preferences up again and stare at the TCP/IP page. You can monitor that page to see the connection to the router come up; first the Ethernet is sensed and a moment latter the IP address is configured; it’s at that point you hit return on the command above.

HamachiX is a Mac OS X application for casually creating “virtual” private networks connecting random computers. It’s implemented by wrapping some user interface around the no charge variant of the proprietary Hamachi VPN product. The VPN(s) it creates are named. The machines that join that network providing an appropriate password and get IP addresses like 5.85.1.2. At which point they may exchange data packets with each other. Hamaci is clever in that it uses p2p tricks to bust thru firewalls.

A typical application is to create a community of users who share iTunes collections, or printers, or whatever.

I’m using this to create http listeners on machines which sit on the public network that then forward to listeners on my laptop. When ever my laptop manages to get on the network Hamanchi rejoins the appropriate network and the forwards start working again. This allows me to demo things running my laptop to random folks on the network at large. I do the port forwarding with balance (sudo port install balance).

It looked like I could do something similar with tinc and avoid the issues raised by using proprietary software. But, MacPorts doesn’t include tinc and this certainly was easy. There are lots of choices for how to forward the listener, as I am with balance. I’d be curious to hear of how other people do this kind of thing?

Update: This widget is an alternative to HamachiX once you get started. You can do all this on the command line, say on 10.3.9.

Update 2: Some people find that HamachiX goes crazy and consumes vast amounts of memory.  A problem you can work around by using it as a easier way to install things and then use the widget or the command line tool hamachi from there on in.  The command line tool gives you a better model of what’s really going on.
I’m finding it dependable for simple tcp/ip connections; but mDNS is spotty.  The forums are full of complaints about various non-working scenarios and some of those are real v.s. user confusion.  One of the foundation pieces, tuntap, is also known to occationally misbehave on intel macs.