In order to use the iPhone Hotel Room Baby Monitor setup I described in part 1 in situations when you’re not behind a friendly router (such as in an actual hotel room), a little advance preparation is required. You’ll need a computer on your home network that you can leave on (or one that you already do) . That computer will need to be running an SSH server (sshd). You’ll also need to know the public IP address of your home network, that is, the IP address assigned by your ISP to your router that’s serving as your home’s internet gateway. Lastly, you’ll need to forward ports for both SSH and the audio stream from your router to your always-on computer. If you’ve got all of that, you’ll be able to establish a secure tunnel from your home to your laptop, and expose your audio stream to the internet, and thus to your iPhone.
As before, I’ll illustrate by using my own equipment, and leave it to you to adapt the instructions to your setup.
I have a Mac Mini at home that I keep running all the time (set to never sleep or spin down the hard drives). In its System Preferences -> Sharing panel, I have enabled Remote Login, which runs sshd, the SSH server.

System Preferences, Sharing tab
This allows my Mac Mini to accept SSH connections using a valid username and password for this computer.
To connect to this computer from outside my home network, I’ll need to know how to reach my home network from the internet. You can find the IP address by checking your router’s administration utility (usually just a web page at its LAN address); typical names are “WAN address” or “Internet address”. Consult your router’s documentation for guidance here. Mine is right on my router’s main dashboard page.

Locating your internet IP address
Now keep in mind that with most ISPs, unless you’re paying extra for a static IP address, this address will change periodically. We’re not talking that frequently, so if you check the address before you leave, you’ll probably be okay, but no promises. Alternatively, you can (and should) use a free service like the excellent DynDNS to track your dynamic IP, allowing you to use a consistent and easy-to-remember domain name (such as yourname.dyndns.org) instead of a periodically changing set of numbers. It doesn’t take much to get the service running, and it’ll simplify your life if you regularly need to access your home network from the road.
Now you know how to reach your home router, but how to get to your computers behind the router? This is accomplished through another feature of your router called port forwarding (or “enable applications” or some other term; again, check your documentation). You’ll need to forward TCP connections on port 22 to port 22 of the computer you always leave on, and TCP connections from port 8000 to port 8000 of the computer you always leave on. (You may choose to use different port configurations if it suits your needs; those to whom this applies don’t need me to tell them.)
With all of this preparatory work, the magic can happen when you’re on the road. Let’s say you’re out at your hotel room and want to launch the iPhone Hotel Room Baby Monitor. You have Nicecast running as described earlier. Now, open Terminal (in Applications/Utilities) and type the following to make the SSH connection and establish the tunnel from your home to your laptop:
ssh your_username@your_home_ip_address_or_domain_name -R 8000:localhost:8000
If you’ve never connected before, you’ll get a warning. Accept, then provide your password, and you’ll be treated to a command line prompt from your home computer. You won’t need that, so just minimize but don’t close that window (if you close it, the connection will be broken, and you’ll need to reconnect). The SSH server at your home is now dutifully passing all requests to listen to its own port 8000 to port 8000 of your laptop, which not coincidentally just happens to be where Nicecast will be providing the audio stream. And because your home router is also forwarding port 8000 requests to port 8000 of your home computer, pointing the Tuner application on your iPhone to your_home_ip_address_or_domain_name:8000 will play the audio stream generated from your laptop (by way of your home computer and router). Awesome!
Granted, there are a lot of parts here, and it might be daunting to a novice. But this is very useful stuff to know for a variety of potential uses with many other applications. And feel free to shoot me an email or leave a comment if you have a question. Also, you can test your setup while still at home, just to see if it’ll work before you’re outside of your home network and have no way of fixing it. Just make sure that when you test, you configure your router’s port forwarding for port 22 and port 8000 before you launch Nicecast. If you don’t, Nicecast may configure your router automatically, pointing 8000 right to your laptop, leaving out the other computer entirely. That’s convenient when at home, but that’s not how it’ll work when you’re on the road, so get that port forwarding configured as described above so it’ll be usable when away from home.
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