When you’re done, here’s how this will work:

1. From wherever you are in the world, navigate to your unique, dynamically updating URL 
1. (example.dyndns.org:5000)
2. You’ll be presented with a screen that looks like this:
   
3. Next, you’ll enter a passphrase that you’ve pre-allowed. If the wrong phrase is entered, a “denial” note will pop                       up, and you’ll be able to try again. If you enter the right phrase, the Raspberry Pi will send a Wake Up                     command to the network interface of the computer that you want to wake up. It will then ping that computer                     and display the results in real-time, so that you know when the computer has finished booting and is                     accessible. That screen looks like this:
   
4. Once you’ve received confirmation that the computer is alive, you can access it as you normally would,                   depending on what you’re doing (via SSH, FTP, or Windows Remote Desktop, for example).

For the purposes of the following explanation and tutorial, I’ll define a few terms:

• Remote Computer: This is the “power-hungry” computer located on the same network as your                     Raspberry Pi. I’m assuming you are using a hardwired Ethernet connection, since Wake-On-LAN                               (WOL) does not work over Wi-Fi.
• WOL Sever (Raspberry Pi): This is the low-power, always-on, micro server that will be running on the                  same network as the remote computer. You don’t have to use a Raspberry Pi; any low-power platform                 capable of serving up web pages, running PHP, and sending Wake-On-LAN magic packets will work fine.
• Client: This is the computer, phone, or other web-connected device that will view the WOL control                   webpage.
• Router: I assume you are using a home router with a fairly standard feature set, and that you have                   administrative access to it. It should support DHCP address reservations, NAT port forwarding, and                       ideally support for a dynamic DNS updating service (like DynDNS or NoIP).
• Dynamic DNS Service: This is a service that handles redirecting a URL to your home’s dynamic IP                     address. Since most ISPs assign dynamic WAN IP addresses, you need to use a service like this to                     ensure you can maintain access to your home network, even when the externally-facing IP address                 changes.

Here’s what you need to do to get this working:

• Ensure that the remote computer supports Wake-On-Lan (WOL) functionality. You may need to boot into the                 BIOS and permit the computer to be woken up via the network interface. This will look different on nearly                    every BIOS. LifeHacker has a good tutorial showing how to enable WOL functionality. For a shortened                         version specifically for this tutorial go here. 

• Setup your Raspberry Pi with a linux distribution if you haven’t already, and get it connected to your network.               Adafruit has a great set of tutorials that can help you do the initial setup for your Raspberry Pi. I made a                  condensed version on one webpage here. (Note: some instructions are for older version but I was able to find                my way through everything ).

• Log into your Router’s administration panel (in most scenarios you can do this by visiting your Gateway IP              from your browser). Find the status page and locate the listing of attached clients. Identify your Raspberry                 Pi and your computer by their hostnames, and copy down their MAC addresses, and IP addresses. In the                  screenshot below, the hostname of the computer I want to control is “PHOENIX” and the Pi’s hostname is, appropriately, “raspberrypi.” This will vary by router, but the listing will look something like this (Note: I blurred             out some of my personal info):

1. Now, find the “DHCP Reservation” or “Static Leases” list in your router’s administration panel. You’ll configure                        your router to always assign your remote computer and the raspberry pi the same IP address every time they                     connect to the network. This ensures that you’ll be able to reliably forward data to them through the router.                             It will look something like this:
   
2. Next, find the port forwarding configuration screen in your router’s administration panel. You’ll want to route                    HTTP data to the raspberry pi, and any remote service ports that you want to access to the remote computer.                    Importantly, many ISPs will block incoming traffic on port 80, the default HTTP port, to prevent customers                            from hosting websites from their residences. But, you’re smarter than they are! Simply route an arbitrary                              external port, to the internal port 80 on your Raspberry Pi. In the screenshot below, you can see that I am                        routing external port 5000 to internal port 80. This means that when you eventually access the WOL server,                          you’ll need to specify the port, like this: . Route the appropriate port for whatever services you want to access                      on the remote computer. In the screenshot below, I’ve routed port 3389, which is what Window’s uses for                  Remote Desktop. If you wanted to access an SSH server or SFTP server running on the remote computer,                        you could additionally route port 22. You can find a listing of ports used by various services on wikipedia.
   
3. Next, you’ll want to sign up for a dynamic DNS updating service that your router supports. Different routers                           support different services and most likely will require DDWRT installed to configure. If you have an Apple                               Airport Extreme or Time Capsule then this is not an option. That is why I chose to create this tutorial since I                         got rid of my router with DDWRT. 
1. Follow my guide here if you want to also use your raspberry pi to configure and autoupdate your                             DynDNS.
2.  Sign up for a free account, and get a URL that looks something like this: yoursite.no-ip.org. NoIP                              even supports port 80 redirects, so you can configure your account to not require appending the                                non-standard port number to the end as described in the last step. Once you’ve got your dynamic                              DNS account, find the Dynamic DNS (DDNS) updating screen in your router’s administration panel,                            and enter your account info. Now, you’ll always be able to access your home network, without                          knowing the IP addresses, and the router will handle automatically updating where the URL directs                             when your dynamic IP changes!
   
4. Now that your router is all set to handle everything, it’s time to get the Raspberry Pi setup. Access your                   Raspberry Pi over SSH and log in with the username (pi) and the password that you configured when you                         followed the setup tutorial linked from step 2 (ssh pi@192.168.1.132). You’ll need to install WOL software                         and a webserver. Enter this command at the terminal to do so:
   pi@raspberrypi ~ $ sudo apt-get install wakeonlan apache2 php5
   Now, navigate to the webserver directory (/var/www) and clone my Remote WOL software from my github                 repository:
   pi@raspberrypi ~ $ sudo apt-get install git
   pi@raspberrypi ~ $ git clone https://github.com/sciguy14/Remote-Wake-On-LAN-Server.git
   pi@raspberrypi ~ $ sudo chown pi /var/www
   pi@raspberrypi ~ $ sudo chgrp pi /var/www
   pi@raspberrypi ~ $ mv Remote-Wake-On-LAN-Server/* /var/www
   pi@raspberrypi ~ $ rm -rf Remote-Wake-On-LAN-Server/
   pi@raspberrypi ~ $ rm -f /var/www/index.html
5. Now, you’ll need to adjust the configuration settings so that they work with your particular network setup.                   Rename config_sample.php
   to config.php. Then, open it for editing with a terminal editor such as nano or vim:
   pi@raspberrypi ~ $ mv /var/www/config_sample.php /var/www/config.php
   pi@raspberrypi ~ $ nano /var/www/config.php
   Follow the instructions in the file to set your passphrase hash, the local IP/MAC for the computer to wake up                       , and the ping retry value. When you’re done, save and close the file.

Update (7/15/2013):

Update (7/20/2013):

1. Install Curl on your Raspberry Pi for PHP
   pi@raspberrypi ~ $ sudo apt-get install php5-curl
   If it doesn’t work, you might need to update your repositories first:
   pi@raspberrypi ~ $ sudo apt-get update
2. Download the Sleep on LAN software and run it on your windows computer. Set it to launch at boot so that                         it will always be ready to go.