Networking – Is automatic Wake On LAN possible with DD-WRT

networkingwake-on-demandwake-on-lan

I might be thinking the wrong way to solve this problem. If there's a better way, than tell me. I want to be able to allow my home server to sleep when it's unused, but to automatically wake up when it's accessed. My household doesn't follow a set schedule due to people working different shifts, so I can't schedule an optimal sleep/wake cycle for the server

There is a WOL daemon for DD-WRT that sends out wake up packets on a scheduled interval, but this is not what I want. I would like for my home server to automatically sleep, but also automatically wake up when it is accessed.

I do not want to use any kind of utility to explicitly send a wake-up packet. I have the server mapped to static IP address. I would like to know if any solution exists that would automatically send wake up packets if the static IP was considered unreachable due to the the computer being in a power-savings mode.

Best Answer

This guy might be doing what you're asking:

http://gaddgets.blogspot.com/2007/02/auto-wol-on-dd-wrt-on-linksys-wrt54gl.html

I thought I would try to set it up to wake up the computer on a Port 80 (http) access if it was in "sleep" mode. ... I would parse the syslog to detect port 80 activity. ... There is a lag now, when the computer is asleep to access a page on the computer. However I find that in most cases, the browser timeout is long enough to wake the computer up and deliver the webpage.

The script he wrote is at that link. If you're accessing on another port, change the port I suppose.

Related Solutions

Linux – ethtool, WOL: What does “wake on physical activity” actually mean and (how) can I use it

Note: the question is a 4+ year old cross post from here. Not sure why it gets a bounty after more than 4 years, but probably it received a wol package ;-)

The ethtool manual says:

wol p|u|m|b|a|g|s|d...
          Set Wake-on-LAN options.  Not all  devices  support  this.   The
          argument  to  this  option  is a string of characters specifying
          which options to enable.
          p  Wake on phy activity
          u  Wake on unicast messages
          m  Wake on multicast messages
          b  Wake on broadcast messages
          a  Wake on ARP
          g  Wake on MagicPacket(tm)
          s  Enable SecureOn(tm) password for MagicPacket(tm)
          d  Disable (wake on nothing).  This option clears  all  previous
             options.

The PHY activity refers to the PHY chip, that handles communication on the physical layer of the OSI model. In laymans terms: any package directly send to this networking device should wake the machine up.

The following conditions should be met before wake on PHY works:

your networking device supports this and your networking driver supports this. I'm not sure if ethtool is checking this extensively before setting the parameter. Check your manual/spec's to see if this specific feature is supported.
your ethernet card is still on after shutdown (led lights should be on). If this isn't the case, make sure that your OS isn't shutting down the card (in most Linux distro's put NETDOWN=no in /etc/default/halt).
wol settings are preserved after sleep/shutdown.
wol is enabled in your BIOS settings.

Also note that the default arp timeout is 30 seconds (also see this SU post). After that, the ip address of your target machine will be forgotten by the machine from where you are sending any physical package. Make sure you set a static arp address on the machine from where you are sending the package.

Now any directed request (ping, http, ssh, a wol package, ...) should bring your machine up.

Wake-On-LAN – How to Configure Behind Two Routers

WOL packets need to be issued from the network the machine to be woken is on. They are sent to a MAC address and so cannot be routed across networks - they cannot be forwarded by routers from one network to another. Is the dd-wrt router on the same network as the PC?

If so, you could issue the wol packet from the dd-wrt router

Best Answer

Related Solutions

Linux – ethtool, WOL: What does “wake on physical activity” actually mean and (how) can I use it

Wake-On-LAN – How to Configure Behind Two Routers

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