Discussion in 'LAN & WAN Article Discussions' started by thiggins, Aug 16, 2008.
Waking your PC up over the Internet can come in handy. Doug Reid shows you how.
Linksys WRT54GS and Wake on LAN
Having read Doug Reid's comprehensive article on WOL, I've just spent the week trying to get my desktop powered remotely. From with in the LAN I am able to do it, however, when I tried it over the internet it has always been a complete failure. I "slowly" re-read the article today and I believe I discovered the problem. I have been trying to send the magic packet via a notebook connected wirelessly to the internet. I was under the impression that only the host, desktop needed to be hard wired, failing to pay attention to "both the PC to be turned on and the PC sending the WOL signal need to use wired Ethernet connections". Is this indeed the problem and is there any work around? Thank You!
What's the transmission path of the magic packet?
Is it wireless notebook>Internet>home router>desktop, or wireless notebook connected to remote device (router/other PC on network) initiates sent packet to desktop?
If the former, it will likely fail as magic packets only work on the same broadcast domain.
I managed to do it.
- set the router to give a fix IP via DHCP to the computer you want to wake up
- set port forwarding on the router to the above fix IP
- send the magic packet via internet (I used HSDPA mobile net) but be careful to set the subnet mask to 255.255.255.255
I think that's all.
I read the WakeOnLan guide trying to troubleshoot a problem (http://www.smallnetbuilder.com/content/view/29941/53/1/5/), which led me here. Basically, I set up WakeOnLan on my desktop and tested it. It works fine at first, I've verified that magic packets are being received.
But then, after about 30 minutes or so, the desktop stops responding to magic packets! I know that IP addresses are lost after a certain amount of time, so I tried sending to the broadcast IP, but it still does not work. What am I missing here?
Thanks for any help,
Verry nice tutorial. thx!
This is caused by two different things.
First - you are partially correct in saying that ip addresses are lost after a certain amount of time - a more accurate way to put this is that the "ip address to MAC address" pairing is flushed from the arp cache.
ip addresses are not used for local (as in local area network) communications - the ip stack compares the destination ip address to the source ip address & subnet mask to determine if the destination and the source are on the same network, and if they are it will send the data directly to the destination using it's MAC address, if they are not, it will send the data to the router (as specified in the source hosts's routing table) using the router's MAC address, for onward routing.
Now - the MAC address of the destination host is unknown to the source so it uses a protocol called arp - address resolution protocol - to get it, and it stores that in the arp cache for an unspecified period of time - arp works like this - the PC that needs the address sends a broadcast asking "who has ip address a.b.c.d?" and the PC with that address answers.
I'm sure you see the problem here - after you switch off the computer - it cannot respond to the arp request - so after the router's arp cache is flushed the router does not know where to send the magic packet, does not get a response to an arp request, and then drops the packet.
This explains why it works when the computer is first switched off but after a few moments will stop working.
The fix is to send the magic packet to the LAN's broadcast address which SHOULD cause the router to broadcast it to all hosts using the broadcast MAC address - but - as you discovered this does not work either.
Most consumer routers do not allow "ip directed broadcast" which is what is required for you to send a broadcast packet from the WAN side to the LAN side - this is a security issue and a potential attack vector that can be used to hack systems on the inside of the LAN as well as to use those systems in denial of service attacks (smurf attacks) on other targets.
ARP cache - how to check it it is flushed or keeped ? I own a canyon Wf 514 router, wher the desktop is connected over wired lan. When I try wakeOnLanGUI in the lan, it works without any problems, but if I send this signal over wan it works only a couple of minutes after something is changed in the configuration of the router, after that - not. Please help me with this issue. Thank you in advance
I have understood that the arp cache is dynamic and is loosed after a couple of minutes. Is there a possibility to add static arp record in the router CN-WF514 ( canyon ) so I can send WOL request from WAN to this computer in the LAN?Thank you in advance
Assuming 192.168.1.1 is the address for your router,
Try this from command prompt: telnet 192.168.1.1
then: arp -s 192.168.1.64 00:00:00:00:00:00
In the above example, the ip address is the address of the PC you want to wake. And what follows is the MAC address. This worked for my Actiontec GT704WG. Basically, I did a search for ARP Actiontec. Good luck.
arp for wrt610N
I'm having the exact same problem with my WRT610N. Looking for alternative solutions though ... router doesn't support telnet to 192.168.1.1 and it only seems to support reserving IPs through DHCP.
I to am having the same the problem and its driving me insane!
I am able to shutdown my PC using RD and immediately after send a magic packet to wake the PC up, however after a few minutes, the WOL stops working and my home pc no longer responds to the UDP magic packet.
I thought it might be that my NW adaptor looses its power after a few minutes and does not respond from the shutdown state.
What is confusing is that nearly all advice on the web recommends:
1) To tick - Allow the computer to turn off this device to save power
2) To tick - Allow this device to bring the compuer out of standby state
3) To Tick - Only management stations can bring the computer out of standby.
Do you happen to know if:
Ref (1). Disabling this will switch off all power save functions including automatically switching off the network card after a period of time? With this NOT ticked, should the power to the network card always be present?
Ref2: If (1) is not ticked, windows will not allow you to select (2) & (3), it greys them out.
My other question is which ACPI S states are support with WOL (S1, S2, S3 ETC..)
Do you think it might be easier for me to; instead of shutdown my home pc, to hibernate / sleep etc..
Any help would be greatly appreciated.
My router also does not allow a telnet session.
I found the soloution here, for the same problem:
Opened port 7 for 192.168.0.255 instead of 192.168.0.100
Solution for some routers here
WOW solution on Netgear WPNT834
I've got a Netgear WPNT834 (that will be replaced this week by a Linksys WRT610N). The Netgear doesn't accept a broadcast on .255 like most other ones. What I did (picked up on a forum a few years ago) is the following:
1) Changed the DHCP server IP end address to xxx.xxx.xxx.126
2) Set the subnet mask on xxx.xxx.xxx.128
3) Created a UDP port-forward for port 7 & 9 to IP xxx.xxx.xxx.127
Does work stable on 3 comp's like a charm (apart from the instable performance on high WAN speeds [60Mbps +] and a whole bunch of other problems )
Seen the issues mentioned on current servers I’m planning to do something similar on the Linksys.
WRT610N now operational for more than a week.Tried all sort of things but does not get WOL over WAN to work . Even things like changing the .asp and Java code have not turned out to be succesfull yet. It seems that Linksys has built-in broadcasting prevention on different levels. If you are able to take one hurdle you jump in to the next. I'm just feeling like Alice in Wonderland but I keep working on it
How To Wake on LAN / Wake on WAN
I have been trying to send the WOL magic packet over the WAN to wake up the computers in the remote office. I put the following config on our Cisco 2600 routers but it doesnt work as expected.
ip forward-protocol udp 60000
Did I miss anything?
Question about WOL
I have a small question concerning the WOL command.
Is it possible to send instructions with the WOL call?
For example: On boot I would like to have 2 possible boot options:
1. Boot Windows normally (Default)
2. Boot on network and configure a new image on the machine
Now, it would be nice to be able to send a message during the WOL, that told the machine to use boot sequence number 2, but whenever the user turned on the computer it would be boot sequence 1. Is there a way to do this using WOL??
Thiggins, can you try to figure out how to solve this issues with linksys routers and Wake On Wan now than you have the E3000 to toy with?
No2 Vaporizer Review
I pursued WOL pretty heatedly for my data servers and came to the conclusion that it's a technology that's not ready for prime time. It works some times, with some hardware, and in some setups. Sometimes it works great. Sometimes no amount of hacking and learning will make it work. I'm not a networking expert, but I know some from my previous career. Their comments amounted to what I just said.
And then there are some motherboards which don't do it, and some OS's which don't support it even if the motherboards and BIOSes do.
This is what led me to do the remote button pushers. My first was an autonomous ethernet controlled AC power strip with four independently controllable AC outlets. That solves the "wake" part; just turn on the power, having previously set BIOS to startup on power available. But it's brutal on power down. Hence the remote button pushers. I cobbled together and tested a couple of versions of button pushers which work by being AC-outlet-controlled, so I could soft-off machines with the controlled power strip.
I have now received what I think is a better solution, and will put it into test as soon as time permits.
A Korean company called Wiznet (www.wiznet.co.kr) makes a widget which is a small self contained web server that gives you eight digital outputs, eight digital inputs, two analog ins and two analog outs, all accessible from that ethernet jack. The $50 WIZ220IO, if it works as advertised, will enable me to use the opto-isolated button pusher circuits from my blog to network "press" the power switch and/or reset switch on controlled machines from anywhere on the net.
This sidesteps the issues of BIOS setup, motherboard compatibility, network layers, PME events, magic packet senders and so on. It leaves the issues of messing about with the setup on the WIZ220IO, but we'll soon see how complex that is.
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