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Wake On Lan sample for C#

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4.22 (23 votes)
27 Oct 2003
Wake On Lan utility using C#.


It's strange but I failed to find on the Internet any WOL sample written in C#. So I spent some time making a program to that purpose. It's very simple but it works OK (in our intranet at least).

For waking computers, I use Magic Packet (MAC address of network adapter repeated 16 times).

The actual functionality is implemented like this:


using System;
using System.Net.Sockets;

//we derive our class from a standart one
public class WOLClass:UdpClient    
    public WOLClass():base()
    { }
    //this is needed to send broadcast packet
    public void SetClientToBrodcastMode()    
//now use this class
 //MAC_ADDRESS should  look like '013FA049'
 private void WakeFunction(string MAC_ADDRESS)   
      WOLClass client=new WOLClass();
         IPAddress(0xffffffff),  //  i.e broadcast
         0x2fff); // port=12287 let's use this one 
      //set sending bites
      int counter=0;
      //buffer to be send
      byte[] bytes=new byte[1024];   // more than enough :-)
     //first 6 bytes should be 0xFF
     for(int y=0;y<6;y++)
     //now repeate MAC 16 times
     for(int y=0;y<16;y++)
         int i=0;
         for(int z=0;z<6;z++)

     //now send wake up packet
     int reterned_value=client.Send(bytes,1024);


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Comments and Discussions

QuestionNote - you need to adjust Network Adapter power settings Pin
navyjax218-Apr-17 9:21
membernavyjax218-Apr-17 9:21 
PraiseWorks just fine Pin
Jefferson Motta6-Apr-17 5:33
memberJefferson Motta6-Apr-17 5:33 
QuestionReturn values from WakeFunction ? Pin
KeldSo7-Feb-16 4:47
memberKeldSo7-Feb-16 4:47 
GeneralWorks. Pin
Member 154943823-Sep-14 22:57
memberMember 154943823-Sep-14 22:57 
QuestionNot working on my system.. Pin
Basmeh Awad12-May-13 22:58
professionalBasmeh Awad12-May-13 22:58 
AnswerRe: Not working on my system.. Pin
Jefferson Motta7-Aug-17 5:37
memberJefferson Motta7-Aug-17 5:37 
GeneralWorks with WOW Pin
David J Rundle15-May-12 4:34
memberDavid J Rundle15-May-12 4:34 
GeneralThanks! Pin
Anthraxx NL22-Jan-10 10:33
memberAnthraxx NL22-Jan-10 10:33 
GeneralOther example and some theory Pin
memos-software24-Jun-08 20:31
groupmemos-software24-Jun-08 20:31 
GeneralError Pin
Christian Rasmussen11-Jun-08 3:11
memberChristian Rasmussen11-Jun-08 3:11 
GeneralRe: Error Pin
Ian_E15-Jun-08 12:35
memberIan_E15-Jun-08 12:35 
You are using conflicting terminology in your query. An "external machine within the network"... Which is it?

Same Subnet
If you mean a different machine on the same subnet (i.e. behind the same router):

1. Verify that the MAC address you have is correct.

2. Verify that the machine you're trying to wake supports Wake on LAN ("WOL") functionality:

2A. BIOS Settings
Go into the machine's BIOS and look for a setting that enables WOL.

2B. Is Your Power Supply Compatible?
Note that your machine's power supply must also support this capability; if your power supply does not have its own "master" on/off switch, it's likely that it's not compatible. Modern power supplies supply a trickle voltage to the computer's motherboard (in "active off" mode); this is routed to the Ethernet adapter, among other things.

2C. Is Wake On LAN Configured in Windows (Windows XP assumed below)
a) In Windows, go into Control Panel & bring up Network Connections.
b) Right-click the Network Adapter corresponding to the MAC address you're trying to wake, & click "Properties".
c) In the Properties dialog, click the "Configure..." button (next to the adapter name).
d) In the "Connection Properties" dialog, look for a Power Management (or similarly named) tab. (This may or may not be there and the name will vary, depending on the manufacturer of your Ethernet adapter & the driver you have installed.)
e) If you do have a Power Management tab, look for options that enable/disable any of the following:

- "Wake on Directed Packet"
- "Wake on Magic Packet"
- "Wake on Magic Packet from power off state"
- "Wake on Link"

These are what I have for an Intel PRO/1000 Ethernet adapter on my machine. You would need to enable the 2 Wake on Magic Packet options (I leave the other 2 disabled).

2D. Note also that for certain add-in Ethernet adapters (PCI) and mother boards you may need to connect a 3-wire "WOL Cable" (from header on card to header on motherboard) for the WOL Capability to work. You would generally find this on really old cards & motherboards (more than 5 years old).

Finally, a note about states:
S1 = On (Operational)
S3 = Standby (enable "Wake on Magic Packet" to allow wakeup from this state)
S5 = Active Off (enable "Wake on Magic Packet from power off state" to allow wakeup from this state)

Different Subnet
If you mean a machine on a different subnet and your magic packet has to be passed outside your local router, I doubt that this is possible. I have read elsewhere that routers do not forward broadcast packets. If it's a router that you control in your own domain, you *may* be able to configure it to do so - someone else would need to comment on this possibility.
GeneralRe: Error Pin
Randy_Miller12-Jul-08 6:14
memberRandy_Miller12-Jul-08 6:14 
GeneralThanks! Pin
devcow11-Jun-07 7:16
memberdevcow11-Jun-07 7:16 
GeneralWorks great ! Pin
A.J.Bauer11-Mar-07 6:32
memberA.J.Bauer11-Mar-07 6:32 
Generalfor broadcasting Pin
plato2926-Jun-06 22:16
memberplato2926-Jun-06 22:16 
Generalbroadcasting Pin
plato2926-Jun-06 21:42
memberplato2926-Jun-06 21:42 
GeneralIP Broadcasting Pin
HakunaMatada27-Dec-05 22:29
memberHakunaMatada27-Dec-05 22:29 
GeneralThanks for the sample Pin
Radoslav Bielik6-Jan-04 11:05
memberRadoslav Bielik6-Jan-04 11:05 

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Posted 27 Oct 2003


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