Wake On Lan not working Over UDP

CodeBlox

I wrote two simple programs in C that send the magic pattern for WOL. One of the programs sends the magic packet straight over ethernet and that one works. The other sends it over UDP and I am using UDP port 9. I have tried several ports but the machine does not wake up using UDP. I know the packet is getting to the PC as I confirmed that with wireshark. It's a unicast datagram sent from my PC at work to my home PC. I know WOL should work over UPD according to research.

EDIT: I suspect that I know why it's not working... The packet should be port forwarded to the LAN broadcast address and my DLINK does not support that. I had it forwarding to the unicast address and the packet gets received whereas it doesn't when forwarding to the broadcast... Oh well :P

NovaHax

I built a WOL tool that operates over TCP with Scapy (my c kung-fu is not so good). But it doesn't have to be sent to the broadcast address. My TCP function sends it directly to the host.

I haven't tested it over UDP...but I see no reason why it wouldn't work. I'll try to modify mine tonight and let you know what I get. It will be way easier for me to modify my fairly short scapy script than for you to have to recode a C program.

About7Narwhal

Why not leave it at TCP if that works? Perhaps I am missing something?

NovaHax

Is your home system on a public IP? Or are you using port forwarding to get to it?

CodeBlox

About7Narwhal wrote: »

Why not leave it at TCP if that works? Perhaps I am missing something?

I'm not using TCP. Since NovaHax advises that it works using TCP, I think I might make revisions at some point tonight and try that out. My home PC gets natted to a public IP. What I have done is setup a port forward for the specific port to the PC. I can confirm that the packet gets to the PC using wireshark if its unicast.

NovaHax

Just looked back at my script and found that I was mistaken. I did use UDP port 7.

Packet stack should be
IP / UDP / Raw

For IP, I used the public IP address of the host as the destination IP. I've only tested mine on public addresses (so you add an additional variable here).

For UDP, I used the destination port of 7. I think most systems configured to respond to Wake-On-LAN will listen on both 7 and 9...so you should be good.

For raw data, I included ('\xff'*6) and then 16 instances of the system's MAC address, hex-encoded.

Hope that helps.

NovaHax

Here it is in Python (this script assumes you have Scapy installed):

---

from scapy.all import *
import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)

lay2addr = raw_input("Enter MAC address(Example - 000c2991e3b2): ")
mac = lay2addr.decode("hex")
ip = raw_input("Enter IP address (Example - 192.168.74.141): ")
send(IP(dst=ip)/UDP(dport=7)/Raw(('\xff'*6)+(mac*16)))

networker050184

About7Narwhal wrote: »

Why not leave it at TCP if that works? Perhaps I am missing something?

What would be the fun in that?!

NovaHax

7 lines of code...which would probably amount to 100+ in C :-/

NovaHax

But now I'm curious if it would work over TCP???

CodeBlox

haha... Here is my source code in C. I could do the same thing in Python with much less effort but I get so stuck in my ways of C. I like to keep my programs modular and the multiple files make it look longer than it really is. Not necessary, just my preference.

wol.h

#ifndef WOL_H
#define WOL_H


#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>


#include <netinet/ether.h>
#include <netinet/in.h>
#include <sys/socket.h>




#define MAC_ADDRSTRLEN 17
#define WOL_DATA_LEN 102
#define MAC_ADDR_LEN 6


#define BROADCAST_STR "ff:ff:ff:ff:ff:ff"


void get_params(char *, char *, char *, int, char **);
void wol_err(char *);


int wol_sock();






#endif 

get_params.c

#include "wol.h"


void get_params(char * inet_addr_str, char * mac_addr_str, char * port, int argc, char ** argv)
{
  
  char optc;


  while((optc = getopt(argc, argv, "m:p:i:")) != -1)
    {


      switch(optc)
    {


    case 'm': 
      //memcpy(inet_addr, optarg, INET_ADDRSTRLEN);
      strncpy(mac_addr_str, optarg, MAC_ADDRSTRLEN);
      break;
    case 'i':
      strncpy(inet_addr_str, optarg, INET_ADDRSTRLEN);
      break;
    case 'p':
      //memcpy(mac_addr, optarg, MAC_ADDRSTRLEN);
      strncpy(port, optarg, 6);
      break;
    case '?':
      exit(EXIT_FAILURE);
    
    }


    }


}

wol.c

#include "wol.h"


int main(int argc, char ** argv)
{


  int raw_sock, iteration = 0;
  struct ether_addr * mac_addr;
  char inet_addr_str[INET_ADDRSTRLEN], 
    mac_addr_str[MAC_ADDRSTRLEN], 
    port[6],
    data[WOL_DATA_LEN];
  
  struct sockaddr_in peer;
  
  if(argc == 7)
    get_params(inet_addr_str, mac_addr_str, port, argc, argv);
  else{
    printf("argc = %d\n", argc);
    wol_err("Usage: ./wol -i x.x.x.x -m xx[IMG]https://us.v-cdn.net/6030959/uploads/images/smilies/icon_mad.gif[/IMG]x[IMG]https://us.v-cdn.net/6030959/uploads/images/smilies/icon_mad.gif[/IMG]x[IMG]https://us.v-cdn.net/6030959/uploads/images/smilies/icon_mad.gif[/IMG]x[IMG]https://us.v-cdn.net/6030959/uploads/images/smilies/icon_mad.gif[/IMG]x[IMG]https://us.v-cdn.net/6030959/uploads/images/smilies/icon_mad.gif[/IMG]x -p xxxxxx");
  }


  raw_sock = wol_sock();
  
  peer.sin_family = AF_INET;
  peer.sin_port = htons(atoi(port));
  
  if(inet_pton(AF_INET, inet_addr_str, &peer.sin_addr) != 1)
    {


      wol_err("inet_pton:");


    }




  memcpy(data, (struct ether_addr *)ether_aton(BROADCAST_STR), MAC_ADDR_LEN);


  mac_addr = ether_aton(mac_addr_str);
 
  for(iteration = MAC_ADDR_LEN; iteration <= 96; iteration += MAC_ADDR_LEN)
    memcpy(data + iteration, mac_addr, MAC_ADDR_LEN);


  if(sendto(raw_sock, 
        data, 
        WOL_DATA_LEN, 
        0, 
        (struct sockaddr *)&peer,
        sizeof(peer)) == -1)
    {


      wol_err("sendto:");


    }


  return 0;


}

wol_err.c

#include "wol.h"


void wol_err(char * wol_err_str)
{


  fprintf(stderr, "%s\n", wol_err_str);
  exit(EXIT_FAILURE);


}

wol_sock.c

#include "wol.h"


int wol_sock()
{
  
  int wol_sock = 0;


  if((wol_sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
    {


      wol_err("socket: ");


    }
  
  return wol_sock;


}

NovaHax

God :-/...I envy and pity you at the same time, lol

CodeBlox

I think I'll try coming up with a TCP implementation tonight or tomorrow which will require a raw socket and will cause me to have to craft the entire packet myself since a SOCK_STREAM socket must be "connect()'d" before it will be usable for read/writes. I'm interested in seeing how it plays out. I'm not really expecting the TCP implementation to work but who knows, I might be surprised.

NovaHax

Yeah...that's what's nice about scapy. It is very easy to defy conventional usage. **as opposed to Python's socket library**