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From: jeff@hpfcmgw.HP.COM (Jeff Taylor)
Newsgroups: comp.sys.hp
Subject: Re: How to get Ethernet Address
Message-ID: <17780030@hpfcmgw.HP.COM>
Date: 10 Jun 91 19:07:51 GMT
References: <899@bcstec.boeing.com>
Organization: HP Fort Collins, CO
Lines: 47


> How does one programmaticcaly ascertain the machine address
> (the 6 byte code of the communications card) of a connected peer.

I think this will help. No promises. 

Jeff Taylor
#include <std_disclaimers.h>

--------------------------------------------------------------------------

/*
 *  Example code to show the use of an ioctl to fetch the ethernet address 
 *  of a workstation.  The 48 bit address of the local Ethernet/IEEE802 
 *  device is returned in arg.value.s.
 */
#include <netio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

static char *hex="0123456789ABCDEF";

main() {
  int fildes,request;
  struct fis arg;
  int i;
  char addr[15];

  fildes=open("/dev/lan", O_RDWR);
  request = NETSTAT;
  arg.reqtype = LOCAL_ADDRESS;
  if (ioctl(fildes,request,&arg)<0) {
    printf("netstat failed\n");
    exit(-1);
  }

  /* convert the address into a string of hex characters and print. */
  addr[0]='0';
  addr[1]='x';
  for (i=0; i<6; i++) {
    addr[i*2+2] =   hex[arg.value.s[i] >> 4];  /* high nibble of i'th byte */
    addr[i*2+3] = hex[arg.value.s[i] & 0x0f]; /* low nibble of i'th byte */
  }
  addr[14]='\000';
  printf("ethernet address is %s\n",addr);
}