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SubjectRe: Solution to the "1802: Unauthorized network card" problem in recent thinkpad systems
On Sun, Jun 13, 2004 at 12:39:50AM -0700, Tisheng Chen wrote:

> In recent IBM thinkpad systems, there is a limit to
> allowed MiniPCI wireless cards. When an unauthorized
> card is plugged in, the system doesn't boot and
> halt with an error message like:
> 1802: Unauthorized network card is plugged in
> Power off and remove the miniPCI network card.


> The other way is unbelievably simple. There is a byte
> in CMOS which controls whether an "unauthorized" card
> is allowed or not. That's 0x6a, actually only
> the bit 0x80. The program to unlock the authorization
> mechanism is like (asm):
> MOV DX,0070
> MOV DX,0071
> OR AL,80
> MOV AX,4C00
> INT 21
> The program can be downloaded from:
> To use this program, you need to boot to DOS.
> The CMOS solution is safe, but I'm not sure that it
> works for all recent thinkpads and all cards. The BIOS
> crack sure does, however it is difficult
> and dangerous.

Well, here is a version for Linux:


#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>

int main(void)
int fd;
unsigned char data;

printf("Disabling WiFi whitelist check.\n");
fd = open("/dev/nvram", O_RDWR);
lseek(fd, 0x6a, SEEK_SET);
read(fd, &data, 1);
printf("CMOS address 0x6a: %02x->", data);
data &= ~0x80;
printf("%02x\n", data);
lseek(fd, 0x6a, SEEK_SET);
write(fd, &data, 1);


I've tried it on my ThinkPad X31, but it doesn't work at all. The CMOS
has a value 0xfa at the offset 0x6a, so the most upper bit is already

Vojtech Pavlik
SuSE Labs, SuSE CR
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