Программу нужно запускать с ключом т.е. указать свое имя каким оно будет в сети, когда вы будете обмениваться сообщениями.

Например: Message.exe/ sergei

Текст программы:

typedef struct
{
unsigned char netadd[4];
unsigned char nodeadd[6];
unsigned short socket;
} IPXADDRESS;

typedef struct
{
unsigned short checksum;
unsigned short length;
unsigned char tc;
unsigned char type;
IPXADDRESS dest;
IPXADDRESS source;
} IPXHEADER;

typedef struct
{
void far *linkaddress;
void (far *esraddress)();
unsigned char inuse;
unsigned char cc;
unsigned short socket;
unsigned char workspace[16];
unsigned char immedaddr[6];
unsigned short fragcount;
void far *fragaddr1;
unsigned short fragsize1;
void far *fragaddr2;
unsigned short fragsize2;
} IPXECB;

#ifdef __cplusplus
extern "C" {
#endif

extern unsigned short reverseword ( unsigned short );
extern unsigned long ipxinit ( void );
extern unsigned long ipxentry;
extern void ipxgetaddress ( void * );

extern unsigned short ipxgetmaxpacketsize ( void );
extern unsigned short ipxgetretrycount ( void );
extern unsigned short ipxverifychecksum( IPXECB * );
extern unsigned char ipxopensocket ( unsigned char, unsigned short * );
extern void ipxclosesocket ( unsigned short );
extern unsigned char ipxlistenforpacket ( IPXECB * );
extern void ipxsendpacket ( IPXECB * );
extern void sendwithchecksum( IPXECB * );
extern void ipxrelenquishcontrol ( void );
#ifdef __cplusplus
}
#endif

ассемблер:

.model large
.data
public _ipxentry
_ipxentry dd 0

.code

public _reverseword
_reverseword:
push bp
mov bp,sp
mov ax,[bp+6]
xchg ah,al
pop bp
retf

public _ipxinit
_ipxinit:
push di
push es
mov ax,7A00h
int 2Fh
cmp al,0FFh
jnz _ipxinit0
mov word ptr [_ipxentry+0],di
mov word ptr [_ipxentry+2],es
_ipxinit0:
mov dx,word ptr [_ipxentry+2]
mov ax,word ptr [_ipxentry+0]
pop es
pop di
retf

public _ipxgetaddress
_ipxgetaddress:
push bp
mov bp,sp
mov bx,0009h
mov si,[bp+6]
mov es,[bp+8]
call [_ipxentry]
pop bp
retf

public _ipxgetmaxpacketsize
_ipxgetmaxpacketsize:
mov bx,001Ah ;0d
call [_ipxentry]
retf

public _ipxgetretrycount
_ipxgetretrycount:
mov bx,001Ah
call [_ipxentry]
mov ax,cx
retf

public _ipxopensocket
_ipxopensocket:
push bp
mov bp,sp
push ds
mov al,[bp+6]
mov bx,[bp+8]
mov ds,[bp+10]
mov dx,[bx]
pop ds
mov bx,0000h
call [_ipxentry]
push ds
mov bx,[bp+8]
mov ds,[bp+10]
mov [bx],dx
mov ah,00h
pop ds
pop bp
retf

public _ipxclosesocket
_ipxclosesocket:
push bp
mov bp,sp
mov bx,0001h
mov dx,[bp+6]
call [_ipxentry]
pop bp
retf

public _ipxlistenforpacket
_ipxlistenforpacket:
push bp
mov bp,sp
push ds
push di
push si
push es
mov bx,0004h
mov si,[bp+6]
mov es,[bp+8]
call [_ipxentry]
mov ah,00h
pop es
pop si
pop di
pop ds
pop bp
retf

public _ipxsendpacket
_ipxsendpacket:
push bp
mov bp,sp
push si
push es
mov bx,0003h
mov si,[bp+6]
mov es,[bp+8]
call [_ipxentry]
pop es
pop si
pop bp
retf

public _sendwithchecksum
_sendwithchecksum:
push bp
mov bp,sp
push si
push es
mov bx,0020h
mov si,[bp+6]
mov es,[bp+8]
call [_ipxentry]
pop es
pop si
pop bp
retf

public _ipxrelenquishcontrol
_ipxrelenquishcontrol:
mov bx,000Ah
call [_ipxentry]
retf

public _ipxverifychecksum
_ipxverifychecksum:
push bp
mov bp,sp
push si
push es
mov bx,0022h
mov si,[bp+6]
mov es,[bp+8]
call [_ipxentry]
pop es
pop si
pop bp
retf

end

С++

#include <stdio.h>
#include <bios.h>
#include <fcntl.h>
#include <dos.h>
#include <time.h>
#include <io.h>
#include <stdlib.h>
#include <conio.h>
#include <string.h>
#include <mem.h>
#include "ipx.h"

int getkey(void);
void sent_buf(int msh,char *sbuffer);

unsigned int socket=0x5000;
#define NPACKETS 5 // количество окон приема/прослушивания
#define PACKETSIZE 200 // размер буфера сообщения

IPXECB recb[NPACKETS],secb[NPACKETS];
IPXHEADER rheader[NPACKETS],sheader[NPACKETS];
unsigned char rbuffer[NPACKETS][PACKETSIZE];
unsigned char sbuffer[NPACKETS][PACKETSIZE];
unsigned char M_ADDR[6];
char NAME_USER[30];
//------------------------------------------------------------------------------
void main ( int argc, char *argv[] )
{
char buf[100],mes[150];
unsigned short ra;
int Flag_exit,key,i;
IPXADDRESS myaddress;

clrscr();
if(argc<2)
{
printf("Ошибка задания параметров !\n\n");
printf("message.exe NAME_USER \n");
exit(1);
}
strcpy(NAME_USER,argv[1]);

if(!ipxinit()) { printf("IPX не найден !\n"); exit(1); }

if (ipxopensocket(0x00,&socket) == 0xff) { printf("Канал уже открыт !\n"); exit(1); }

printf("F1 - ввести сообщение. Esc - выход.\n\n\n");
ipxgetaddress(&myaddress);
for(i=0;i<6;i++) M_ADDR[i]=myaddress.nodeadd[i];

// инициализируем окна прослушивания
for(ra=0;ra<NPACKETS;ra++)
{
recb[ra].socket=socket;
recb[ra].esraddress=NULL;
recb[ra].fragcount=2;
recb[ra].fragaddr1=&rheader[ra];
recb[ra].fragsize1=sizeof(IPXHEADER);
recb[ra].fragaddr2=&rbuffer[ra];
recb[ra].fragsize2=PACKETSIZE;
ipxlistenforpacket(&recb[ra]);
}

Flag_exit=0;
while(!Flag_exit)
{
if( kbhit() ) // нажата клавиша
{
key=getkey();
switch(key)
{
case 27: // Esc
Flag_exit=1;
break;
case 315: // F1
textcolor(7);
printf("-> ");gets(buf); printf("\n");
sprintf(mes,"%s: %s",NAME_USER,buf);
for(ra=0;ra<NPACKETS;ra++)
{
if(!secb[ra].inuse )
{ sent_buf(ra,mes); break; }
}
break;
}
}

for(ra=0;ra<NPACKETS;ra++)
{
if(!recb[ra].inuse) // приемные окна
{
if(memcmp(rheader[ra].source.nodeadd,M_ADDR,6))
{
textcolor(3);
cprintf("%s\n\r",rbuffer[ra]);
}
memset(rbuffer[ra],0,PACKETSIZE);
recb[ra].socket=socket;
recb[ra].esraddress=NULL;
recb[ra].fragcount=2;
recb[ra].fragaddr1=&rheader[ra];
recb[ra].fragsize1=sizeof(IPXHEADER);
recb[ra].fragaddr2=&rbuffer[ra];
recb[ra].fragsize2=PACKETSIZE;
ipxlistenforpacket(&recb[ra]);
}//if(!recb[ra].inuse)
}//for(<NPACKETS)

}

ipxclosesocket(socket);
}

//----------------------------------
void sent_buf(int msh,char *buf)
{
int i;

memset(sbuffer[msh],0,PACKETSIZE);
sprintf(sbuffer[msh],"%s",buf);

for(i=0;i<6;i++) sheader[msh].source.nodeadd[i]=M_ADDR[i];
for(i=0;i<4;i++) sheader[msh].source.netadd[i]=0x9;

for(i=0;i<4;i++) sheader[msh].dest.netadd[i]=0x09;
for(i=0;i<6;i++) sheader[msh].dest.nodeadd[i]=0xff;//M_ADDR[i];
for(i=0;i<6;i++) secb[msh].immedaddr[i]=0xff;//M_ADDR[i];
sheader[msh].dest.socket=socket;
sheader[msh].type=4;
secb[msh].socket=socket;
secb[msh].esraddress=NULL;
secb[msh].fragcount=2;
secb[msh].fragaddr1=&sheader[msh];
secb[msh].fragsize1=sizeof(IPXHEADER);
secb[msh].fragaddr2=&sbuffer[msh];
secb[msh].fragsize2=PACKETSIZE;
ipxsendpacket(&secb[msh]);
}

//-----------------------------------------------------------
int getkey(void)
{
int key, lo, hi;

key = bioskey(0);
lo = key & 0X00FF;
hi = (key & 0XFF00) >> 8;
return(lo ? lo : hi + 256);
}

Программа проверена и работает нориально.