Jaime, thank yor for help. I tried to use your code and produces the following program. This program doesn't receive any data (receive buffer is empty):
an infinite loops occurs if calling receive command
and no error occurs. If I implement the same thing using MSWINSOCK, it works. Can you point me what is wrong with this code ?

** form.init method
ACTIVATE SCREEN
CLEAR
ON SHUTDOWN QUIT
SET TALK OFF
SET ECHO OFF

with ThisForm
   .OleControl1.LocalAddress = "194.106.108.233" &&& your ip
   .OleControl1.LocalPort = 0
   .OleControl1.Create()
    .OleControl1.RemoteNameAddrXlate = .T.
    .OleControl1.RemoteName = "pepe.online.ee"
   .OleControl1.RemotePort = 7
   .OleControl1.Blocking = .F.
   .OleControl1.ConnectTimeout = 5
   .OleControl1.object.Connect()
endwith

DO WHILE THIS.olecontrol1.state!=4
  IF INKEY(0.5)=27
    RETURN .F.
    ENDIF
  ? 'Connecting', THIS.olecontrol1.lasterrorstring
  ENDDO

cBuffer = REPLICATE( CHR(0), 100 )

DO WHILE INKEY(.5)!=27 and THIS.olecontrol1.state=4
  THIS.olecontrol1.send( CREATEBINARY(m.cBuffer) )
  CStr = ''
  * ??????????????????????????????????????????????????
  * The following loop will run infinitely. Why ?
  DO WHILE INKEY(.5)!=27 and THIS.olecontrol1.state=4 AND EMPTY(cStr)
    THIS.olecontrol1.receive(1)
    cStr = this.olecontrol1.receivebuffer
    ? THIS.olecontrol1.lasterrorstring
    ENDDO
    
  ?'Received', len(cStr), cStr
  IF cStr!=m.cBuffer
     ?? 'Error'
   ELSE
    ?? 'OK'
    ENDIF      
  ENDDO
RETURN .F.

>Your code doesn't seem to connect the right way. If your Socket/X control's name is olecontrol1, your should start by doing something like this to connec:
>

>with ThisForm
>   .OleControl1.LocalAddress = "192.168.1.1" &&& your ip
>   .OleControl1.LocalPort = 0
>   .OleControl1.Create()
>   *** if you connect by ip address, you should do then
>    .OleControl1.RemoteNameAddrXlate = .F.
>    .OleControl1.RemoteAddress = "212.155.99.148"  &&& other side's ip
>   *** otherwise if you connect by name
>    .OleControl1.RemoteNameAddrXlate = .T.
>    .OleControl1.RemoteName = "www.eetasoft.ee"
>
>   .OleControl1.RemotePort = 7
>   .OleControl1.Blocking = .F.
>   *** now set a connection timeout, let's say 5 seconds
>   .OleControl1.ConnectTimeout = 5
>
>   *** finally connect...
>   .OleControl1.object.Connect()
>endwith
>

>Now, if you check ThisForm.OleControl1.State, it should really be 4 and then you can go on with the data transmissions.
>
>Cheers,
>Jaime
>
>>I need to send and receive 00 bytes from tcp port.
>>I have found that ms winsock control corrupts tcp packets containing 00
>>bytes.
>>
>>So I desided to use Mabry Socket/X control.
>>
>>I made a simple test program. This program sends TCP packets to port 7
>>and receives data from this port.
>>
>>I dropped Socket/X control to vfp 5 form and added the following code
>>to form init :
>>
>>ACTIVATE SCREEN
>>CLEAR
>>ON SHUTDOWN QUIT
>>THIS.olecontrol1.CREATE()
>>DO WHILE THIS.olecontrol1.state!=3
>> IF INKEY()=27
>> RETURN .F.
>> ENDIF
>> ? THIS.olecontrol1.lasterrorstring, THIS.olecontrol1.state
>> ENDDO
>>
>>THIS.olecontrol1.CONNECT( 'www.eetasoft.ee', 7 )
>>
>>DO WHILE THIS.olecontrol1.state!=4
>> IF INKEY()=27
>> RETURN .F.
>> ENDIF
>> ? THIS.olecontrol1.lasterrorstring, THIS.olecontrol1.state
>> ENDDO
>>
>>cBuffer = REPLICATE( CHR(0), 100 )
>>
>>DO WHILE INKEY()!=27
>> THIS.olecontrol1.sendto('www.eetasoft.ee', 7, m.cBuffer )
>> THIS.olecontrol1.receivefrom('www.eetasoft.ee', 7 )
>> ? THIS.olecontrol1.lasterrorstring, THIS.olecontrol1.state
>> IF LEN(THIS.olecontrol1.receivebuffer)!=100 or ;
>> THIS.olecontrol1.receivebuffer!=m.cBuffer
>> ?? 'Error'
>> ELSE
>> ?? 'OK'
>> ENDIF
>> ENDDO
>>
>>RETURN .F.
>>
>>
>>However, this code does not cause any internet access at all.
>>.State after .create() remains 3
>>
>>Is it possible to use Mabry Socket/X with VFP ?