socket problem?

[Steve Holden]

Zajcev Evgeny wrote:
> 
> actually I'm intented in creation not in destruction
> but I need understand TCP, UDP over IP in lowerest level
> whithout understanding,  network programming became
> waste spending time IMHO.
> I chose python for learning protcols becouse of it is greate programming
> language :)
> 
You can develop understanding without programming the complete TCP
transport layer over again!

> by the way one of application of sending random tcp packets over sock_raw is
> some printers have telnet service and have no authentification
> so if any user telnet on it he have administrator privileges
> the solution of this problem:
>  your PC in the same sub-net with who want to telnet to printer
>  sniifing net, and when there any SYN packet to printer:23
>  send to printer RST packet from villain address (ACK and souce port is knowing from sniffing)so he even cant estableash connect.
> 
This seems pretty extreme, but does at least explain why you might want to
simulate a TCP reset using a raw socket.  However, have you checked that the
IP layer in the printer will respond as you want?  It all depends on how
it uses the ARP cache, since some IP implementations won't accept packets
from the same IP address and different MAc addresses.  One of the reasons
is to avoid accepting the spoofed packets you are intending to raise!

Wouldn't it be simpler to impose some sort of filtering at the printer, or
simplt to turn the telnet service off?

regards
 Steve
> thanks for helping.
> 
> --
> zev

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