Re: [LCtalk] Problems with TCP/IP Connectivity

[Fokko van Duin]

At 11:30 +0200 23-04-2006, Eric Christensen wrote:
> So to me it looks like I connect, provide provide a password that is 
> accepted, on a info request the box returns it's id and version, the 
> 65 is a switch to 16 bit mode

Is also used for keep alive. With LCedit+ there is always traffic, 
but with a custom application you can use the 65 once a minute to 
keep TCP connection open.



> and 0B is EngineGetGlobalData. And it is there that it goes wrong 
> (my opinion), the box seems to halt any connection over the tcp/ip 
> link because a ping from a different station shows that the ping 
> suddenly dies.

With LCedit+ you can run forever without any problems, there no real 
issues in the v2.05 stack, but..

1. The box can handle max 4 TCP connections, so if a custom 
application does not close the connection after use, you are running 
out of sockets.

2. You can kill the TCP stack of v2.05 when sending large pings, 
large fragmented UDP packets, and with XMAS and SYN attacks. So if 
the box is connected to the Internet without a firewall, robots will 
find it, and kill the stack (to find exploits).

The new firmware/stack v2.06 can survive much better those attacks, 
our demo box could not be killed anymore (no firwall, running v2.06) 
:-)

See: http://www.lanbox.com/support/Talk-Archive/msg-02120.html



> I have to recoonect under USB, reboot the box and then I can do all 
> this again, but same result each time.

Is someone sending large (more then 1460 bytes; fragmented) UDP 
packets to the box?


--
Fokko van Duin,
CDS advanced technology bv,
http://www.lanbox.com/