help with Arduino TCP/IP connect problem

[Shinoj VG]

Hi,

When the connection fails, please do a netstat -an | grep 8000 and report back on the status of connection as seen from linode end. Is there something similar you can do to find the connection status on Arduino? If yes, this will be helpful in debugging. My guess at this point is that this is something to do with the client side rather than the server.

Regards,
Shinoj.

> From: icanprogram-sKcZck+fQKg at public.gmane.org
> To: tlug-lxSQFCZeNF4 at public.gmane.org
> Subject: Re: [TLUG]: help with Arduino TCP/IP connect problem
> Date: Wed, 27 Jun 2012 14:42:31 -0400
> 
> Great suggestion.    I've managed to get this done now.   The results are 
> posted at:
> 
> http://www.icanprogram.com/opndrs/arduino/connectproblem.html
> 
> We ran 3 tests all from same network node:
> 
> i) Arduino -> Linode:8000
> ii) Arduino -> Linode:80 (exactly same code as i) with only port number 
> switched)
> iii) Linux stub -> Linode:8000
> 
> In all cases the packet sequence and timing seems to be virtually identical.
> 
> The Linux stub test always succeeds.   The Arduino -> Linode:80 always 
> succeeds.    The Arduino->Linode:8000 almost never succeeds and appears to 
> timeout in two distinct ways:
> 
> a) no TCP/IP packets make their way to the Linode at all
> b) correct sequence of TCP/IP packets appears to be exchanged but Arduino 
> times out anyway
> 
> Any suggestions?
> 
> Thanks in advance.
> 
> bob
> 
> 
> 
> On Monday 25 June 2012 05:49 am, Shinoj VG wrote:
> > Try doing a packet capture using tcpdump on linode and see if you notice
> > any difference between the handshake happening for port80 and custom server
> > when you try to connect from arduino.
> >
> > Regards,
> > Shinoj.
> >
> > > From: icanprogram-sKcZck+fQKg at public.gmane.org
> > > To: tlug-lxSQFCZeNF4 at public.gmane.org
> > > Subject: [TLUG]: help with Arduino TCP/IP connect problem
> > > Date: Thu, 21 Jun 2012 13:04:57 -0400
> > >
> > > We are having a lot of problems debugging a TCP/IP connect problem
> > > between my associate's Arduino and my Linode server app.    The gist of
> > > the problem is described here:
> > >
> > > http://www.icanprogram.com/opndrs/arduino
> > >
> > > It would appear that the chip used to handle the TCP/IP stack on the
> > > Arduino thinks that the socket connection it establishes (as a client)
> > > has not succeeded and it times out.    However, on the Linode side we
> > > observe that the socket connection has succeeded (ie. been accepted)
> > > because we get our child process spawned.   Furthermore if we use the
> > > Linux C client we never observe a client socket timeout from my
> > > associates node.
> > >
> > > The server code is listed in the link above, and uses a traditional
> > > accept connection -> fork child handler approach.   The child process
> > > immediately closes the duplicated parent listener socket.   The parent
> > > process immediately closes the duplicated accepted socket file
> > > descriptor.
> > >
> > > From my travels in Google land it appears that there is a 3 way hand
> > > shake involving SYN and ACK TCP/IP packets which are exchanged to
> > > consumate a socket connection.    I'm guessing these are the messages
> > > that the Arduino Wiznet w5100 chip is missing.   I certainly don't know
> > > how to control this level from my high level C library.
> > >
> > > Interestingly if the Arduino is instructed to connect to the port 80 on
> > > my Linode it succeeds in that connect almost 100% of the time whereas the
> > > connections to my custom server fails more than 90% of the time.
> > >
> > > I'd love to hear some thoughts on how we might go about debugging this
> > > problem.    If you know of any Arduino developers out there,  we'd love
> > > to have more eyeballs on this problem.
> > >
> > > Thanks in advance for your help.
> > >
> > > bob
> > > --
> > > The Toronto Linux Users Group.      Meetings: http://gtalug.org/
> > > TLUG requests: Linux topics, No HTML, wrap text below 80 columns
> > > How to UNSUBSCRIBE: http://gtalug.org/wiki/Mailing_lists
> --
> The Toronto Linux Users Group.      Meetings: http://gtalug.org/
> TLUG requests: Linux topics, No HTML, wrap text below 80 columns
> How to UNSUBSCRIBE: http://gtalug.org/wiki/Mailing_lists
 		 	   		  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://gtalug.org/pipermail/legacy/attachments/20120628/af98797c/attachment.html>