2 replies to this topic

[seascan]

Hi.  I've got a strange problem and after a few days of struggling and searching I'm throwing it out to the community:

 

I set up a webserver on my Netduino Plus 1.  I connected it to my local network.  Finally, I set port fowarding on my home router to point to it.  Everything worked great for 10 minutes or so.  Then the ND would lock up.  Usually I could not even cycle it with the reset button. Seriously locked up.  It didn't appear to lock up while I was debugging -- just when it was stand-alone.

 

So, I eventually quit doing the port forwarding and only am operating from my local network.  So far things look great.  It's been stable for an hour or so which is a lot more that what I was getting for the past two days.

 

Any ideas why port forwarding and accessing my ND from the internet would cause a lock up??  If this stays stable for a day or two then my next step will be setting the external port to something weird (12345 or something) instead of port 80.

 

Thanks for any insights.

 

Terry

[wendo]

My guess would be you're seeing a lot of port scanning going on searching for vulnerable web servers to hack. Either your webserver gets incorrectly identified as vulnerable and they throw a whole lot of random data at it trying to cause a buffer overflow, which causes some issue on your netduino (likely some resource or buffer exhaustion), or there are simply a lot of requests hitting it in a short time causing the same thing (think 10's or 100's per second).

 

The internet is _very_ hostile to web servers. If you want it open to the internet, I would suggest either putting it on another port which may help, but likely will still bring about the same result, if somewhat slower. Or use a VPN or some other proxy system to protect the netduino. 

 

Depending on the hardware you have available you could setup apache/nginx as a proxy forwarder for the netduino, that way the hostile traffic would be handled by full software and your netduino's webserver would be available from a folder, for example

 

http://www.example.com/netduino

 

only with the /netduino on the end does traffic actually make it to your netduino. On top of that you can protect that folder in apache/nginx to require a username and password.

[seascan]

Thanks, Wendo.  That makes sense.

 

I tried changing the port and the ND has been stable for 2 hours.  So far, so good.