Serial over Ethernet module selection

[Charlie]

I'm a little confused (as usual). Not that I want to challenge your assertion, Dave, but my experience is that port 80 is often the *only* port open, since pretty much all HTTP browsing goes through it. Then 443 (HTTPS), then the email ones, then FTP and so on. But if I had to design something with a fixed port, it would be 80 because it's basically universally open. Just curious - what classification of customers block port 80? (schools, government, slave labor camps?)

[mackrackit]

Charlie,

I will guess you are behind a router at you home, if you are look at the settings. If you have not opened port 80 or any other port for that matter, they should all be closed. There is an exception with some manufactures that mistakenly left a port or two open causing a security risk.

So

When you make a request to a sever on a port, 80 or any other, the packets are addressed so the server knows where to send the requested packets back to. Your router will do something called NAT traversal to allow the traffic back through to the correct machine.

Lets say you set up a sever behind your router / firewall and you want it to receive request from the outside world, you will have to configure your router / firewall to pass that traffic through to the correct machine. Or place the home sever in the router's DMZ, but that is risky as far as security goes.

Most companies with any IT department worth anything will have every port closed to request from the outside. The one exception we commonly see is the use of a VPN tunnel.

[xapmanis]

Hey Dave,

The thing is that i want to use the pic as a server from withing a company with strict rules. And i want to sent some data from withing to the outside world via their Ethernet. Isn't this possible via port 80 ?? I wont request data from the outside and i wont sent data from the outside to the pic either basically i don't care about incoming data so let them be blocked.

Am i going to have problem again with port 80 and the router's firewall ??

[mackrackit]

You should be ok if communications to the device are from within the LAN. It will be able to send data out as any other device.

I just brought the port 80 thing up as sometimes we will put a server on say port 8347 and open that up through the fire wall. Sometimes port 80 is already being used or the idea of security by obscurity...
The Connect One devices will not allow this.

[Charlie]

Dave, I have a pretty good understanding of how routers work. If you want to get to any device from the internet, it needs to be at a publicly routable static address, regardless of the port number. It can not be hidden behind a NAT segment.
When someone wants to reach that server, however, the router THEY are behind will block OUTGOING requests on ports not specifically opened. Since the vast majority of those requests are on port 80, it's almost universally open. If you put your server on another port, it may be difficult to reach from many locations, unless you create a specific application and use UPNP or something.
I suppose what you are doing is having the fixed IP source router route a specific port request to a specific internal address and port - clever idea. But if you are doing this, and no other server is hosting anything on this address, why isn't port 80 as good as any other? Or are hosting companies blocking this to prevent people hosting from their homes?
I really am just curious - most of the things I do in this space are on private networks, and I'd be looking to serve internally only from this sort of device, with no need to access it from beyond the corporate firewall.

[xapmanis]

Thank you Dave and Charlie for your commends !! I'll try to buy a couple of nano socket module and start working as soon as possible !!!


Best regards, Kostas.

[mackrackit]

Dave, I have a pretty good understanding of how routers work. If you want to get to any device from the internet, it needs to be at a publicly routable static address, regardless of the port number. It can not be hidden behind a NAT segment.

Wrong, I have several servers behind NATs on different ports on different LANs.

When someone wants to reach that server, however, the router THEY are behind will block OUTGOING requests on ports not specifically opened. Since the vast majority of those requests are on port 80, it's almost universally open. If you put your server on another port, it may be difficult to reach from many locations, unless you create a specific application and use UPNP or something.

Wrong again. If the device is on a port other than 80 for http request all you have to do is add a ":" then the port number. abc.com:1234

I suppose what you are doing is having the fixed IP source router route a specific port request to a specific internal address and port - clever idea. But if you are doing this, and no other server is hosting anything on this address, why isn't port 80 as good as any other? Or are hosting companies blocking this to prevent people hosting from their homes?

Now you are getting it! Yes, a port is a port as far a working, it is more to do with security audits. And yes, some hosting companies block 25, 80, and others.

I really am just curious - most of the things I do in this space are on private networks, and I'd be looking to serve internally only from this sort of device, with no need to access it from beyond the corporate firewall.

Then you should not have any problems. Unless you are crossing different sub nets... but that is another story... Contact your IT department if that is the case.

[Charlie]

Wrong, I have several servers behind NATs on different ports on different LANs.
Wrong again. If the device is on a port other than 80 for http request all you have to do is add a ":" then the port number. abc.com:1234
Now you are getting it! Yes, a port is a port as far a working, it is more to do with security audits. And yes, some hosting companies block 25, 80, and others.
Then you should not have any problems. Unless you are crossing different sub nets... but that is another story... Contact your IT department if that is the case.

Dave, I think we've hijacked this thread enough. However, simply saying I'm wrong, then describing a situation different in detail from what I was stating, really isn't helping anyone understand. Routing and security is complex business - we can agree on that. There are many ways to skin a cat. I'm sure yours works for you as well as mine does for me. I was just trying to understand yours and maybe learn a new method. And I work in IT, so calling them (as you've told me twice) means calling myself or one of my colleagues.