Receiving data with Sockets when behind a Router

[Jim Ault]

The basic idea of a LAN behind a router is that the router assigns IP
addresses dynamically therefore each cpu can have a different IP address
every time it is booted.  Inexpensive routers can only forward one port to
one LAN IP address (internal network)  thus

<using 9454 as the port number, for example>

1  set a cpu firewall open for 2-way traffic on port 9454
2  set the router to forward incoming packets from the outside world on port
9454 to cpu at IP address 192.168.1.201 (this is a fixed setting by the
admin)
3  cpu at (201) address is running an app that tells the operating system to
open port 9454 on the cpu, then the app sends and receives on port 9454, and
at some point could close the port.

Rebooting the router or the computer can change the cpu's assigned address
of (201), thus forwarding is thwarted.  Network printers have to have their
router-assigned IP address fixed when installed, or they may not be
reachable.

Rebooting the router will not change the port forwarding.
Resetting the router will indeed clear the port forwarding.
The broadcasting source specifies a port number and the user must match that
port.
The broadcasting source specifies a computer address (IP address) which is
usually the static address of the router.  In the case of DSL service, I
believe each user is assigned a static IP address to make that system work.

This is based on my experience and may not be entirely correct.  This should
be accurate for most home or small office systems.

Hope this helps.

Jim Ault
Las Vegas


On 2/2/07 11:35 AM, "Neal Campbell K3NC" <nealk3nc at gmail.com> wrote:

> Could it be as simple as your router does not have the right
> configuration to forward the port to your computer (or you have a
> firewall that prevents it since it thinks its from a non-trusted
> network?
> 
> Neal Campbell K3NC
> nealk3nc at gmail.com
> 
> 
> "Devoted to Dogs: How to be your dog's best owner"
> Great Dog Book  at www.abrohamneal.com
> 
> 
> 
> On Feb 2, 2007, at 12:33 AM, Derek Bump wrote:
> 
>> I'm in need of some guidance.  How do you resolve an IP address
>> when it's behind a router or a firewall?
>> 
>> I'm trying to build a simple communications device in Revolution,
>> and I have been looking at some of the demo stacks that are out
>> there.  They all work wonderfully, but I occasionally run into the
>> problem of being behind a Wireless Router.
>> 
>> My IP address when connected through the router is 192.168.0.7,
>> while the outside world see my IP as 69.179.91.117.  Attempting to
>> connect to the public IP address results in nothing.
>> 
>> I mean I'm figuring with all the Instant Messengers and P2P
>> programs out there that there's a way to do this.  Help!
>> 
>> 
>> Derek Bump
>> Dreamscape Software
>> http://www.dreamscapesoftware.com/
>> 
>> _______________________________________________
>> use-revolution mailing list
>> use-revolution at lists.runrev.com
>> Please visit this url to subscribe, unsubscribe and manage your
>> subscription preferences:
>> http://lists.runrev.com/mailman/listinfo/use-revolution
> 
> _______________________________________________
> use-revolution mailing list
> use-revolution at lists.runrev.com
> Please visit this url to subscribe, unsubscribe and manage your subscription
> preferences:
> http://lists.runrev.com/mailman/listinfo/use-revolution