Subject: From: Date:

Re: [ECS] Web access Don Stephens Thu, 29 Jun 2000 14:36:45 -0700

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Thanks Martin:

I assume if I pay for a static IP address, I do away with the NAT at the
ISP? Then I will have to deal with the router at my house....which I have
some control over. Is this correct?

Thanks:
Don


----- Original Message -----
From: "Martin Terry" <Martin.Terry@mail.tribnet.com>
To: <ecs-list@netbloc.com>
Sent: Thursday, June 29, 2000 2:29 PM
Subject: RE: [ECS] Web access


> I'm not Dario, but since this is my profession I'll take a stab at a brief
> explaination. :)
>
> First off, depending on how NAT is setup, you may not be able to connect
at
> all. On the routers we manage, NAT can be inbound (meaning someone is
asking
> to connect inward, for example a web server), outbound (meaning I'm
> initiating a connection outward, for example a web browser), or
> bi-directional (meaning both of the above are true).
>
> The advantages of outbound connections is that you can map multiple
outbound
> connections to a single address, in our company as an example all 800
> employees can be surfing the web and from the Internet's perspective they
> all appear to be coming from a single address. You couldn't tell them from
> 800 web windows on a single machine.
>
> The disadvantage is that you can't initiate an inbound connection - for
> example an employee cannot host a web site on his personal computer and
> allow people on the internet to connect - the router simple rejects these
> requests.
>
> So if your ISP doesn't allow you to host a web server, and has setup
> outbound NAT only, you are out of luck.
>
> If you have a bi-directional NAT mapping, basically it is simple a 1 to 1
> address translation. Anything that "appears" to come from one address is
> changed to another.
>
> How can you tell where to connect to ECS?
>
> This is a tough question, because the event and batch files I've seen with
> ECS rely on the workstation finding out it's own address and then mailing
> that address to the user. For NAT (Network Address Translation) this won't
> work, because the IP address of the workstation isn't the same as what it
> appears to be to the end user, on the other side of the router. It's not
> taking the conversion into account (it can't). Here's an example:
>
> Workstation ( IP 192.168.1.1 ) Internal network address often used with
NAT.
> with web server (ECS for example)
>        |
>        |
>        | Network 192.168.1.x
>        |
>        |
> Router (IP 192.168.1.2) with NAT entry for workstation 192.168.1.3 <->
> 207.46.131.30
>        |   (IP 207.46.131.1)
>        |
>        | Network 207.46.131.x
>        |
>        |
>  Internet "cloud"
>        |
>        |
>        |
> End user with browser (IP 192.18.97.195)
>
> to contact ECS the browser would have to enter http://207.46.131.30:3000
in
> order to make the connection. This request eventually translates to a
> request to the router, which is masquerading as 207.46.131.30, and usually
a
> bunch of other addresses. The router has a table that says "if you get a
> request for 207.46.131.30, change it to 192.168.1.1". It then passes the
> data on, and it appears to come from the address 192.168.1.3.
>
> NAT can be a real problem (read not work) when the machines communicating
> pass their IP addresses in the data stream. NAT cannot see this and modify
> it appropriately, therefore several protocols will not work via NAT.
>
>
>
>
> -----Original Message-----
> From: Don [mailto:donstephens@101freeway.net]
> Sent: Thursday, June 29, 2000 9:19 AM
> To: ecs-list@netbloc.com
> Subject: Re: [ECS] Web access
>
>
> Hi Dario:
>
> Since you seem to know something about how this works, I'll ask you. I
have
> a router on my local lan that uses NAT for addressing, and I have a
dynamic
> address at my ISP, although I have a DSL line and it has never changed.
I'm
> want to access ECS from a remote computer. How do I come up with an URL
for
> ECS?
>
> Thanks:
> Don
> ----- Original Message -----
> From: "Dario" <adpm.to@inwind.it>
> To: <ecs-list@netbloc.com>
> Sent: Thursday, June 29, 2000 7:31 AM
> Subject: Re: [ECS] Web access
>
>
> > Mark Gilmore ha scritto:
> > >
> > > Note that if another port # would be more conventional, I
> > > could easily change the default to something other than
> > 3000.
> >
> > As there's not yet a standard for home automation access via
> > WEB, I
> > guess everything is OK (IMHO)
> > Actually, if ECS is working wuite like a WEB-server, then you
> > could use
> > port 80, the standard for HTTP (so nobody would have trouble).
> > Of
> > course, provided you're not using other webservers on ECS
> > machine.
> > I've set up port 80 on my system, and I can get to it via any
> > computer.
> >
> > Dario
> >

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