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Posted by on May 28, 2007, 7:22 pm
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>
>
>Elmo P. Shagnasty wrote:
>> Warren H wrote:
>>
>>> What the hell is a "control device" or "controller"? Since their
>>> getting
>>> IP addresses, can we assume they're actually routers?
>>
>> he said "building control devices". I presume he meant
>> security-oriented pieces--door controllers, alarm controllers, HVAC
>> controllers, whatever.
>
>
>
>Hmm. Never thought of that.
>
>In that case, they're just another computer. Nothing more. No reason to
>distinguish them from any other computer using a proprietary operating
>system. Why bother confusing the issue by giving them a special name
>that has no significance in the world of networking?
Precisely.
>But that still doesn't materially change the answer. If they all have
>public IP addresses, the route between them still goes back to the CMTS
>or the DSLAM, and it they aren't properly submitted, they still won't be
>able to talk to each other. And they'll still be exposed to the public
>Internet for anyone to hack into.
>
>If they need to communicate with each other, the only practical way to
>do it is put them behind a single router, and give them private IP
>addresses. If you need to access them individually from the outside
>world, some kind of master control unit would also need to be on the LAN
>side of the router with them, and a VPN tunnel set-up to access it from
>the outside.
Many types of devices allow network control. This is typically done via
http. Most cable internet services do not permit you to run your *own*
servers. Devices with web control are, technically, servers. Also, the
cable and DSL services block port 80 and other well know server ports.
If the address is dynamically assigned, there needs to be some way to de-
termine that address from the outside. I'm no certain that it would be
easy to have multiple devices listening on the same port behind a router
unless the router can map one visible external port to the a particular
address on the inside network such as:
a.b.c.d:8080 -> 192.168.1.2:80
a.b.c.d:8081 -> 192.168.1.3:80
a.b.c.d:8082 -> 192.168.1.4:80
Can the typical Linksys-like router box do such?
--
VAXman- A Bored Certified VMS Kernel Mode Hacker VAXman(at)TMESIS(dot)COM
"Well my son, life is like a beanstalk, isn't it?"
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