QUESTION ABOUT GATEWAYS

mgmguy1 · December 2005

Team,
At the moment i am Lising to my Network + Series CBT Nugget and I am on Part 2 of the Networking hardware sections and the guy is talking about gateways I am have a question.

Gateway is a blanket term for any hardware or software that joins two dissimilar networks. A Gateway also exists on the borders of a network,which means they are functionally related to firewalls. Givin this information I have a question.

If an ISP uses a gateway to provide internet services to the masses as well as uses the gateway as a Firewall to restrict access to there mainframe. Why are there software and hardware firewalls at all if gateways can be configured to restrict access?

I know I am missing something here.
Please help clear this one up for me.

MGMGUY1

keatron · December 2005

Typcially a gateway is just what it says, a gateway into or out of something (in this case a network, subnet, or wan). Then comes the question of whether or not the gateway has any type of access control in place. This is where a firewall or similar devices would come in. So in simple terms, you could say, A gateway can be secured by a firewall from a theoretical perspective. People in the industry do sometimes incorrectly refer to a firewall as a gateway. Again if you look at the physical side. If a gate is open, or if it has no lock or gaurd posted on it, then it is not secured or have any access control. For IT sake, a gateway is usually referencing a router or similar physical or logical technology.

If you're sitting behind an internal network with a private address space of 10.10.10.0, and your isp dns servers sit at 64.58.19.12, then how do you communicate with it? A router right, and often referred to as a gateway. So all the hosts on that private subnet would point to the router as a the gateway out (or some firewall mechanism which would then point to the router or pass traffic through to the router).

The longer you're in this field, the more you'll find the same terms used to describe different things, but for now it sounds like you should stick to the basic definitions.

Webmaster · December 2005

If an ISP uses a gateway to provide internet services to the masses as well as uses the gateway as a Firewall to restrict access to there mainframe. Why are there software and hardware firewalls at all if gateways can be configured to restrict access?

I'm not sure I understand this question, or how you came to the question based on the first sentence, but I think you are overthinking it. The gateway is basically a function, and as many network functions it can be implemented in hardware (such as routers, firewalls, and dedicated hardware appliances), or software (i.e. a proxy server that allows IPX clients to access an TCP/IP network such as the Internet).

From my TechNotes:
"A gateway is a hardware device or a computer running software that allows communication between networks with dissimilar network protocols or architectures."

The classic example of the definition of a gateway is a device (which can be a linux box running software) that allows a connection and translation between Ethernet and an IBM SNA mainframe environment. A gateway, especially for the Network+ exam, is something that allows you to connect two networks that would normally not be able to communicate with eachother because they speak a different language. Which is usually not something an ISP uses. Although a router, as well as a firewall(which is basically an advanced router), can be a 'default gateway' for TCP/IP clients, it's usually not the same type of classic gateway, even though one side of the router can be ATM and the other Ethernet for example, it routes between networks with the same protocol, i.e. IP to IP.

mgmguy1 · December 2005

Thank you. I have some good materials I am studying with but what the guy says in the CBT and what I have on Paper differ a-little bit.
Again Thanks for the Feedback

x_Danny_x · December 2005

say, the ip address given to the gateway is the first ip address of the network?

I thought for sure that the gateway ip address would be network address of the network.

keatron · December 2005

If the gateway address is 10.10.10.1, then it is the first in that network, but the actual network address would be 10.10.10.0

QUESTION ABOUT GATEWAYS

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