a) How is an application-layer gateway (ALG) different from a firewall?
Application layer.
Gateway
A hub doesn't function as a gateway, the easiest way to get a gateway is to use something like a Linksys or Netgear router, they will function as the gateway as well as add another layer of security between your network and the outside world.
The Application Layer Gateway Service is a part of Microsoft Windows that provides support for third-party plugins. This allows the network protocols to pass through the firewall and contributes to internet connectivity sharing.
Gateway network device
data link layer
Destination MAC: 0030.8517.44C4 Default gateway: 172.16.1.1
Gateways work on all seven OSI layers . The main job of a gateway is to convert protocols among communications networks.
a gateway can translate information between different networks data formats or network architecture. most gateways operate at the application layer. it can also be operated on network or session layer. by: talha jamal and farhan moin (kinpoe)
That is a loaded question...it depends on what you mean by gateway. I proxy server can be a gateway so can a router. Typically, its gateway=router. check this chart out: http://www.geocities.com/SiliconValley/Monitor/3131/ne/osimodel.html I consider it on the Network layer. Let me know if this helps! Thanks, Eric Elliston President of Elliston Consulting http://www.ellistonconsulting.com
Network Layer