Want this question answered?
a) How is an application-layer gateway (ALG) different from a firewall?
Application gateway/proxy
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.
of course , You can use gateway or firewall for intranet. Intranet is a combination of multiple local area networks. In Huge organizations, intranets are prevented from unauthorized external access by using network gateway and firewall. For small organizations, intranets may be created simply by using private Internet Protocol address ranges.
Turn on the feature, if available on your computer's OS and your network router/gateway/firewall. :) Google (search) "UpNP" along with your OS and then again with your router/gateway.
Great firewall software would include zonealarm or webroot. Even the windows firewall included with Windows XP SP2 and beyond should do the trick. And remember that if you have a router it also has a hardware firewall in it.
A firewall can be either hardware or software
Firewall act as a security gateway between two networks as trusted and untrusted networks. (VIKRAM SINGH)
Is the Windows Firewall enabled, or any other Firewall installed and not configured?
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.
Check your local system's firewall for blocking of ICMP (ping) traffic.
circuit-level gateway