Hardware gateways

• Market: they are in the upswing, see this article.

  • Cisco: product line and some problems.
  • WatchGuard: product line.
  • SonicWall: product line.
  • D-Link: product line (a low cost SOHO player).

• How they work: D-Link example.

  • Filtering inbound traffic: allowing special applications, redirecting traffic to specific servers, denying all other inbound traffic.
  • Filtering outbound traffic: allowing/denying specific LAN hosts to use certain ports.
  • NAT and DHCP: all LAN hosts use local IP numbers, only the gateway has both a local IP number and a regular Internet IP number.
    • NAT - network address translation - converts the request of a host in the LAN to the gateway IP number when sending an outbound request, and convert back to the local IP number when receiving an inbound reply.
    • DHCP: automatically assigns local IP numbers, DNS, etc., to hosts in the LAN, as shown in this example (disabled).

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