Avaya Business Secure Router 222 Configuration - Basics Instrukcja Użytkownika Pobierz pdf (Strona 169)

100

101

Chapter 10 Firewalls 169

Nortel Business Secure Router 222 Configuration — Basics

Packet filtering vs. firewall

Below are some comparisons between the filtering and firewall functions of the

Business Secure Router.

Packet filtering:

• The router filters packets as they pass through the router’s interface according

to the filter rules you designed.

• Packet filtering is a powerful tool, yet can be complex to configure and

maintain, especially if you need a chain of rules to filter a service.

• Packet filtering only checks the header portion of an IP packet.

When to use filtering

1 To block or allow LAN packets by their MAC addresses.

2 To block or allow special IP packets that are neither TCP nor UDP, nor ICMP

packets.

3 To block or allow both inbound (WAN to LAN) and outbound (LAN to WAN)

traffic between the specific inside host or network A and outside host or

network B. If the filter blocks the traffic from A to B, it also blocks the traffic

from B to A. Filters cannot distinguish traffic originating from an inside host

or an outside host by IP address.

4 To block or allow IP trace route.

Firewall

• The firewall inspects packet contents as well as their source and destination

addresses. Firewalls of this type employ an inspection module, applicable to

all protocols, that understands data in the packet is intended for other layers,

from the network layer (IP headers) up to the application layer.

• The firewall performs stateful inspection. It takes into account the state of the

connections it handles, so that, for example, a legitimate incoming packet can

be matched with the outbound request for that packet and allowed in.

Conversely, an incoming packet masquerading as a response to a nonexistent

outbound request can be blocked.

1 2 ... 164 165 166 167 168 169 170 171 172 173 174 ... 450 451

Komentarze do niniejszej Instrukcji

Brak uwag

Avaya Business Secure Router 222 Configuration - Basics Instrukcja Użytkownika Strona 169

Komentarze do niniejszej Instrukcji

Powiązane produkty i podręczniki dla Routery Avaya Business Secure Router 222 Configuration - Basics