Prestige 792H User’s Guide
8-8
Firewall
Allows all sessions originating from the LAN (local network) to the WAN (Internet).
Denies all sessions originating from the WAN to the LAN.
Figure 8-5 Stateful Inspection
The previous figure shows the Prestige’s default firewall rules in action as well as demonstrates how stateful
inspection works. User A can initiate a Telnet session from within the LAN and responses to this request are
allowed. However other Telnet traffic initiated from the WAN is blocked.
8.5.1 Stateful Inspection Process
In this example, the following sequence of events occurs when a TCP packet leaves the LAN network
through the firewall's WAN interface. The TCP packet is the first in a session, and the packet's application
layer protocol is configured for a firewall rule inspection:
1. The packet travels from the firewall's LAN to the WAN.
2. The packet is evaluated against the interface's existing outbound access list, and the packet is
permitted (a denied packet would simply be dropped at this point).
3. The packet is inspected by a firewall rule to determine and record information about the state of the
packet's connection. This information is recorded in a new state table entry created for the new
connection. If there is not a firewall rule for this packet and it is not an attack, then
The default
action for packets not matching following rules
field (see
Figure 10-4
) determines the action for
this packet.
Содержание Prestige 792H
Страница 1: ...Prestige 792H G SHDSL 4 port Security Gateway User s Guide Version 3 40 BZ 0 March 2004...
Страница 8: ......
Страница 32: ......
Страница 34: ......
Страница 40: ......
Страница 46: ......
Страница 66: ......
Страница 86: ...Prestige 792H User s Guide 5 14 WAN Setup Figure 5 6 Advanced WAN Backup...
Страница 94: ......
Страница 108: ......
Страница 112: ......
Страница 134: ......
Страница 163: ...VPN IPSec IV Part IV VPN IPSec This part provides information about configuring VPN IPSec for secure communications...
Страница 164: ......
Страница 178: ...Prestige 792H User s Guide 14 8 VPN Screens Figure 14 3 VPN IKE...
Страница 205: ...Remote Management and UPnP V Part V Remote Management and UPnP This part contains Remote Management and UPnP...
Страница 206: ......
Страница 210: ......
Страница 220: ......
Страница 221: ...Maintenance VI Part VI Maintenance This part covers the maintenance screens...
Страница 222: ......
Страница 234: ......
Страница 236: ......
Страница 246: ......
Страница 268: ......
Страница 270: ......
Страница 282: ......
Страница 286: ......
Страница 312: ......
Страница 334: ......
Страница 348: ......
Страница 370: ......
Страница 380: ......
Страница 388: ......
Страница 390: ......
Страница 406: ......
Страница 410: ......
Страница 415: ...XI Part XI Appendices and Index This section provides some Appendices and an Index...
Страница 416: ......
Страница 420: ......
Страница 424: ......
Страница 426: ......
Страница 430: ......