Chapter 10 Firewalls
163
Nortel Business Secure Router 252 Configuration — Basics
rule for this packet and it is not an attack, the
Action for packets that don’t
match firewall rules
field determines the action for this packet.
4
Based on the obtained state information, a firewall rule creates a temporary
access list entry that is inserted at the beginning of the WAN interface's
inbound extended access list. This temporary access list entry is designed to
permit inbound packets of the same connection as the outbound packet just
inspected.
5
The outbound packet is forwarded out through the interface.
6
Later, an inbound packet reaches the interface. This packet is part of the
connection previously established with the outbound packet. The inbound
packet is evaluated against the inbound access list, and is permitted because of
the temporary access list entry previously created.
7
The packet is inspected by a firewall rule, and the connection's state table
entry is updated as necessary. You can modify the inbound extended access
list temporary entries based on the updated state information, in order to
permit only packets that are valid for the current state of the connection.
8
Any additional inbound or outbound packets that belong to the connection are
inspected to update the state table entry and to modify the temporary inbound
access list entries as required, and are forwarded through the interface.
9
When the connection terminates or times out, the connection's state table
entry is deleted and the connection's temporary inbound access list entries are
deleted.
Stateful inspection and the Business Secure Router
Additional rules can be defined to extend or override the default rules. For
example, a rule can be created that will:
•
Block all traffic of a certain type, such as IRC (Internet Relay Chat), from the
LAN to the Internet.
•
Allow certain types of traffic from the Internet to specific hosts on the LAN.
•
Allow access to a Web server to everyone but competitors.
•
Restrict use of certain protocols, such as Telnet, to authorized users on the
LAN.
Содержание BSR252
Страница 28: ...28 Tables NN47923 500 ...
Страница 44: ...44 Chapter 1 Getting to know your Business Secure Router NN47923 500 ...
Страница 52: ...52 Chapter 2 Introducing the WebGUI NN47923 500 ...
Страница 70: ...70 Chapter 3 Wizard setup NN47923 500 ...
Страница 91: ...Chapter 5 System screens 91 Nortel Business Secure Router 252 Configuration Basics Figure 20 Time and Date ...
Страница 96: ...96 Chapter 5 System screens NN47923 500 ...
Страница 100: ...100 Chapter 6 LAN screens NN47923 500 Configuring IP Click LAN to open the IP screen Figure 22 LAN IP ...
Страница 111: ...Chapter 7 WAN screens 111 Nortel Business Secure Router 252 Configuration Basics Figure 26 WAN WAN ISP ...
Страница 114: ...114 Chapter 7 WAN screens NN47923 500 Figure 27 WAN IP ...
Страница 120: ...120 Chapter 7 WAN screens NN47923 500 Figure 31 Dial Backup Setup ...
Страница 128: ...128 Chapter 7 WAN screens NN47923 500 ...
Страница 152: ...152 Chapter 9 Static Route screens NN47923 500 ...
Страница 194: ...194 Chapter 11 Firewall screens NN47923 500 ...
Страница 210: ...210 Chapter 13 VPN NN47923 500 Figure 67 Summary IP Policies ...
Страница 222: ...222 Chapter 13 VPN NN47923 500 Figure 71 VPN Branch Office rule setup ...
Страница 231: ...Chapter 13 VPN 231 Nortel Business Secure Router 252 Configuration Basics Figure 72 VPN Branch Office IP Policy ...
Страница 249: ...Chapter 13 VPN 249 Nortel Business Secure Router 252 Configuration Basics Figure 78 VPN Client Termination ...
Страница 256: ...256 Chapter 13 VPN NN47923 500 Figure 81 VPN Client Termination advanced ...
Страница 260: ...260 Chapter 13 VPN NN47923 500 ...
Страница 264: ...264 Chapter 14 Certificates NN47923 500 Figure 83 My Certificates ...
Страница 270: ...270 Chapter 14 Certificates NN47923 500 Figure 85 My Certificate create ...
Страница 274: ...274 Chapter 14 Certificates NN47923 500 Figure 86 My Certificate details ...
Страница 282: ...282 Chapter 14 Certificates NN47923 500 Figure 89 Trusted CA details ...
Страница 298: ...298 Chapter 14 Certificates NN47923 500 ...
Страница 316: ...316 Chapter 16 IEEE 802 1x NN47923 500 ...
Страница 320: ...320 Chapter 17 Authentication server NN47923 500 Figure 106 Local User database edit ...
Страница 328: ...328 Chapter 17 Authentication server NN47923 500 ...
Страница 376: ...376 Chapter 20 Logs Screens NN47923 500 Figure 150 Log settings ...
Страница 386: ...386 Chapter 20 Logs Screens NN47923 500 ...
Страница 392: ...392 Chapter 21 Call scheduling screens NN47923 500 Figure 157 Applying Schedule Sets to a remote node ...
Страница 393: ...Chapter 21 Call scheduling screens 393 Nortel Business Secure Router 252 Configuration Basics ...
Страница 394: ...394 Chapter 21 Call scheduling screens NN47923 500 ...
Страница 409: ...Chapter 22 Maintenance 409 Nortel Business Secure Router 252 Configuration Basics Figure 170 Restart screen ...
Страница 410: ...410 Chapter 22 Maintenance NN47923 500 ...
Страница 430: ...430 Appendix A Troubleshooting NN47923 500 ...