Chapter 10 Firewalls
AMG1302-T10A User’s Guide
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Once these questions have been answered, adding rules is simply a matter of entering the
information into the correct fields in the web configurator screens.
10.4.4 Triangle Route
When the firewall is on, your Device acts as a secure gateway between your LAN and the Internet.
In an ideal network topology, all incoming and outgoing network traffic passes through the Device
to protect your LAN against attacks.
Figure 82
Ideal Firewall Setup
10.4.4.1 The “Triangle Route” Problem
A traffic route is a path for sending or receiving data packets between two Ethernet devices. You
may have more than one connection to the Internet (through one or more ISPs). If an alternate
gateway is on the LAN (and its IP address is in the same subnet as the Device’s LAN IP address),
the “triangle route” (also called asymmetrical route) problem may occur. The steps below describe
the “triangle route” problem.
1
A computer on the LAN initiates a connection by sending out a SYN packet to a receiving server on
the WAN.
2
The Device reroutes the SYN packet through Gateway
A
on the LAN to the WAN.
3
The reply from the WAN goes directly to the computer on the LAN without going through the
Device.
As a result, the Device resets the connection, as the connection has not been acknowledged.
Figure 83
“Triangle Route” Problem
1
2
WAN
LAN
1
2
3
WAN
LAN
A
ISP 1
ISP 2
Summary of Contents for AMG1302-T10A
Page 4: ...Contents Overview AMG1302 T10A User s Guide 4 ...
Page 12: ...Table of Contents AMG1302 T10A User s Guide 12 ...
Page 13: ...13 PART I User s Guide ...
Page 14: ...14 ...
Page 20: ...Chapter 1 Introduction AMG1302 T10A User s Guide 20 ...
Page 52: ...Chapter 4 Tutorials AMG1302 T10A User s Guide 52 ...
Page 53: ...53 PART II Technical Reference ...
Page 54: ...54 ...
Page 126: ...Chapter 8 Wireless LAN AMG1302 T10A User s Guide 126 ...
Page 140: ...Chapter 9 Network Address Translation NAT AMG1302 T10A User s Guide 140 ...
Page 158: ...Chapter 11 Filters AMG1302 T10A User s Guide 158 ...
Page 162: ...Chapter 12 Static Route AMG1302 T10A User s Guide 162 ...
Page 166: ...Chapter 13 Port Binding AMG1302 T10A User s Guide 166 ...
Page 176: ...Chapter 15 Quality of Service QoS AMG1302 T10A User s Guide 176 ...
Page 198: ...Chapter 18 Universal Plug and Play UPnP AMG1302 T10A User s Guide 198 ...
Page 202: ...Chapter 19 CWMP AMG1302 T10A User s Guide 202 ...
Page 206: ...Chapter 20 System Settings AMG1302 T10A User s Guide 206 ...
Page 216: ...Chapter 21 Logs AMG1302 T10A User s Guide 216 ...
Page 266: ...Appendix C Pop up Windows JavaScripts and Java Permissions AMG1302 T10A User s Guide 266 ...
Page 280: ...Appendix D Wireless LANs AMG1302 T10A User s Guide 280 ...
Page 290: ...Appendix E IPv6 AMG1302 T10A User s Guide 290 ...
Page 322: ...Appendix G Legal InformationSafety Warnings AMG1302 T10A User s Guide 322 ...