User`s guide

IP Filtering

7-3

8000-A2-GB21-10

June 1997

Security Advantages

Filtering provides security advantages on LANs as described in the following

subsections.

NOTE:

All upstream traffic from an ES is forwarded by the HotWire 5446 RTU to the

DSL card unless it is addressed to another ES (in the same subnet) on the

same LAN.

Management Traffic Leakage

Filtering can be used to prevent unwanted traffic from leaking into the

management domain. That is, filtering prevents ISP packets with management IP

destinations from being accepted for local delivery or routing.

For example, if the ISP network is 155.1.00.00 and the management network is

135.1.00.00, filters can be defined that would prevent any traffic entering from the

10BaseT port from being forwarded to the 135.1.00.00 network through the DSL

card.

ISP

97-1546

Router

10BaseT

MCC Card

DSL Card

135.1.00.00

155.1.00.00

NOTE:

Filters reduce packet throughput.

For instructions on how to set filters to prevent unwanted traffic from leaking into

the management domain, see Chapter 5 of the

HotWire Digital Subscriber Line

Access Multiplexer (DSLAM) User’s Guide

Service Security

Filtering on the upstream DSL ports can be used to ensure that only end-user

systems with valid IP addresses are able to route traffic to the ISP domain. That

is, filtering would block traffic from being routed upstream by another end-user

system that spoofs (attempts to gain access to another system by posing as an

authorized user) an IP address of an end-user system connected to a different

HotWire 5446 RTU.