Typical Configuration Examples Of Packet Filter - 3Com 3C13636 Configuration Manual

3Com Router 3000 Ethernet Family
Configuration Guide

6.2.6 Typical Configuration Examples of Packet Filter

I. Network requirements
The following example of configuring firewall in a company explains firewall
configuration.
The company accesses the internet through the interface Serial1/0/0 on a 3Com router.
It provides WWW, FTP and Telnet services externally. The internal subnet of the
company is 129.38.1.0, the internal FTP server address is 129.38.1.1, internal Telnet
server address is 129.38.1.2, internal WWW server address is 129.38.1.3 and
company external address is 202.38.160.1. Address translation is configured on the
router so that internal PCs could access the Internet and external PCs could access
internal server. The following requirements are aimed to be satisfied through
configuration firewall:
Only specific subscribers on external network can access the internal server.
Only specific hosts on the internal network can access external network.
Suppose the IP address of the specific external subscriber is 202.39.2.3.
II. Network diagram
Figure 6-3 Network diagram of packet filter configuration example
III. Configuration procedure
# Enable firewall.
[3Com] firewall enable
# Set the default firewall filtering mode as permitting packet to pass.
[3Com] firewall default permit
# Create ACL 3001.
3Com Corporation
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Chapter 6 Firewall Configuration