Netopia 4541, 4542 manual Firewall tutorial General firewall terms

11-20 User’s Reference Guide

FTP sessions. To allow WAN-originated FTP sessions to a LAN-based FTP server with the IP address a.b.c.d (corresponding to a numbered IP address such as 163.176.8.243), insert the following input filter ahead of the current input filter 1:

■Enabled: Yes

■Forward: Yes

■Source IP Address: 0.0.0.0

■Source IP Address Mask: 0.0.0.0

■Dest. IP Address: a.b.c.d

■Dest. IP Address Mask: 255.255.255.255

■Protocol Type: TCP

■Source Port Comparison: No Compare

■Source Port ID: 0

■Dest. Port Comparison: Equal

■Dest. Port ID: 21

Note: A similar filter could be used to permit Telnet or WWW access. Set the Dest. Port ID to 23 for Telnet or to 80 for WWW.

Note: Deleting a filter set does not delete the filters in that set. However, the filters in the deleted set are no longer in effect (unless they are part of another set). The deleted set will no longer appear in the answer profile or any connection profiles to which it was added.

Firewall tutorial

General firewall terms

Filter rule: A filter set is comprised of individual filter rules.

Filter set: A grouping of individual filter rules.

Firewall: A component or set of components that restrict access between a protected network and the Internet, or between two networks.

Host: A workstation on the network.

Packet: Unit of communication on the Internet.

Packet filter: Packet filters allow or deny packets based on source or destination IP addresses, TCP or UDP ports, or the TCP ACK bit.

Port: A number that defines a particular type of service.