Netopia 4541 - Manual (Page 164)

11-20 User’s Reference Guide
FTP sessions. To allow WAN-originated FTP sessions to a LAN-based FTP ser ver with the IP address a.b.c.d
(corresponding to a numbered IP address such as 163.176.8.243), inser t the following input filter ahead of the
current input filter 1:
■ Enabled: Yes
■ For ward: 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 Por t Comparison: No Compare
■ Source Por t ID: 0
■ Dest. Por t Comparison: Equal
■ Dest. Por t ID: 21
Note: A similar filter could be used to permit Telnet or WWW access. Set the Dest. Por t 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 However, the filters in the deleted set are no
longer in effect (unless they are par t of another set).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
por ts, or the TCP ACK bit.
Port: A number that defines a par ticular type of ser vice.