Netopia 4752 Benutzerhandbuch
Security 13-19
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:
(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.
80 for WWW.
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 However, the filters in the deleted set are no longer in
effect (unless they are par t of another set).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.
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.
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.
por ts, or the TCP ACK bit.
Port: A number that defines a par ticular type of ser vice.