Chapter 9 Firewalls

Figure 89 Security > Firewall > Rules: Edit: Edit Customized Services: Config

The following table describes the labels in this screen.

Table 56 Security > Firewall > Rules: Edit: Edit Customized Services: Config

LABEL

DESCRIPTION

Config

 

 

 

Service Name

Type a unique name for your custom port.

 

 

Service Type

Choose the IP port (TCP, UDP or TCP/UDP) that defines your customized port from

 

the drop down list box.

 

 

Port Configuration

 

 

Type

Click Single to specify one port only or Range to specify a span of ports that define

 

your customized service.

 

 

Port Number

Type a single port number or the range of port numbers that define your customized

 

service.

 

 

Back

Click this to return to the previous screen without saving.

 

 

Apply

Click this to save your changes.

 

 

Cancel

Click this to restore your previously saved settings.

 

 

Delete

Click this to delete the current rule.

 

 

9.4 The Firewall Threshold Screen

For DoS attacks, the ZyXEL Device uses thresholds to determine when to start dropping sessions that do not become fully established (half-open sessions). These thresholds apply globally to all sessions.

For TCP, half-open means that the session has not reached the established state-the TCP three- way handshake has not yet been completed. Under normal circumstances, the application that initiates a session sends a SYN (synchronize) packet to the receiving server. The receiver sends back an ACK (acknowledgment) packet and its own SYN, and then the initiator responds with an ACK (acknowledgment). After this handshake, a connection is established.

 

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P-660HN-F1 User’s Guide