The Dos Screen - ZyXEL Communications VMG Series User Manual

Table 105 Access Control: Add/Edit (continued)
LABEL
Select Service
Protocol
Custom Source
Port
Custom
Destination Port
TCP flag
Type
Policy
Direction
Enable Rate
Limit
Scheduler Rules
Cancel
OK

18.5 The DoS Screen

DoS (Denial of Service) attacks can flood your Internet connection with invalid packets and connection
requests, using so much bandwidth and so many resources that Internet access becomes unavailable.
Use the DoS screen to activate protection against DoS attacks. Click Security > Firewall > DoS to display
the following screen.
Chapter 18 Firewall
DESCRIPTION
Select the transport layer protocol that defines your customized port from the drop-down list
box. The specific protocol rule sets you add in the Security > Firewall > Protocol > Add screen
display in this list.
If you want to configure a customized protocol, select Specific Service.
This field is displayed only when you select Specific Protocol in Select Service.
Choose the IP port (TCP/UDP, TCP, UDP, ICMP, or ICMPv6) that defines your customized port from
the drop-down list box.
This field is displayed only when you select Specific Protocol in Select Service and have either
TCP or UDP in the Protocol field.
Enter a single port number or the range of port numbers of the source.
This field is displayed only when you select Specific Protocol in Select Service and have either
TCP or UDP in the Protocol field.
Enter a single port number or the range of port numbers of the destination.
This field is displayed only when you select Specific Protocol in Select Service and have TCP in
the Protocol field.
Select one of the following TCP flags: SYN (Synchronize), ACK (Acknowledge), URG (Urgent), PSH
(Push), RST (Reset), or FIN (Finished).
This field is displayed only when you select Specific Protocol in Select Service and ICMPv6 in the
protocol field.
From the drop-down list box, select which ICMPv6 type you would like to use.
Use the drop-down list box to select whether to discard (DROP), deny and send an ICMP
destination-unreachable message to the sender of (REJECT) or allow the passage of (ACCEPT)
packets that match this rule.
Use the drop-down list box to select the direction of traffic to which this rule applies.
Select this check box to set a limit on the upstream/downstream transmission rate for the
specified protocol.
Specify how many packets per minute or second the transmission rate is.
Select a schedule rule for this ACL rule form the drop-down list box. You can configure a new
schedule rule by click Add New ACL Rule. This will bring you to the Security > Scheduler Rules
screen.
Click Cancel to exit this screen without saving.
Click OK to save your changes.
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