Chapter 11 Firewall
ZyWALL 2WG User’s Guide
263
The following table describes the labels in this screen.
Table 73
SECURITY > FIREWALL > Threshold
LABEL
DESCRIPTION
Disable DoS Attack
Protection on
Select the check boxes of any interfaces (or all VPN tunnels) for which you want
the ZyWALL to not use the Denial of Service protection thresholds. This disables
DoS protection on the selected interface (or all VPN tunnels).
You may want to disable DoS protection for an interface if the ZyWALL is treating
valid traffic as DoS attacks. Another option would be to raise the thresholds.
Denial of Service
Thresholds
The ZyWALL measures both the total number of existing half-open sessions and
the rate of session establishment attempts. Both TCP and UDP half-open
sessions are counted in the total number and rate measurements. Measurements
are made once a minute.
One Minute Low
This is the rate of new half-open sessions per minute that causes the firewall to
stop deleting half-open sessions. The ZyWALL continues to delete half-open
sessions as necessary, until the rate of new connection attempts drops below this
number.
One Minute High
This is the rate of new half-open sessions per minute that causes the firewall to
start deleting half-open sessions. When the rate of new connection attempts rises
above this number, the ZyWALL deletes half-open sessions as required to
accommodate new connection attempts.
For example, if you set the one minute high to 100, the ZyWALL starts deleting
half-open sessions when more than 100 session establishment attempts have
been detected in the last minute. It stops deleting half-open sessions when the
number of session establishment attempts detected in a minute goes below the
number set as the one minute low.
Maximum
Incomplete Low
This is the number of existing half-open sessions that causes the firewall to stop
deleting half-open sessions. The ZyWALL continues to delete half-open requests
as necessary, until the number of existing half-open sessions drops below this
number.
Maximum
Incomplete High
This is the number of existing half-open sessions that causes the firewall to start
deleting half-open sessions. When the number of existing half-open sessions
rises above this number, the ZyWALL deletes half-open sessions as required to
accommodate new connection requests. Do not set
Maximum Incomplete High
to lower than the current
Maximum Incomplete
Low
number.
For example, if you set the maximum incomplete high to 100, the ZyWALL starts
deleting half-open sessions when the number of existing half-open sessions rises
above 100. It stops deleting half-open sessions when the number of existing half-
open sessions drops below the number set as the maximum incomplete low.
TCP Maximum
Incomplete
An unusually high number of half-open sessions with the same destination host
address could indicate that a DoS attack is being launched against the host.
Specify the number of existing half-open TCP sessions with the same destination
host IP address that causes the firewall to start dropping half-open sessions to
that same destination host IP address. Enter a number between 1 and 256. As a
general rule, you should choose a smaller number for a smaller network, a slower
system or limited bandwidth. The ZyWALL sends alerts whenever the
TCP
Maximum Incomplete
is exceeded.
Action taken when
TCP Maximum
Incomplete
reached threshold
Select the action that ZyWALL should take when the TCP maximum incomplete
threshold is reached. You can have the ZyWALL either:
Delete the oldest half open session when a new connection request comes.
or
Deny new connection requests for the number of minutes that you specify
(between 1 and 256).
Apply
Click
Apply
to save your changes back to the ZyWALL.
Reset Click
Reset
to begin configuring this screen afresh.
Summary of Contents for ZYWALL 2 WG
Page 2: ......
Page 8: ...Safety Warnings ZyWALL 2WG User s Guide 8 ...
Page 42: ...List of Figures ZyWALL 2WG User s Guide 42 ...
Page 50: ...List of Tables ZyWALL 2WG User s Guide 50 ...
Page 52: ...52 ...
Page 80: ...Chapter 2 Introducing the Web Configurator ZyWALL 2WG User s Guide 80 ...
Page 100: ...Chapter 3 Wizard Setup ZyWALL 2WG User s Guide 100 ...
Page 140: ...Chapter 4 Tutorial ZyWALL 2WG User s Guide 140 ...
Page 146: ...146 ...
Page 158: ...Chapter 6 LAN Screens ZyWALL 2WG User s Guide 158 ...
Page 171: ...Chapter 8 WAN Screens ZyWALL 2WG User s Guide 171 Figure 108 NETWORK WAN General ...
Page 200: ...Chapter 8 WAN Screens ZyWALL 2WG User s Guide 200 ...
Page 238: ...238 ...
Page 300: ...Chapter 13 Content Filtering Reports ZyWALL 2WG User s Guide 300 ...
Page 348: ...Chapter 14 IPSec VPN ZyWALL 2WG User s Guide 348 ...
Page 378: ...Chapter 15 Certificates ZyWALL 2WG User s Guide 378 ...
Page 384: ...384 ...
Page 426: ...Chapter 20 Bandwidth Management ZyWALL 2WG User s Guide 426 ...
Page 479: ...479 PART V Logs and Maintenance Logs Screens 481 Maintenance 511 ...
Page 480: ...480 ...
Page 485: ...Chapter 26 Logs Screens ZyWALL 2WG User s Guide 485 Figure 304 LOGS Log Settings ...
Page 510: ...Chapter 26 Logs Screens ZyWALL 2WG User s Guide 510 ...
Page 530: ...530 ...
Page 558: ...Chapter 30 WAN and Dial Backup Setup ZyWALL 2WG User s Guide 558 ...
Page 564: ...Chapter 31 LAN Setup ZyWALL 2WG User s Guide 564 ...
Page 570: ...Chapter 32 Internet Access ZyWALL 2WG User s Guide 570 ...
Page 574: ...Chapter 33 DMZ Setup ZyWALL 2WG User s Guide 574 ...
Page 578: ...Chapter 34 Route Setup ZyWALL 2WG User s Guide 578 ...
Page 582: ...Chapter 35 Wireless Setup ZyWALL 2WG User s Guide 582 ...
Page 594: ...Chapter 37 IP Static Route Setup ZyWALL 2WG User s Guide 594 ...
Page 614: ...Chapter 38 Network Address Translation NAT ZyWALL 2WG User s Guide 614 ...
Page 632: ...Chapter 40 Filter Configuration ZyWALL 2WG User s Guide 632 ...
Page 668: ...Chapter 44 System Maintenance Menus 8 to 10 ZyWALL 2WG User s Guide 668 ...
Page 672: ...Chapter 45 Remote Management ZyWALL 2WG User s Guide 672 ...
Page 680: ...Chapter 46 IP Policy Routing ZyWALL 2WG User s Guide 680 ...
Page 686: ...686 ...
Page 692: ...Chapter 48 Troubleshooting ZyWALL 2WG User s Guide 692 ...
Page 702: ...Chapter 49 Product Specifications ZyWALL 2WG User s Guide 702 ...
Page 704: ...704 ...
Page 712: ...Appendix A Pop up Windows JavaScripts and Java Permissions ZyWALL 2WG User s Guide 712 ...
Page 740: ...Appendix D Common Services ZyWALL 2WG User s Guide 740 ...
Page 768: ...Appendix G Legal Information ZyWALL 2WG User s Guide 768 ...
Page 774: ...Appendix H Customer Support ZyWALL 2WG User s Guide 774 ...