Chapter 9 Firewall Configuration
P-793H User’s Guide
145
The following table describes the labels in this screen.
9.10 DoS Thresholds
For DoS attacks, the ZyXEL Device uses thresholds to determine when to drop sessions that
do not become fully established. These thresholds apply globally to all sessions.
You can use the default threshold values, or you can change them to values more suitable to
your security requirements.
Refer to
to configure thresholds.
9.10.1 Threshold Values
Tune these parameters when something is not working and after you have checked the firewall
counters. These default values should work fine for most small offices. Factors influencing
choices for threshold values are:
• The maximum number of opened sessions.
• The minimum capacity of server backlog in your LAN network.
• The CPU power of servers in your LAN network.
• Network bandwidth.
• Type of traffic for certain servers.
If your network is slower than average for any of these factors (especially if you have servers
that are slow or handle many tasks and are often busy), then the default values should be
reduced.
You should make any changes to the threshold values before you continue configuring
firewall rules.
Table 44
Firewall > Anti Probing
LABEL
DESCRIPTION
Respond to PING
on
The ZyXEL Device does not respond to any incoming Ping requests when
Disable
is selected.
Select
LAN
to reply to incoming LAN Ping requests.
Select
WAN
to reply to incoming WAN Ping requests.
Otherwise select
LAN & WAN
to reply to both incoming LAN and WAN Ping
requests.
Do Not Respond
to Requests for
Unauthorized
Services.
Select this option to prevent hackers from finding the ZyXEL Device by probing for
unused ports. If you select this option, the ZyXEL Device will not respond to port
request(s) for unused ports, thus leaving the unused ports and the ZyXEL Device
unseen. By default this option is not selected and the ZyXEL Device will reply with
an ICMP Port Unreachable packet for a port probe on its unused UDP ports, and a
TCP Reset packet for a port probe on its unused TCP ports.
Note that the probing packets must first traverse the ZyXEL Device's firewall
mechanism before reaching this anti-probing mechanism. Therefore if the firewall
mechanism blocks a probing packet, the ZyXEL Device reacts based on the
corresponding firewall policy to send a TCP reset packet for a blocked TCP
packet or an ICMP port-unreachable packet for a blocked UDP packets or just
drop the packets without sending a response packet.
Apply
Click
Apply
to save your changes back to the ZyXEL Device.
Cancel
Click
Cancel
to begin configuring this screen afresh.
Summary of Contents for G.SHDSL.bis 4-port Security Gateway P-793H
Page 2: ......
Page 7: ...Safety Warnings P 793H User s Guide 7 This product is recyclable Dispose of it properly ...
Page 8: ...Safety Warnings P 793H User s Guide 8 ...
Page 30: ...List of Figures P 793H User s Guide 30 ...
Page 36: ...List of Tables P 793H User s Guide 36 ...
Page 38: ...38 ...
Page 68: ...Chapter 4 Point to 2 point Configuration P 793H User s Guide 68 ...
Page 70: ...70 ...
Page 114: ...Chapter 7 Network Address Translation NAT Screens P 793H User s Guide 114 ...
Page 116: ...116 ...
Page 152: ...Chapter 10 Content Filtering P 793H User s Guide 152 ...
Page 180: ...Chapter 12 Static Route P 793H User s Guide 180 ...
Page 194: ...Chapter 14 Dynamic DNS Setup P 793H User s Guide 194 ...
Page 216: ...Chapter 16 Universal Plug and Play UPnP P 793H User s Guide 216 ...
Page 217: ...217 PART IV Maintenance System 219 Logs 225 Tools 229 Diagnostic 235 ...
Page 218: ...218 ...
Page 224: ...Chapter 17 System P 793H User s Guide 224 ...
Page 234: ...Chapter 19 Tools P 793H User s Guide 234 ...
Page 238: ...238 ...
Page 244: ...Chapter 21 Introducing the SMT P 793H User s Guide 244 ...
Page 248: ...Chapter 22 General Setup P 793H User s Guide 248 ...
Page 256: ...Chapter 23 WAN Setup P 793H User s Guide 256 ...
Page 262: ...Chapter 24 LAN Setup P 793H User s Guide 262 ...
Page 278: ...Chapter 27 Static Route Setup P 793H User s Guide 278 ...
Page 308: ...Chapter 30 Filter Configuration P 793H User s Guide 308 ...
Page 310: ...Chapter 31 SNMP Configuration P 793H User s Guide 310 ...
Page 312: ...Chapter 32 System Password P 793H User s Guide 312 ...
Page 322: ...Chapter 33 System Information Diagnosis P 793H User s Guide 322 ...
Page 352: ...Chapter 37 Schedule Setup P 793H User s Guide 352 ...
Page 360: ...360 ...
Page 366: ...Appendix B Wall mounting Instructions P 793H User s Guide 366 ...
Page 400: ...Appendix F IP Address Assignment Conflicts P 793H User s Guide 400 ...
Page 404: ...Appendix G Common Services P 793H User s Guide 404 ...
Page 432: ...Appendix K Legal Information P 793H User s Guide 432 ...
Page 443: ...Index P 793H User s Guide 443 ...
Page 444: ...Index P 793H User s Guide 444 ...