Quick Reference Guide

54 | Chapter 4: Firewall Protection and Content Filtering
ProSafe Dual WAN Gigabit Firewall with SSL & IPsec VPN FVS336Gv2 Reference Manual
Configuring Other Firewall Features
You can configure attack checks, set session limits, and manage the Application Level
Gateway (ALG) for SIP sessions.
Attack Checks
The Attack Checks screen allows you to specify whether or not the VPN firewall should be
protected against common attacks in the LAN and WAN networks. To enable the appropriate
Attack Checks for your environment:
1. Select Security > Firewall from the menu and click Attack Checks to display the Attack
Checks screen (see ).
2. Check the boxes for the Attack Checks you wish to monitor. The various types of attack
checks are listed and defined below.
3. Click Apply to save your settings.
The various types of attack checks listed on the Attack Checks screen are:
• WAN Security Checks
- Respond To Ping On Internet Ports. By default, the VPN firewall responds to an
ICMP Echo (ping) packet coming from the Internet or WAN side. Responding to a
ping can be a useful diagnostic tool when there are connectivity problems. If the ping
option is enabled, you can allow either any IP address or a specific IP address only to
respond to a ping. You can disable the ping option to prevent hackers from easily
discovering the VPN firewall via a ping.
- Enable Stealth Mode. In stealth mode, the VPN firewall will not respond to port scans
from the WAN or Internet, which makes it less susceptible to discovery and attacks.
- Block TCP Flood. A SYN flood is a form of denial of service attack in which an
attacker sends a succession of SYN requests to a target system. When the system
responds, the attacker does not complete the connection, thus saturating the server
with half-open connections. No legitimate connections can then be made.