To configure advanced access rule options, select
Firewall > Advanced
under Firewall.
The
Firewall > Advanced
page includes the following firewall configuration option groups:
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Enable Stealth Mode
- By default, the security appliance responds to incoming connection requests as either “blocked” or “open.” If you enable Stealth Mode, your security appliance does not respond to blocked inbound connection requests
. Stealth Mode makes your security appliance essentially invisible to hackers.
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Randomize IP ID
- Select Randomize IP ID to prevent hackers using various detection tools from detecting the presence of a security appliance. IP packets are given random IP IDs, which makes it more difficult for hackers to “fingerprint” the security appliance.
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Decrement IP TTL for forwarded traffic
- Time-to-live (TTL) is a value in an IP packet that tells a network router whether or not the packet has been in the network too long and should be discarded. Select this option to decrease the TTL value for packets that have been forwarded and therefore have already been in the network for some time.
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Never generate ICMP Time-Exceeded packets
- The SonicWALL appliance generates Time-Exceeded packets to report when it has dropped a packet because its TTL value has decreased to zero. Select this option if you do not want the SonicWALL appliance to generate these reporting packets.
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Enable RTSP Transformations
- Select this option to support on-demand delivery of real-time data, such as audio and video. RTSP (Real Time Streaming Protocol) is an application-level protocol for control over delivery of data with real-time properties.
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Drop Source Routed Packets
- (Enabled by default.) Clear this check box if you are testing traffic between two specific hosts and you are using source routing.
The Connections section provides the ability to fine-tune the performance of the appliance to
prioritize either optimal performance or support for an increased number of simultaneous connections that are inspected by UTM services.
Force inbound and outbound FTP data connections to use default port 20
- The default configuration allows FTP connections from port 20 but remaps outbound traffic to a port such as 1024. If the check box is selected, any FTP data connection through the security appliance must come from port 20 or the connection is dropped. The event is then logged as a log event on the security appliance.
Apply firewall rules for intra-LAN traffic to/from the same interface
- Applies firewall rules that is received on a LAN interface and that is destined for the same LAN interface. Typically, this only necessary when secondary LAN subnets are configured.
Default UDP Connection Timeout (seconds)
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Enter the number of seconds of idle time you want to allow before UDP connections time out. This value is overridden by the UDP Connection timeout you set for individual rules.
The Connection Limiting feature provides an additional layer of security against distributed
denial of service (DDoS) attacks by limiting the number of connections that can be initiated from or to individual IP addresses.
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Enable connection limit based on source IP
- Select to limit the number of connections that can be made from a single source IP address. By default, the limit is set to 128. To modify this, enter a value in the Threshold
field.
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Enable connection limit based on destination IP
- Select to limit the number of connections that can be made to a single destination IP address. By default, the limit is set to 128. To modify this, enter a value in the Threshold
field.
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In addition to these configurable settings for individual IP addresses, all SonicWALL security
appliances have a built-in limit on the total number of connections allowed. For more information on this feature, see “Connection Limiting Overview”
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