Chapter 46: Configuring Access Rules

Firewall > Access Rules

This chapter provides an overview on your SonicWALL security appliance stateful packet inspection default access rules and configuration examples to customize your access rules to meet your business requirements.

Access rules are network management tools that allow you to define inbound and outbound access policy, configure user authentication, and enable remote management of the SonicWALL security appliance.

The SonicOS Firewall > Access Rules page provides a sortable access rule management interface. The subsequent sections provide high-level overviews on configuring access rules by zones and configuring bandwidth management using access rules:

• Stateful Packet Inspection Default Access Rules Overview
• Using Bandwidth Management with Access Rules Overview
• Access Rule Configuration Task List

Stateful Packet Inspection Default Access Rules Overview

By default, the SonicWALL security appliance’s stateful packet inspection allows all communication from the LAN to the Internet, and blocks all traffic to the LAN from the Internet. The following behaviors are defined by the “Default” stateful inspection packet access rule enabled in the SonicWALL security appliance:

• Allow all sessions originating from the LAN, WLAN to the WAN, or DMZ (except when the destination WAN IP address is the WAN interface of the SonicWALL appliance itself)
• Allow all sessions originating from the DMZ to the WAN.
• Deny all sessions originating from the WAN to the DMZ.
• Deny all sessions originating from the WAN and DMZ to the LAN or WLAN.

Additional network access rules can be defined to extend or override the default access rules. For example, access rules can be created that allow access from the LAN zone to the WAN Primary IP address, or block certain types of traffic such as IRC from the LAN to the WAN, or allow certain types of traffic, such as Lotus Notes database synchronization, from specific hosts on the Internet to specific hosts on the LAN, or restrict use of certain protocols such as Telnet to authorized users on the LAN.

Custom access rules evaluate network traffic source IP addresses, destination IP addresses, IP protocol types, and compare the information to access rules created on the SonicWALL security appliance. Network access rules take precedence, and can override the SonicWALL security appliance’s stateful packet inspection. For example, an access rule that blocks IRC traffic takes precedence over the SonicWALL security appliance default setting of allowing this type of traffic.

Caution: The ability to define network access rules is a very powerful tool. Using custom access rules can disable firewall protection or block all access to the Internet. Use caution when creating or deleting network access rules.

Using Bandwidth Management with Access Rules Overview

Bandwidth management (BWM) allows you to assign guaranteed and maximum bandwidth to services and prioritize traffic on all BWM-enabled interfaces. Using access rules, BWM can be applied on specific network traffic. Packets belonging to a bandwidth management enabled policy will be queued in the corresponding priority queue before being sent on the bandwidth management-enabled interface. All other packets will be queued in the default queue and will be sent in a First In and First Out (FIFO) manner (a storage method that retrieves the item stored for the longest time).

Example Scenario

If you create an access rule for outbound mail traffic (such as SMTP) and enable bandwidth management with the following parameters:

• Guaranteed bandwidth of 20%
• Maximum bandwidth of 40%
• Priority of 0 (zero)

The outbound SMTP traffic is guaranteed 20% of available bandwidth available to it and can get as much as 40% of available bandwidth. If SMTP traffic is the only BWM enabled rule:

• When SMTP traffic is using its maximum configured bandwidth (which is the 40% maximum described above), all other traffic gets the remaining 60% of bandwidth.
• When SMTP traffic is using less than its maximum configured bandwidth, all other traffic gets between 60% and 100% of the link bandwidth.

Now consider adding the following BWM-enabled rule for FTP:

• Guaranteed bandwidth of 60%
• Maximum bandwidth of 70%
• Priority of 1

When configured along with the previous SMTP rule, the traffic behaves as follows:

• 60% of total bandwidth is always reserved for FTP traffic (because of its guarantee). 20% of total bandwidth is always reserved for SMTP traffic (because of its guarantee).
• SMTP traffic can use up to 40% of total bandwidth (because it has a higher priority than FTP), which, when combined with FTP’s 60% guarantee, results in no other traffic being sent, because all 100% of the bandwidth is being used by higher priority traffic.
• If SMTP traffic reduces and only uses 10% of total bandwidth, then FTP can use up to 70% and all the other traffic gets the remaining 20%.
• If SMTP traffic stops, FTP gets 70% and all other traffic gets the remaining 30% of bandwidth.
• If FTP traffic has stopped, SMTP gets 40% and all other traffic get the remaining 60% of bandwidth.

Note: When the Bandwidth Management Type on the Firewall Services > BWM page is set to WAN: Access rules using bandwidth management have a higher priority than access rules not using bandwidth management. Access rules without bandwidth management are given lowest priority. When the Bandwidth Management Type is set to Global, the default priority is Medium (4).

Tip: You must configure Bandwidth Management individually for each interface on the Network > Interfaces page. Click the Configure icon for the interface, and select the Advanced tab. Enter your available egress and ingress bandwidths in the Available interface Egress Bandwidth (Kbps) and Available interface Ingress Bandwidth (Kbps) fields, respectively. This applies when the Bandwidth Management Type on the Firewall Services > BWM page is set to either WAN or Global.

Access Rule Configuration Task List

This section provides a list of the following configuration tasks:

• Displaying Access Rules with View Styles
• Configuring Access Rules for a Zone
• Adding Access Rules
• Editing an Access Rule
• Deleting an Access Rule
• Enabling and Disabling an Access Rule
• Restoring Access Rules to Default Zone Settings
• Displaying Access Rule Traffic Statistics
• Connection Limiting Overview
• Access Rule Configuration Examples

Displaying Access Rules with View Styles

Access rules can be displayed in multiple views using SonicOS. You can select the type of view from the selections in the View Style section. The following View Styles are available:

• All Rules - Select All Rules to display all access rules configured on the SonicWALL security appliance.
• Matrix - Displays as From/To with LAN, WAN, VPN, or other interface in the From row, and LAN, WAN, VPN, or other interface in the To column. Select the Edit icon
  
  
  
  in the table cell to view the access rules.
• Drop-down Boxes - Displays two pull-down menus: From Zone and To Zone. Select an interface from the From Zone menu and select an interface from the To Zone menu. Click OK and access rules defined for the two interfaces are displayed.

Tip: You can also view access rules by zones. Use the Option checkboxes in the From Zone and To Zone column. Select LAN, WAN, VPN, ALL from the From Zone column. And then select LAN, WAN, VPN, ALL from the To Zone column. Click OK to display the access rules.

Each view displays a table of defined network access rules. For example, selecting All Rules displays all the network access rules for all zones.

Configuring Access Rules for a Zone

To display the Access Rules for a specific zone, select a zone from the Matrix, Drop-down Boxes, or All Rules view.

The access rules are sorted from the most specific at the top, to less specific at the bottom of the table. At the bottom of the table is the Any rule. The default access rule is all IP services except those listed in the Access Rules page. Access rules can be created to override the behavior of the Any rule; for example, the Any rule allows users on the LAN to access all Internet services, including NNTP News.

You can change the priority ranking of an access rule by clicking the Arrows icon in the Priority column. The Change Priority window is displayed. Enter the new priority number (1-10) in the Priority field, and click OK.

Tip: If the Delete or Edit icons are dimmed (unavailable), the access rule cannot be changed or deleted from the list.

Adding Access Rules

To add access rules to the SonicWALL security appliance, perform the following steps:

1. Click Add at the bottom of the Access Rules table. The Add Rule window is displayed.





2. In the General tab, select Allow | Deny | Discard from the Action list to permit or block IP traffic.
3. Select the from and to zones from the From Zone and To Zone menus.
4. Select the service or group of services affected by the access rule from the Service list. The Default service encompasses all IP services.
   If the service is not listed, you must define the service in the Add Service window. Select Create New Service or Create New Group to display the Add Service window or Add Service Group window.
5. Select the source of the traffic affected by the access rule from the Source list. Selecting Create New Network displays the Add Address Object window.
6. If you want to define the source IP addresses that are affected by the access rule, such as restricting certain users from accessing the Internet, type the starting IP addresses of the address range in the Address Range Begin field and the ending IP address in the Address Range End field. To include all IP addresses, type * in the Address Range Begin field.
7. Select the destination of the traffic affected by the access rule from the Source list. Selecting Create New Network displays the Add Address Object window.
8. From the Users Allowed menu, add the user or user group affected by the access rule.
9. Select a schedule from the Schedule menu. The default schedule is Always on.
10. Enter any comments to help identify the access rule in the Comments field.
11. The Allow Fragmented Packets check box is enabled by default. Large IP packets are often divided into fragments before they are routed over the Internet and then reassembled at a destination host. One reason to disable this setting is because it is possible to exploit IP fragmentation in Denial of Service (DoS) attacks.
12. Click on the Advanced tab.





13. If you would like for the access rule to timeout after a period of TCP inactivity, set the amount of time, in minutes, in the TCP Connection Inactivity Timeout (minutes) field. The default value is 5 minutes.
14. If you would like for the access rule to timeout after a period of UDP inactivity, set the amount of time, in minutes, in the UDP Connection Inactivity Timeout (minutes) field. The default value is 30 minutes.
15. Specify the number of connections allowed as a percent of maximum number of connections allowed by the SonicWALL security appliance in the Number of connections allowed (% of maximum connections) field. Refer to Connection Limiting Overview for more information on connection limiting.
16. Select Create a reflexive rule if you want to create a matching access rule to this one in the opposite direction--from your destination zone or address object to your source zone or address object.
17. Click on the QoS tab if you want to apply DSCP or 802.1p Quality of Service management to traffic governed by this rule. See 802.1p and DSCP QoS for more information on managing QoS marking in access rules.





18. Under DSCP Marking Settings select the DSCP Marking Action. You can select None, Preserve, Explicit, or Map. Preserve is the default.
• None: DSCP values in packets are reset to 0.
• Preserve: DSCP values in packets will remain unaltered.
• Explicit: Set the DSCP value to the value you select in the Explicit DSCP Value field. This is a numeric value between 0 and 63. Some of the standard values are:
• 0 - Best effort/Default (default)
• 8 - Class 1
• 10 - Class 1, Gold (AF11)
• 12 - Class 1, Silver (AF12)
• 14 - Class 1, Bronze (AF13)
• 16 - Class 2
• 18 - Class 2, Gold (AF21)
• 20 - Class 2, Silver (AF22)
• 22 - Class 2, Bronze (AF23)
• 24 - Class 3
• 26 - Class 3, Gold (AF31)
• 27 - Class 3, Silver (AF32)
• 30 - Class 3, Bronze (AF33)
• 32 - Class 4
• 34 - Class 4, Gold (AF41)
• 36 - Class 4, Silver (AF42)
• 38 - Class 4, Bronze (AF43)
• 40 - Express Forwarding
• 46 - Expedited Forwarding (EF)
• 48 - Control
• 56 - Control
• Map: The QoS mapping settings on the Firewall > QoS Mapping page will be used. See 802.1p and DSCP QoS for instructions on configuring the QoS Mapping. If you select Map, you can select Allow 802.1p Marking to override DSCP values.
19. Under 802.1p Marking Settings select the 802.1p Marking Action. You can select None, Preserve, Explicit, or Map. None is the default.
• None: No 802.1p tagging is added to the packets.
• Preserve: 802.1p values in packets will remain unaltered.
• Explicit: Set the 802.1p value to the value you select in the Explicit 802.1p Value field. This is a numeric value between 0 and 7. The standard values are:
• 0 - Best effort (default)
• 1 - Background
• 2 - Spare
• 3 - Excellent effort
• 4 - Controlled load
• 5 - Video (<100ms latency)
• 6 - Voice (<10ms latency)
• 7 - Network control
• Map: The QoS mapping settings on the Firewall > QoS Mapping page will be used. See 802.1p and DSCP QoS for instructions on configuring the QoS Mapping.
20. Click OK to add the rule.

Tip: Although custom access rules can be created that allow inbound IP traffic, the SonicWALL security appliance does not disable protection from DoS attacks, such as the SYN Flood and Ping of Death attacks.

Editing an Access Rule

To display the Edit Rule window (includes the same settings as the Add Rule window), click the Edit icon.

Deleting an Access Rule

To delete the individual access rule, click on the Delete icon. To delete all the checkbox selected access rules, click the Delete button.

Enabling and Disabling an Access Rule

To enable or disable an access rule, click the Enable checkbox.

Restoring Access Rules to Default Zone Settings

To remove all end-user configured access rules for a zone, click the Default button. This will restore the access rules for the selected zone to the default access rules initially setup on the SonicWALL security appliance.

Displaying Access Rule Traffic Statistics

Move your mouse pointer over the Graph icon to display the following access rule receive (Rx) and transmit (Tx) traffic statistics:

• Rx Bytes
• Rx Packets
• Tx Bytes
• Tx Packets

Connection Limiting Overview

The Connection Limiting feature is intended to offer an additional layer of security and control when coupled with such SonicOS features as SYN Cookies and Intrusion Prevention Services (IPS). Connection limiting provides a means of throttling connections through the SonicWALL using Access Rules as a classifier, and declaring the maximum percentage of the total available connection cache that can be allocated to that class of traffic.

Coupled with IPS, this can be used to mitigate the spread of a certain class of malware as exemplified by Sasser, Blaster, and Nimda. These worms propagate by initiating connections to random addresses at atypically high rates. For example, each host infected with Nimda attempted 300 to 400 connections per second, Blaster sent 850 packets per second, and Sasser was capable of 5,120 attempts per second. Typical, non-malicious network traffic generally does not establish anywhere near these numbers, particularly when it is Trusted ->Untrusted traffic (i.e. LAN->WAN). Malicious activity of this sort can consume all available connection-cache resources in a matter of seconds, particularly on smaller appliances.

In addition to mitigating the propagation of worms and viruses, Connection limiting can be used to alleviate other types of connection-cache resource consumption issues, such as those posed by uncompromised internal hosts running peer-to-peer software (assuming IPS is configured to allow these services), or internal or external hosts using packet generators or scanning tools.

Note: The maximum number of connections a SonicWALL security appliance can support depends on the specific configuration, including whether App Flow is enabled and if an external collector is configured, as well as the physical capabilities of the particular model on the SonicWALL security appliance. For more information see the Connections section.

Finally, connection limiting can be used to protect publicly available servers (e.g. Web servers) by limiting the number of legitimate inbound connections permitted to the server (i.e. to protect the server against the Slashdot-effect). This is different from SYN flood protection which attempts to detect and prevent partially-open or spoofed TCP connection. This will be most applicable for Untrusted traffic, but it can be applied to any zone traffic as needed.

Connection limiting is applied by defining a percentage of the total maximum allowable connections that may be allocated to a particular type of traffic. The above figures show the default LAN ->WAN setting, where all available resources may be allocated to LAN->WAN (any source, any destination, any service) traffic.

More specific rules can be constructed; for example, to limit the percentage of connections that can be consumed by a certain type of traffic (e.g. FTP traffic to any destination on the WAN), or to prioritize important traffic (e.g. HTTPS traffic to a critical server) by allowing 100% to that class of traffic, and limiting general traffic to a smaller percentage (minimum allowable value is 1%).

Note: It is not possible to use IPS signatures as a connection limiting classifier; only Access Rules (i.e. Address Objects and Service Objects) are permissible.

Access Rule Configuration Examples

This section provides configuration examples on adding network access rules:

• Enabling Ping
• Blocking LAN Access for Specific Services
• Allowing WAN Primary IP Access from the LAN Zone
• Enabling Bandwidth Management on an Access Rule

Enabling Ping

This section provides a configuration example for an access rule to allow devices on the DMZ to send ping requests and receive ping responses from devices on the LAN. By default your SonicWALL security appliance does not allow traffic initiated from the DMZ to reach the LAN. Once you have placed one of your interfaces into the DMZ zone, then from the Firewall > Access Rules window, perform the following steps to configure an access rule that allow devices in the DMZ to send ping requests and receive ping responses from devices in the LAN.

1. Click Add to launch the Add Rule window.
2. Select the Allow radio button.
3. From the Service menu, select Ping.
4. From the Source menu, select DMZ Subnets.
5. From the Destination menu, select LAN Subnets.
6. Click OK.

Blocking LAN Access for Specific Services

This section provides a configuration example for an access rule blocking LAN access to NNTP servers on the Internet during business hours.

Perform the following steps to configure an access rule blocking LAN access to NNTP servers based on a schedule:

1. Click Add to launch the Add window.
2. Select Deny from the Action settings.
3. Select NNTP from the Service menu. If the service is not listed in the list, you must to add it in the Add Service window.
4. Select Any from the Source menu.
5. Select WAN from the Destination menu.
6. Select the schedule from the Schedule menu.
7. Enter any comments in the Comment field.
8. Click Add.

Allowing WAN Primary IP Access from the LAN Zone

By creating an access rule, it is possible to allow access to a management IP address in one zone from a different zone on the same SonicWALL appliance. For example, you can allow HTTP/HTTPS management or ping to the WAN IP address from the LAN side. To do this, you must create an access rule to allow the relevant service between the zones, giving one or more explicit management IP addresses as the destination. Alternatively, you can provide an address group that includes single or multiple management addresses (e.g. WAN Primary IP, All WAN IP, All X1 Management IP) as the destination. This type of rule allows the HTTP Management, HTTPS Management, SSH Management, Ping, and SNMP services between zones.

Note: Access rules can only be set for inter-zone management. Intra-zone management is controlled per-interface by settings in the interface configuration

To create a rule that allows access to the WAN Primary IP from the LAN zone:

1. On the Firewall > Access Rules page, display the LAN > WAN access rules.
2. Click Add to launch the Add window.
3. Select Allow from the Action settings.
4. Select one of the following services from the Service menu:
• HTTP
• HTTPS
• SSH Management
• Ping
• SNMP
5. Select Any from the Source menu.
6. Select an address group or address object containing one or more explicit WAN IP addresses from the Destination menu.

Note: Do not select an address group or object representing a subnet, such as WAN Primary Subnet. This would allow access to devices on the WAN subnet (already allowed by default), but not to the WAN management IP address.

7. Select the user or group to have access from the Users Allowed menu.
8. Select the schedule from the Schedule menu.
9. Enter any comments in the Comment field.
10. Click Add.

Enabling Bandwidth Management on an Access Rule

Bandwidth management can be applied on both ingress and egress traffic using access rules. Access rules displaying the Funnel icon are configured for bandwidth management.

Tip: Do not configure bandwidth management on multiple interfaces on a zone, where the configured guaranteed bandwidth for the zone is greater than the available bandwidth for the bound interface.

For more information on Bandwidth Management see Firewall Settings > BWM.