Firewall settings

The Firewall module provides bidirectional stateful firewall protection. It prevents denial of service attacks and provides coverage for all IP-based protocols and frame types as well as filtering for ports and IP and MAC addresses.

The Firewall section of the Computer or Policy editorYou can change these settings for a policy or for a specific computer. To change the settings for a policy, go to the Polices page and double-click the policy that you want to edit (or select the policy and click Details). To change the settings for a computer, go to the Computers page and double-click the computer that you want to edit (or select the computer and click Details). has the following tabbed sections:

This article includes references to the Deep Security Virtual Appliance, which is not available with Deep Security as a Service.

General

Firewall

You can configure this Policy or Computer to inherit its Firewall On/Off state from its parent Policy or you can lock the setting locally.

Firewall Stateful Configurations

Select which Firewall Stateful Configuration to apply to this Policy. If you have defined multiple Interfaces for this Policy (above), you can specify independent configurations for each interface.

Assigned Firewall Rules

Displays the firewall Rules that are in effect for this Policy or computer. To add or remove Firewall Rules, click Assign/Unassign This will display a window showing all available Firewall Rules from which you can select or deselect Rules.

From a Computer or Policy editorYou can change these settings for a policy or for a specific computer. To change the settings for a policy, go to the Polices page and double-click the policy that you want to edit (or select the policy and click Details). To change the settings for a computer, go to the Computers page and double-click the computer that you want to edit (or select the computer and click Details). window, you can edit a Firewall Rule so that your changes apply only locally in the context of your editor, or you can edit the Rule so that the changes apply globally to all other Policies and Computers that are using the Rule.

To edit the Rule locally, select the Rule and click Properties () or right-click the Rule and click Properties.

To edit the Rule globally, right-click the Rule and click Properties (Global).

Interface Isolation

Interface Isolation

You can configure this Policy or Computer to inherit its Interface Isolation enabled or disabled state from its parent Policy or you can lock the setting locally.

Before you enable Interface Isolation make sure that you have configured the interface patterns in the proper order and that you have removed or added all necessary string patterns. Only interfaces matching the highest priority pattern will be permitted to transmit traffic. Other interfaces (which match any of the remaining patterns on the list) will be "restricted". Restricted Interfaces will block all traffic unless an Allow Firewall Rule is used to allow specific traffic to pass through.

Interface Patterns

When Interface Isolation is enabled, the firewall will try to match the regular expression patterns to interface names on the local computer.

Deep Security uses POSIX basic regular expressions to match interface names. For information on basic POSIX regular expressions, see
http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap09.html#tag_09_03

Only interfaces matching the highest priority pattern will be permitted to transmit traffic. Other interfaces (which match any of the remaining patterns on the list) will be "restricted". Restricted Interfaces will block all traffic unless an Allow Firewall Rule is used to allow specific traffic to pass through.

Selecting Limit to one active interface will restrict traffic to only a single interface (even if more than one interface matches the highest priority pattern).

Reconnaissance

Reconnaissance Scans

The Reconnaissance page allows you to enable and configure traffic analysis settings on your computers. This feature can detect possible reconnaissance scans that attackers often use to discover weaknesses before beginning a targeted attack.

  • Reconnaissance Scan Detection Enabled: Turn the ability to detect reconnaissance scans on or off.
  • Computers/Networks on which to perform detection: Choose from the list the IPs to protect. Choose from existing IP Lists. (You can use the Policies > Common Objects > Lists > IP Lists page to create an IP List specifically for this purpose.)
  • Do not perform detection on traffic coming from: Select from a set of IP Lists which computers and networks to ignore. (As above, you can use the Policies > Common Objects > Lists > IP Lists page to create an IP List specifically for this purpose.)

For each type of attack, the agent or applianceThe Deep Securty Agent and Deep Security Virtual Appliance are the components that enforce the Deep Security policies that you have defined. Agents are deployed directly on a computer. Appliances are used in VMware vSphere environments to provide agentless protection. They are not available with Deep Security as a Service. can be instructed to send the information to the Deep Security Manager where an Alert will be triggered. You can configure the Manager to send an email notification when the Alerts are triggered. (See Administration > System Settings > Alerts. The Alerts are: "Network or Port Scan Detected", "Computer OS Fingerprint Probe Detected", "TCP Null Scan Detected", "TCP FIN Scan Detected", and "TCP Xmas Scan Detected.") Select Notify DSM Immediately for this option.

For the "Notify DSM Immediately" option to work, the agents and appliances must be configured for agent or appliance-initiated or bidirectional communication in Computer or Policy editorYou can change these settings for a policy or for a specific computer. To change the settings for a policy, go to the Polices page and double-click the policy that you want to edit (or select the policy and click Details). To change the settings for a computer, go to the Computers page and double-click the computer that you want to edit (or select the computer and click Details). > Settings > General.) If enabled, the agent or appliance will initiate a heartbeat to the Deep Security Manager immediately upon detecting the attack or probe.

Once an attack has been detected, you can instruct the agents and appliances to block traffic from the source IPs for a period of time. Use the Block Traffic lists to set the number of minutes.

  • Computer OS Fingerprint Probe: The agent or appliance detects an attempt to discover the computers OS.
  • Network or Port Scan: The agent or appliance reports a network or port scan if it detects that a remote IP is visiting an abnormal ratio of IPs to ports. Normally, an agent or appliance computer will only see traffic destined for itself, so a port scan is the most common type of probe that will be detected. The statistical analysis method used in computer or port scan detection is derived from the "TAPS" algorithm proposed in the paper "Connectionless Port Scan Detection on the Backbone" presented at IPCCC in 2006.
  • TCP Null Scan: The agent or appliance detects packages with no flags set.
  • TCP SYNFIN Scan: The agent or appliance detects packets with only the SYN and FIN flags set.
  • TCP Xmas Scan: The agent or appliance detects packets with only the FIN, URG, and PSH flags set or a value of 0xFF (every possible flag set).
"Network or Port Scans" differs from the other types of reconnaissance in that it cannot be recognized by a single packet and requires Deep Security to watch traffic for a period of time.
The agent or appliance reports a computer or port scan if it detects that a remote IP is visiting an abnormal ratio of IPs to ports. Normally an agent or apppliance computer will only see traffic destined for itself, so a port scan is by far the most common type of probe that will be detected. However, if a computer is acting as a router or bridge it could see traffic destined for a number of other computers, making it possible for the agent or appliance to detect a computer scan (ex. scanning a whole subnet for computers with port 80 open).
Detecting these scans can take several seconds since the agent or appliance needs to be able to track failed connections and decide that there are an abnormal number of failed connections coming from a single computer in a relatively short period of time.
Deep Security Agents running on Windows computers with browser applications may occasionally report false-positive reconnaissance scans due to residual traffic arriving from closed connections.

For information on how to handle reconnaissance warnings, see Warning: Reconnaissance Detected.

Advanced

Events

Set whether to generate Events for packets that are "Out of Allowed Policy". These are packets that have been blocked because they have not been specifically allowed by an Allow Firewall Rule. Setting this option to Yes may generate a large number of Events depending the Firewall Rules you have in effect.

Events

Firewall Events are displayed the same way as they are in the main Deep Security Manager window except that only Events relating to this Policy or specific computer are displayed.