The last default rule on a firewall is to:
Deep Security 10.3 has reached end of support. Use the version selector (above) to see more recent versions of the Help Center. Show
In this article:
Firewall rule actionsFirewall rules can take the following actions:
More about Allow rulesAllow rules have two functions:
Traffic that is not explicitly allowed by an Allow rule is dropped, and gets recorded as an 'Out of "Allowed" Policy' firewall event. Commonly applied Allow rules include:
More about Bypass rulesThe Bypass rule is designed for media-intensive protocols or for traffic originating from trusted sources where filtering by the firewall or intrusion prevention modules is neither required nor desired. A packet that matches the conditions of a Bypass rule:
Since stateful inspection is not applied to bypassed traffic, bypassing traffic in one direction does not automatically bypass the response in the other direction. Bypass rules should always be created and applied in pairs, one rule for incoming traffic and another for outgoing. Bypass rule events are not recorded. This is not a configurable behavior. If the Deep Security Manager uses a remote database that is protected by a Deep Security Agent, intrusion prevention-related false alarms may occur when the Deep Security Manager saves intrusion prevention rules to the database. The contents of the rules themselves could be misidentified as an attack. One of the workarounds for this is to create a bypass rule for traffic from the Deep Security Manager to the database host. Default Bypass rule for Deep Security Manager trafficThe Deep Security Manager automatically implements a priority 4 Bypass rule that opens incoming TCP traffic on the agent's listening port for heartbeats (see Configure the heartbeat) on computers running Deep Security Agent. Priority 4 ensures that this rule is applied before any Deny rules, and Bypass guarantees that the traffic is never impaired. The Bypass rule is not explicitly shown in the firewall rule list because the rule is created internally. This rule, however, accepts traffic from any IP address and any MAC address. To harden the agent's security on this port, you can create an alternative, more restrictive bypass rule for this port. The agent will actually disable the default Deep Security Manager traffic rule in favor of the new custom rule provided it has these characteristics:
The custom rule must use the above parameters to replace the default rule. Ideally, the IP address or MAC address of the actual Deep Security Manager should be used as the packet source for the rule. More about Force Allow rulesThe Force Allow option excludes a sub-set of traffic that could otherwise have been covered by a Deny action. Its relationship to other actions is illustrated below. Force Allow has the same effect as a Bypass rule. However, unlike Bypass, traffic that passes the firewall because of this action is still subject to inspection by the intrusion prevention module. The Force Allow action is particularly useful for making sure that essential network services are able to communicate with the DSA computer. Generally, Force Allow rules should only be used in conjunction with Allow and rules to Allow a subset of traffic that has been prohibited by the Allow and Deny rules. Force Allow rules are also required to Allow unsolicited ICMP and UDP traffic when ICMP and UDP stateful are enabled. When using multiple Deep Security Managers in a multi-node arrangement, it may be useful to define an IP list for these servers, and then create a custom Deep Security Manager traffic rule with that list. Firewall rule sequencePackets arriving at a computer get processed first by firewall rules, then the firewall stateful configuration conditions, and finally by the intrusion prevention rules. This is the order in which firewall rules are applied (incoming and outgoing):
If you have no Allow rules in effect on a computer, all traffic is permitted unless it is specifically blocked by a Deny rule. Once you create a single Allow rule, all other traffic is blocked unless it meets the conditions of the Allow rule. There is one exception to this: ICMPv6 traffic is always permitted unless it is specifically blocked by a Deny rule. Within the same priority context, a Deny rule will override an Allow rule, and a Force Allow rule will override a Deny rule. By using the rule priorities system, a higher priority Deny rule can be made to override a lower priority Force Allow rule. Consider the example of a DNS server policy that makes use of a Force Allow rule to Allow all incoming DNS queries. Creating a Deny rule with a higher priority than the Force Allow rule lets you specify a particular range of IP addresses that must be prohibited from accessing the same public server. Priority-based rule sets allow you set the order in which the rules are applied. If a Deny rule is set with the highest priority, and there are no Force Allow rules with the same priority, then any packet matching the Deny rule is automatically dropped and the remaining rules are ignored. Conversely, if a Force Allow rule with the highest priority flag set exists, any incoming packets matching the Force Allow rule will be automatically allowed through without being checked against any other rules. A note on loggingBypass rules will never generate an event. This is not configurable. Log Only rules will only generate an event if the packet in question is not subsequently stopped by either:
If the packet is stopped by one of those two rules, those rules will generate the Event and not the Log Only rule. If no subsequent rules stop the packet, the Log Only rule will generate an event. How firewall rules work togetherDeep Security firewall rules have both a rule action and a rule priority. Used in conjunction, these two properties allow you to create very flexible and powerful rule-sets. Unlike rule-sets used by other firewalls, which may require that the rules be defined in the order in which they should be run, Deep Security Firewall rules are run in a deterministic order based on the rule action and the rule priority, which is independent of the order in which they are defined or assigned. Rule ActionEach rule can have one of four actions.
Implementing an Allow rule will cause all other traffic not specifically covered by the Allow rule to be denied:
A Deny rule can be implemented over an Allow to block specific types of traffic: A Force Allow rule can be placed over the denied traffic to Allow certain exceptions to pass through: Rule priorityRule actions of type Deny and Force Allow can be defined at any one of 5 priorities to allow further refinement of the permitted traffic defined by the set of Allow rules. Rules are run in priority order from highest (Priority 4) to lowest (Priority 0). Within a specific priority level the rules are processed in order based on the rule action (Force Allow, Deny, Allow, log only). The priority context Allows a User to successively refine traffic controls using Deny and Force Allow rule combinations. Within the same priority context, an Allow rule can be negated with a Deny rule, and a Deny rule can be negated by a Force Allow rule. Rule actions of type Allow run only at priority 0 while rule actions of type Log Only run only at priority 4. Putting rule action and priority togetherRules are run in priority order from highest (Priority 4) to lowest (Priority 0). Within a specific priority level the rules are processed in order based on the rule action. The order in which rules of equal priority are processed is as follows:
Remember that rule actions of type Allow run only at priority 0 while rule actions of type Log Only run only at priority 4. It is important to remember that if you have a Force Allow rule and a Deny rule at the same priority the Force Allow rule takes precedence over the Deny rule and therefore traffic matching the Force Allow rule will be permitted. What is the default rule for a firewall?When constructing a firewall, one of the fundamental decisions that you must make is the default policy. This determines what happens when traffic is not matched by any other rules. By default, a firewall can either accept any traffic unmatched by previous rules, or deny that traffic.
What are the rules of firewall?Firewall rules: Determine what traffic your firewall allows and what is blocked. Examine the control information in individual packets, and either block or allow them according to the criteria that you define. Control how the firewalls protect your network from malicious programs and unauthorized access.
What is default firewall blocking?By default, Windows Defender Firewall allows all outbound network traffic unless it matches a rule that prohibits the traffic. By default, Windows Defender Firewall block all inbound network traffic unless it matches a rule that allow the traffic.
What are the four basic types of firewall rules?Based on their method of operation, there are four different types of firewalls.. Packet Filtering Firewalls. Packet filtering firewalls are the oldest, most basic type of firewalls. ... . Circuit-Level Gateways. ... . Stateful Inspection Firewalls. ... . Application-Level Gateways (Proxy Firewalls). |