Firewall ruleset example

Firewall rulesets frequently have source address, source port, destination address, destination port, and whether the traffic should be allowed or denied.

For example, in this firewall ruleset example, the firewall is never directly accessed from the public network. If hackers can directly access the firewall, then they can modify or delete rules, and allow unwanted travel through.

Source address  Source port  Destination address  Destination port  Action 
Any  Any  Any  Deny 
Any  Any  Any  Deny  Any  Any  Any  Deny  Any  Any  Any  Deny 

And, in the following firewall ruleset example, all traffic from the trusted network is allowed out. But this ruleset should be placed below the ruleset above because the rules that impact the most traffic should be earlier in the list.

Source address  Source port  Destination address  Destination port  Action  Any  Any  Any  Allow 

FAQ about firewall rules

What are examples of best practices for some firewall rules?

Application protocols can use TCP, UDP, or both protocols. An application server typically listens on one or more fixed TCP or UDP ports. Deny by default policies should be used for incoming TCP and UDP traffic. Less strict policies are used for outgoing TCP and UDP traffic because most organizations allow users to access a wide range of external applications on millions of external hosts. Attackers can use ICMP types and codes to perform reconnaissance or manipulate the flow of network traffic. To prevent malicious activity, firewalls at the network’s perimeter should deny all incoming and outgoing ICMP traffic except for traffic explicitly permitted by the organization.

How do firewall policies differ from a network security policy?

network security policy sets out guidelines for computer access, determines enforcement, and lays out the architecture of the organization’s network security environment, and defines how the policies are implemented throughout the architecture.  However, firewall policies are just a small part of an organization’s overall network security policy. Firewall policies go into the specifics of what traffic is and isn’t permitted.  A firewall policy defines how an organization's firewalls should handle inbound and outbound network traffic for specific IP addresses and address ranges, protocols, applications, and content types based on the organization's network and information security policies. 

How do firewall rules relate to firewall settings?

Some firewalls implement policy through explicit rules, while others require configuring firewall settings that create internal rules. Some create policies and rules automatically while others use a combination of the above. At the end of the day, no matter how rules are created, you get a set of rules called a ruleset, describing how the firewall acts. 

See how AlgoSec can help manage your firewall rules as part of comprehensive network security policy management

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