Create a Security Policy Rule
(Optional) Delete the default Security policy rule. By default, the firewall includes a security rule named rule1 that allows all traffic from Trust zone to Untrust zone. You can either delete the rule or modify the rule to reflect your zone naming conventions.
Add a rule. Select Policies > Security and click Add. Enter a descriptive Name for the rule in the General tab. Select a Rule Type.
Define the matching criteria for the source fields in the packet. In the Source tab, select a Source Zone. Specify a Source IP Address or leave the value set to any. Specify a Source User or leave the value set to any.
Define the matching criteria for the destination fields in the packet. In the Destination tab, set the Destination Zone. Specify a Destination IP Address or leave the value set to any. As a best practice, consider using address objects in the Destination Address field to enable access to specific servers or groups of servers only, particularly for services such as DNS and SMTP that are commonly exploited. By restricting users to specific destination server addresses you can prevent data exfiltration and command and control traffic from establishing communication through techniques such as DNS tunneling.
Specify the application the rule will allow or block. As a best practice, always use application-based security policy rules instead of port based rules and always set the Service to application-default unless you are using a more restrictive list of ports than the standard ports for an application. In the Applications tab, Add the Application to safely enable. You can select multiple applications, or use application groups or application filters. In the Service/URL Category tab, keep the Service set to application-default to ensure that any applications the rule allows are only allowed on their standard ports.
(Optional) Specify a URL category as match criteria for the rule. In the Service/URL Category tab, select the URL Category. If you select a URL category, only web traffic will match the rule and only if the traffic is to the specified category.
Define what action you want the firewall to take for traffic that matches the rule. In the Actions tab, select an Action. See Security Policy Actions for a description of each action.
Configure the log settings. By default, the rule is set to Log at Session End. You can clear this setting if you don’t want any logs generated when traffic matches this rule, or select Log at Session Start for more detailed logging. Select a Log Forwarding profile.
Attach security profiles to enable the firewall to scan all allowed traffic for threats. See Create Best Practice Security Profiles to learn how to create security profiles that protect your network from both known and unknown threats. In the Actions tab, select Profiles from the Profile Type drop-down and then select the individual security profiles to attach to the rule. Alternatively, select Group from the Profile Type drop-down and select a security Group Profile to attach.
Save the policy rule to the running configuration on the firewall. Click Commit.
To verify that you have set up your basic policies effectively, test whether your security policy rules are being evaluated and determine which security policy rule applies to a traffic flow. To verify the policy rule that matches a flow, use the following CLI command: test security-policy-match source <IP_address> destination <IP_address> destination port <port_number> protocol <protocol_number> The output displays the best rule that matches the source and destination IP address specified in the CLI command. For example, to verify the policy rule that will be applied for a server in the data center with the IP address when it accesses the Microsoft update server: test security-policy-match source destination destination-port 80 protocol 6 "Updates-DC to Internet" { from data_center_applications; source any; source-region any; to untrust; destination any; destination-region any; user any; category any; application/service[dns/tcp/any/53 dns/udp/any/53 dns/udp/any/5353 ms-update/tcp/any/80 ms-update/tcp/any/443]; action allow; terminal yes;

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