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[SRX] How to troubleshoot a security policy that is not passing data

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Article ID: KB10113 KB Last Updated: 28 Dec 2020Version: 10.0
Summary:
 

This article details how to troubleshoot a security policy that is not passing data.

 

Symptoms:
 

Traffic is not matching the expected security policy or traffic is getting denied.

 

Solution:
 

Use the following steps to troubleshoot a security policy that is not passing data:

  1. Is the security policy order correct? 

The ordering of security policies is important as the policy lookup process is performed from top to bottom until a match is found. Validate the order of the security policies with the command show security match policies. Refer to Understanding Security Policy Ordering for more information.

  1. Is the expected security policy configured correctly to match the traffic that is not passing?

Run the following command:

show security policies from-zone <zone> to-zone <zone> policy-name <policy> detail

(The detail parameter reports the address-book names and the corresponding IP address/subnet based on the configuration. This option is not available in J-Web.)

Example:

root@SiteA> show security policies from-zone trust to-zone untrust policy-name internal-net detail
Policy: internal-net, action-type: permit, State: enabled, Index: 4, Scope Policy: 0
  Policy Type: Configured
  Sequence number: 1
  From zone: trust, To zone: untrust
  Source addresses:
    internal-net: 10.20.20.0/24  
    local-net: 192.168.10.0/24   <------
  Destination addresses:
    remote-net: 192.168.20.0/24  <------
  Application: any               <------
    IP protocol: 0, ALG: 0, Inactivity timeout: 0
      Source port range: [0-0]
      Destination port range: [0-0]
  Per policy TCP Options: SYN check: No, SEQ check: No

  1. Verify that the "Source addresses" and "Destination addresses," including the subnet, are inclusive of the expected traffic source and destination IP addresses.

In our example, the source IP addresses in the subnet 192.168.10.0/24 will match the address-book entry local-net, and the destination IP addresses in the subnet 192.168.20.0/24 will match the address-book entry remote-net.

  1. Verify that the "Application" includes the expected applications.  

  2. Verify the "action-type."

  1. If NAT is configured, are the source and/or destination address translations correct? 

For assistance, consult:  KB21719 - How to check and interpret the Flow Sessions installed in the SRX when troubleshooting NAT.

  • Yes  - Continue to Step 4.

  • No   - Correct the addresses and try passing traffic again.

  1. Is traffic from the client reaching the SRX device? For assistance, set up traceoptions by using the instructions in KB16233 - Setting up security flow traceoptions and check whether the packets are being dropped by the SRX device.

  • Yes - If you are not able to determine the drop point, continue to Step 5.

  • No - Correct the network issue and try passing traffic again.

  1. Collect the logs specified in KB21781 - [SRX] Data Collection Checklist - Logs/data to collect for troubleshooting and open a case with your technical support representative.

 

Modification History:
 

2020-12-28: Minor changes made to the symptoms section; article checked for accuracy and found valid

 

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