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[EOL/EOS] What is the Policy check sequence for a packet?



Article ID: KB7821 KB Last Updated: 31 Mar 2021Version: 4.0
Note: A product listed in this article has either reached hardware End of Life (EOL) OR software End of Engineering (EOE).  Refer to End of Life Products & Milestones for the EOL, EOE, and End of Support (EOS) dates.

Packets denied by global policy

Customer is unable to send packets from one interface to another, although both of the interfaces are in the same zone with intra-zone block turned off.  In addition,  a global deny policy has been defined on the ScreenOS device.


The Policy look-up sequence for a packet is:

Step 1. Look for a policy between the ingress and egress zones
Step 2. If no policy is found (in step 1), search for a Global policy
Step 3. If no Global policy  is found and if the ingress zone is same as the egress zone, apply the intra-zone block
    i.e if intra-zone block is enabled, drop the packet otherwise permit.

In summary,  if there is no intra-zone policy and there is a Global DENY policy, whether intra-zone block is enabled or not, the ScreenOS device will match the Global policy and drop the packet.

To allow such traffic, define an intra-zone policy.

Modification History:
Article is reviewed for accuracy
03/27/2021 - Replaced term NetScreen with ScreenOS 
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