Dectyption Issue

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Dectyption Issue

L2 Linker

Dear Team!

I got a problem with Decryption on some websites. For example When I try to open this website, the web browser gives me a simple white blank without any content in it. In this case, decryption is on. I saw the error, depending on the certificate chain of trust, and I follow the documentation and imported the missing certificate to Firewall and then to the end user machine, but, not fixed.


This issue was in 10.1.7 and continues in 10.1.9 h2 I think. And, this problem the first time was faced while upgrading to 10.1.7.


Any ideas?



Community Team Member

Hi @RovshanRajabli ,


You might be running into bug behavior.

I've seen this exact same behaviour when http2 decrypted traffic was getting identified as unknown-tcp.  Please check if that's the case or if it is being identified correctly.


The root cause in my example was that each large http2 header holds a swbuf 4 until the end of the flow. This causes the swbuf 4 depletion.  You can check this with the following command as well:


admin@Lab> debug dataplane pool statistics | match "buffer 4"


As a workaround you could try to strip ALPN for the website that causes the buffer depletion.


That being said, I recommend grabbing a tech support file and have it analyzed by support in order to confirm if you are hitting this exact same bug or if you are experiencing a different issue.


Kind regards,


LIVEcommunity team member, CISSP
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Cyber Elite
Cyber Elite


Also some websites do not like it when you decrypt them. I know a lot of the Microsoft sites are like this and its best to bypass decryption on them.



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