PA is dropping SYN packet with ECN and CWR

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L3 Networker

PA is dropping SYN packet with ECN and CWR

Hi Team, @reaper , @BPry 

 

Recently I have come across a scenario that palo alto was dropping TCP SYN packets which have ECN and CWR bits set. upon checking the global counter, i have seen that the drop reason was 'process owner message err, no predict'. anybody have seen this?. PA doesn't support SYN packets with ECN and CWR set ?..

 

Once I disable this enhancement in windows using the command 'netsh int tcp set global ecncapability=disabled', the session is getting established and the thinks are working fine.

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Community Manager

Re: PA is dropping SYN packet with ECN and CWR

I would expect these bits to either be stripped or ignored The global counter would indicate the session behavior has changed so it is trying to piggyback off another session for which there is no predict session set up I'd reach out to TAC to have this investigated

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