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L0 Member


Good day All


i had read all the possible solution to this issue, but still presenting the same symphtom, i have applied all solutions mentioned on all posts.



does anyone had or did something different?


thanks in advance.

kind regards.


L4 Transporter

Hello The screenshot shows two packets sent, but no packet received. This is a tcp connection, hence a three-way-handshake (which includes one received packet) is mandatory for connection setup. Your data doesn't show any NAT entry. Do you have the NAT rule configured?
L0 Member

Good day


No, i don't have a NAT, because we use PA as webfilter, the main link is connected to another firewall and from there we connect to the PA.

the 'front' firewall is mainly to block external sites/attacks.



L4 Transporter

this looks like routing issue , palo alto identify application once it completes TCP 3 way handshake following data sent by server have any application data to perform pattern matching using signatures or for following destination cached entry is already stored in using APP ID cache.

You can try to filter using only destination IP and can see if application is identified earlier.


Run packet capture on firewall between source and destination to look for more detail.

SD-WAN | Cloud Networking | PCNSE | ICSI CNSS | MCNA | | CCNP | CCSA | SPSP | SPSX | F5-101 | CCIE-SEC-Attempted
Tags (1)
L3 Networker

Yes, PCAP at this point is the way to go. Most likely:


* SYN/ACK packet is never received by Palo or

* SYN/ACK packet is received by Palo but it does not know how to route that packet back to the destination 

L4 Transporter

Do the packets hit the upstream firewall?


As mentioned it's either a routing or filtering issue elsewhere, the traffic is not returning.




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