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Check Inbound and Outbound TCP Sequece Numbers on R80.20+

Incoming and outgoing TCP sequence numbers should not be changed at the Check Point firewall. I have always asked myself how this can be explained and I have come to the following solution!

This can be checked with the following one-liner:


fw ctl zdebug + packet |grep -A 5 "==I\|==O" |grep -B 5 '<IP-ADDRESS>' |grep "==I\|==O\|Device"


Change the <IP-ADDRESS> in the one-liner to your device.


Please note that "fw ctl zdebug" can cause performance problems on firewalls.

More see here:
"fw ctl zdebug" Helpful Command Combinations

1 Reply

The oneliner is a little different at R77.30.

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