IPS protection "TCP Off-Path Sequence Inference" drops TCP packets originated by Security Gateway

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Technical Level

Solution ID	sk104637
Technical Level
Product	IPS
Version	R77, R77.10, R77.20, R77.30
Platform / Model	All
Date Created	09-Feb-2015
Last Modified	30-May-2015

Symptoms

SmartView Tracker logs show that IPS protection "TCP Off-Path Sequence Inference" drops TCP packets originated by Security Gateway:

Blade: IPS
Action: Drop
Attack Name: Streaming Engine: TCP off-path sequence inference
Attack Information: TCP off-path sequence inference.
Protection Name: TCP off-path sequence inference
Protection ID: tcp_off_path_enable

SecureXL status (enabled / disabled) is not relevant.

Cause

IPS protection "TCP Off-Path Sequence Inference" drops TCP packets originated by Security Gateway that contain "ACK" number that was already accepted.

Solution

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