Bug ID 1121085: Some valid connections may get rejected in hardware SYN cookie mode

Last Modified: Jan 20, 2023

Bug Tracker

Affected Product:  See more info
BIG-IP TMOS(all modules)

Known Affected Versions:
14.1.0, 14.1.0.1, 14.1.0.2, 14.1.0.3, 14.1.0.5, 14.1.0.6, 14.1.2, 14.1.2.1, 14.1.2.2, 14.1.2.3, 14.1.2.4, 14.1.2.5, 14.1.2.6, 14.1.2.7, 14.1.2.8, 14.1.3, 14.1.3.1, 14.1.4, 14.1.4.1, 14.1.4.2, 14.1.4.3, 14.1.4.4, 14.1.4.5, 14.1.4.6, 14.1.5, 14.1.5.1, 14.1.5.2, 14.1.5.3, 15.1.0, 15.1.0.1, 15.1.0.2, 15.1.0.3, 15.1.0.4, 15.1.0.5, 15.1.1, 15.1.2, 15.1.2.1, 15.1.3, 15.1.3.1, 15.1.4, 15.1.4.1, 15.1.5, 15.1.5.1, 15.1.6, 15.1.6.1, 15.1.7, 15.1.8, 15.1.8.1

Opened: Jun 23, 2022
Severity: 3-Major

Symptoms

Due to an algorithm mismatch in software and hardware, valid TCP connections may get rejected with "No flow found for ACK' reset-cause when the hardware SYN cookie mode is active.

Impact

Service degradation.

Conditions

- BIG-IP iSeries appliances with ePVA support and the B2250 and B44xx VIPRION blades. - Hardware SYN cookie mode is activated.

Workaround

- Disable the hardware SYN cookie mode globally. - After a reboot, restart the TMM for an additional time.

Fix Information

None

Behavior Change