Bug ID 606565: TMM may crash when /sys db tm.simultaneousopen is set to reset or drop_connection

Last Modified: Oct 06, 2020

Bug Tracker

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

Known Affected Versions:
12.1.0, 12.1.0 HF1, 12.1.0 HF2, 12.1.1, 12.1.1 HF1, 12.1.1 HF2

Fixed In:
13.0.0, 12.1.2

Opened: Jul 22, 2016
Severity: 3-Major
Related AskF5 Article:


When the /sys db tm.simultaneousopen variable is set to 'reset' or 'drop_connection', TMM may crash during a TCP simultaneous 4 way handshake.


Traffic disrupted while tmm restarts.


1. The /sys db tm.simultaneousopen variable is set to 'reset' or 'drop_connection'. 2. A TCP 4 way handshake (simultaneous open) occurs as described in RFC 793.


The crash can be avoided, while still mitigating TCP 4 way handshakes, by setting the /sys db tm.simultaneousopen variable to 'drop_pkt'.

Fix Information


Behavior Change