Bug ID 1972465: LTM Syncookie always SW mode for a wildcard virtual server

Last Modified: Oct 15, 2025

Affected Product(s):
BIG-IP LTM(all modules)

Known Affected Versions:
17.1.2.1, 17.1.2.2, 17.1.3

Opened: Jun 27, 2025

Severity: 3-Major

Symptoms

LTM Syncookie mode is stuck in software only for a virtual server.

Impact

One virtual server is in hardware SYN cookie mode, the other is in software SYN cookie mode.

Conditions

- LTM provisioned, no AFM - Two identical virtual servers listening on different VLANs - SYN flood on both virtuals

Workaround

tmsh modify sys db pvasyncookies.preferhwlmode value true reboot

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips