Bug ID 442139: Some iRules can result in stuck UDP connections

Last Modified: Apr 28, 2025

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

Known Affected Versions:
11.3.0, 11.4.0, 11.4.1, 11.5.0, 11.5.1, 11.5.1 HF1, 11.5.1 HF2, 11.5.1 HF3, 11.5.1 HF4, 11.5.1 HF5, 11.5.1 HF6, 11.5.1 HF7, 11.5.1 HF8, 11.5.1 HF9, 11.5.1 HF10, 11.5.1 HF11, 11.5.2, 11.5.2 HF1, 11.5.3, 11.5.3 HF1, 11.5.3 HF2, 11.5.4, 11.5.4 HF1, 11.5.4 HF2, 11.5.4 HF3, 11.5.4 HF4, 11.5.5, 11.5.6, 11.5.7, 11.5.8, 11.5.9, 11.5.10, 11.6.0, 11.6.0 HF1, 11.6.0 HF2, 11.6.0 HF3, 11.6.0 HF4, 11.6.0 HF5, 11.6.0 HF6, 11.6.0 HF7, 11.6.0 HF8, 11.6.1, 11.6.1 HF1, 11.6.1 HF2, 11.6.2, 11.6.2 HF1, 11.6.3, 11.6.3.1, 11.6.3.2, 11.6.3.3, 11.6.3.4, 11.6.4, 11.6.5, 11.6.5.1, 11.6.5.2, 11.6.5.3, 12.0.0, 12.0.0 HF1, 12.0.0 HF2

Fixed In:
12.1.0, 12.0.0 HF3, 11.4.1 HF9, 11.3.0 HF9

Opened: Jan 03, 2014

Severity: 3-Major

Related Article: K15210

Symptoms

When using an iRule on a UDP virtual server, it is possible for a connection flow to get stuck and remain allocated until it times out. The connection flow will appear via the tmsh (using "tmsh sys conn show") but will no longer pass packets. As new packets arrive, the flow timeout will be extended causing an outage.

Impact

Incoming packets matching the stuck connection are dropped.

Conditions

The connection flow must be aborted (e.g. ICMP/Reachable received from serverside) while the iRule is parked due to an asynchronous command.

Workaround

The error can only be cleared if the connection is allowed to timeout or the tmm is restarted.

Fix Information

Aborted UDP connections with parked iRules will be cleaned up normally and no longer match incoming packets.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips