Bug ID 760550: Retransmitted TCP packet has FIN bit set

Last Modified: Nov 07, 2022

Bug Tracker

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

Known Affected Versions:
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, 12.1.0, 12.1.0 HF1, 12.1.0 HF2, 12.1.1, 12.1.1 HF1, 12.1.1 HF2, 12.1.2, 12.1.2 HF1, 12.1.2 HF2, 12.1.3, 12.1.3.1, 12.1.3.2, 12.1.3.3, 12.1.3.4, 12.1.3.5, 12.1.3.6, 12.1.3.7, 12.1.4, 12.1.4.1, 13.1.0, 13.1.0.1, 13.1.0.2, 13.1.0.3, 13.1.0.4, 13.1.0.5, 13.1.0.6, 13.1.0.7, 13.1.0.8, 13.1.1, 13.1.1.2, 13.1.1.3, 13.1.1.4, 13.1.1.5, 14.0.0, 14.0.0.1, 14.0.0.2, 14.0.0.3, 14.0.0.4, 14.0.0.5, 14.0.1, 14.1.0, 14.1.0.1, 14.1.0.2, 14.1.0.3, 14.1.0.5

Fixed In:
15.0.0, 14.1.0.6, 14.0.1.1, 13.1.3, 12.1.5, 11.6.5.1

Opened: Mar 06, 2019
Severity: 3-Major

Symptoms

After TCP sends a packet with FIN, retransmitted data earlier in the sequence space might also have the FIN bit set.

Impact

The retransmitted packet has the FIN bit set even if it does not contain the end of the data stream. This might cause the connection to stall near the end.

Conditions

-- Nagle is enabled. -- TCP has already sent a FIN. -- A packet is retransmitted with less than MSS bytes in the send queue.

Workaround

Set Nagle to disabled in the TCP profile.

Fix Information

The incorrect FIN bit is removed.

Behavior Change