Bug ID 598874: GTM Resolver sends FIN after SYN retransmission timeout

Last Modified: Sep 13, 2023

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

Known Affected Versions:
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 HF1, 11.5.3 HF1, 11.5.3 HF2, 11.5.4 HF1, 11.5.4 HF2, 11.2.1, 11.4.1, 11.6.0, 11.6.1, 11.6.2, 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, 12.1.0 HF1, 12.0.0 HF2, 12.1.0 HF2, 12.0.0 HF3, 12.0.0 HF4, 12.1.1 HF1, 12.1.1 HF2, 12.1.2 HF1, 12.1.2 HF2, 12.1.0, 12.1.1

Fixed In:
13.0.0, 12.1.2, 11.6.1 HF2, 11.5.4 HF3

Opened: Jun 13, 2016

Severity: 3-Major

Symptoms

If a DNS server is not responding to TCP SYN, GTM Resolver sends a FIN after a retransmission timeout (RTO) of the SYN.

Impact

Firewalls may log the FIN as a possible attack.

Conditions

GTM Resolver tries to open a TCP connection to a server that does not respond.

Workaround

None

Fix Information

Do not send anything in response to a SYN retransmission timeout.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips