Bug ID 478994: NAT-T is configured but there is no NAT in the network, IPsec does not work.

Last Modified: Apr 10, 2019

Bug Tracker

Affected Product:  See more info
BIG-IP All(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

Fixed In:
12.0.0

Opened: Sep 11, 2014
Severity: 3-Major
Related AskF5 Article:
K17194

Symptoms

When NAT-T is ON in the IKE-peer configuration on the BIG-IP system, but there is no NATing in the network, IKE negotiation succeeds and brings up SAs correctly. But IPsec (ESP) packets will not pass because of a mismatch in the expected port number (4500 rather than 500) while receiving ESP packets.

Impact

IPsec packets are dropped and traffic loss.

Conditions

NAT_T is ON on the BIG-IP system and there is no NATing in the network.

Workaround

Do not configure NAT on the BIG-IP system if there is no NATing in the network.

Fix Information

NAT-T is configured but there is no NAT in the network, IPsec now works as expected.

Behavior Change