Bug ID 554444: LTM Policy resets connection when removing non-existant HTTP header

Last Modified: Nov 07, 2022

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

Known Affected Versions:
11.4.1, 11.5.0, 11.5.1, 11.5.1 HF1, 11.5.1 HF10, 11.5.1 HF11, 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, 11.5.10, 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, 11.6.0, 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, 12.0.0 HF3, 12.0.0 HF4

Fixed In:
12.1.0

Opened: Oct 26, 2015

Severity: 4-Minor

Symptoms

Customer might notice that certain HTTP requests would be prematurely terminated without seeing a response.

Impact

The connection gets reset, client does not see response.

Conditions

This occurs when an LTM Policy is defined to remove an HTTP header from a request or response, but the request or response does not contain the specified header.

Workaround

As a possible mitigation, if the HTTP header to be removed has narrowly-defined expected value, it may be possible to add a condition that effectively tests for the existence of a header. For example, instead of unconditionally removing the Server: header from a response, a condition could be added to check whether the Server: header contains "Apache", or even if it contains the letter 'a', or even any letter or number.

Fix Information

When removing HTTP headers from a request or a response, LTM Policy no longer treats a missing header as an error, and no longer resets the connection as a consequence.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips