Bug 1664863

Summary: [RFE] named: stale-answer support
Product: Red Hat Enterprise Linux 8 Reporter: Petr Menšík <pemensik>
Component: bindAssignee: Petr Menšík <pemensik>
Status: CLOSED ERRATA QA Contact: Robin Hack <rhack>
Severity: medium Docs Contact: Katerina Nemcova <knemcova>
Priority: high    
Version: 8.1CC: fkrska, pemensik, pmendezh, psklenar, redhat-bugzilla, rhack, thozza
Target Milestone: rcKeywords: FutureFeature, Reproducer
Target Release: 8.1   
Hardware: Unspecified   
OS: Unspecified   
Fixed In Version: bind-9.11.12-3.el8 Doc Type: Enhancement
Doc Text:
.`stale-answer` now provides old cached records in case of DDoS attack Previously, the Distributed Denial of Service (DDoS) attack caused the authoritative servers to fail with the SERVFAIL error. With this update, the `stale-answer` functionality provides the expired records until a fresh response is obtained. To enable or disable the `serve-stale` feature, use either of these: * Configuration file * Remote control channel (rndc)
Story Points: ---
Clone Of:
: 1769869 (view as bug list) Environment:
Last Closed: 2020-04-28 16:52:27 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On:    
Bug Blocks: Engineering1743192, Red Hat1755139, 1769869    

Description Petr Menšík 2019-01-09 21:16:54 UTC
Description of problem:
Support for stale-answer-enable and others is missing. Allows responding from cache when authoritative servers are under attack or not responding.

Upstream change:

4700. [func] Serving of stale answers is now supported. This

                        allows named to provide stale cached answers when
                        the authoritative server is under attack.
                        See max-stale-ttl, stale-answer-enable,
                        stale-answer-ttl. [RT #44790]

First commit:

Check bug #1653111 comment #7 for more details.

Version-Release number of selected component (if applicable):

Additional info:
Upstream has no support for stale cache in 9.11 ESV version, the feature was introduced in 9.12 version.

Comment 1 Petr Menšík 2019-01-09 21:30:32 UTC
Note: Serve-stale feature introduced also some defects fixed in 9.12.2-P1 release. It has to be included right away.


Comment 2 Petr Menšík 2019-08-29 09:40:50 UTC
Previous refractoring of resolver [1] makes backport hard. Not simple to check it is possible or not, have to decipher which changes would land where in the old code.

1. https://gitlab.isc.org/isc-projects/bind9/commit/96912e44b0b180de56f47d438f91c9e70925bd16

Comment 3 Petr Menšík 2019-08-29 19:30:58 UTC
Some working prototype was successful. More changes is required, but it seems possible into 9.11.

Comment 18 errata-xmlrpc 2020-04-28 16:52:27 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.