Dear Knot Resolver users,
Knot Resolver 5.6.0 has been released!
Security
- avoid excessive TCP reconnections in some cases (!1380)
For example, a DNS server that just closes connections without answer
could cause lots of work for the resolver (and itself, too).
The number of connections could be up to around 100 per client's query.
We thank Xiang Li from NISL Lab, Tsinghua University,
and Xuesong Bai and Qifan Zhang from DSP Lab, UCI.
Improvements
- daemon: feed server selection with more kinds of bad-answer events (!1380)
- cache.max_ttl(): lower the default from six days to one day
and apply both limits to the first uncached answer already (!1323 #127)
- depend on jemalloc, preferably, to improve memory usage (!1353)
- no longer accept DNS messages with trailing data (!1365)
- policy.STUB: avoid applying aggressive DNSSEC denial proofs (!1364)
- policy.STUB: avoid copying +dnssec flag from client to upstream (!1364)
Bugfixes
- policy.DEBUG_IF: don't print client's packet unconditionally (!1366)
Full changelog:
https://gitlab.nic.cz/knot/knot-resolver/raw/v5.6.0/NEWS
Sources:
https://secure.nic.cz/files/knot-resolver/knot-resolver-5.6.0.tar.xz
GPG signature:
https://secure.nic.cz/files/knot-resolver/knot-resolver-5.6.0.tar.xz.asc
Documentation:
https://knot-resolver.readthedocs.io/en/v5.6.0/
--
Ales Mrazek
PGP: 3057 EE9A 448F 362D 7420 5A77 9AB1 20DA 0A76 F6DE
Hello everyone,
at AS50242 we experience problem with resolving connectivity.samsung.com.cn
We run two servers, each with 4 instances. Both servers have working
dual-stack (v4/v6).
knot-dnsutils/unknown,now 3.1.1-cznic.1 amd64 [installed]
knot-resolver-module-http/unknown,now 5.5.0-cznic.1 all [installed,automatic]
knot-resolver-release/unknown,now 1.9-1 all [installed]
knot-resolver/unknown,now 5.5.0-cznic.1 amd64 [installed]
Dnsviz shows problem reaching few IPv6 servers of .cn TLD via UDP. I
can not understand, why both of our servers response with SERVFAIL.
Any ideas how to troubleshoot more?
Thank you,
Blažej
Hello,
I am a user, not a developer, of knot-resolver, on ubuntu groovy.
When I look up something that has a CNAME and ask for an A record I get
a SERVFAIL. If I ask for the CNAME I get the correct answer but then I
have to do another search for the A record for that.
#-------------
# using knot-resolver
kdig @127.0.53.1 www.cdc.gov.
;; ->>HEADER<<- opcode: QUERY; status: SERVFAIL; id: 44868
#-------------
# using google dns
kdig 8.8.8.8 www.cdc.gov.
www.cdc.gov. 126 IN CNAME www.akam.cdc.gov.
www.akam.cdc.gov. 20 IN A 104.100.61.241
#-------------
My guess is I don't have a complete configuration. Here's my very
simple knot-resolver.conf
#------------
-- SPDX-License-Identifier: CC0-1.0
-- Network interface configuration
net.listen('127.0.53.1')
-- Load useful modules
modules = {
'hints > iterate', -- Load /etc/hosts and allow custom root hints
'stats', -- Track internal statistics
'predict', -- Prefetch expiring/frequent records
}
-- Cache size
cache.size = 100 * MB
--
-- MY STUFF
--
internalDomains = policy.todnames({
'main',
'0.1.10.in-addr.arpa',
'1.10.in-addr.arpa',
'10.in-addr.arpa'
})
policy.add(policy.suffix(policy.FLAGS({'NO_CACHE'}), internalDomains))
policy.add(policy.suffix(policy.STUB({'127.53.0.1'}), internalDomains))
#-------------
How do I fix this?
Thank you,
Mike Wright
Hi,
i installed knot-resolver on my mail server and i see a issue with a specific domain, dovecot.org.
Everything is working as expected but this single domain doesn't always resolve.
After some time postfix cannot check the domain where mails coming from and doesn't accept them.
If i do dig dovecot.org, i get this (SERVFAIL):
dig dovecot.org
; <<>> DiG 9.11.26-RedHat-9.11.26-6.el8 <<>> dovecot.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 27594
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;dovecot.org. IN A
;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fr Apr 29 08:34:55 CEST 2022
;; MSG SIZE rcvd: 40
it starts working again if do dig +cd, like this:
dig +cd dovecot.org
; <<>> DiG 9.11.26-RedHat-9.11.26-6.el8 <<>> +cd dovecot.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 56130
;; flags: qr rd ra cd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;dovecot.org. IN A
;; ANSWER SECTION:
dovecot.org. 300 IN A 94.237.12.234
;; Query time: 245 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fr Apr 29 08:34:59 CEST 2022
;; MSG SIZE rcvd: 56
i didn't have this kind of issue using unbound before i switched, so i think here would be the right place to ask.
i'm using the knot-resolver 5.5.0 package from epel on rockylinux 8.5 and my kresd config is very simple:
net.listen('127.0.0.1', 53, { kind = 'dns' })
net.listen('127.0.0.1', 853, { kind = 'tls' })
--net.listen('127.0.0.1', 443, { kind = 'doh2' })
net.listen('::1', 53, { kind = 'dns', freebind = true })
net.listen('::1', 853, { kind = 'tls', freebind = true })
--net.listen('::1', 443, { kind = 'doh2' })
-- Load useful modules
modules = {
'hints > iterate', -- Allow loading /etc/hosts or custom root hints
'stats', -- Track internal statistics
'predict', -- Prefetch expiring/frequent records
}
-- Cache size
cache.size = 100 * MB
-- use /etc/hosts entries
-- hints.add_hosts()
net.ipv6 = false
Anything i can do to track this down?
Thanks in advance for your help.
Juergen
Hello,
I have noticed kresd segfault:
[Sun May 15 14:22:47 2022] kresd[1791403]: segfault at 407ce590 ip
00000000407ce590 sp 00007ffc2d192668 error 15
There were also about 1300 lines from the same PID with a message like this:
May 15 14:23:45 xxxx kresd[1791403]: [primin] triggered priming query,
next in 0 seconds
Maybe it is related to the crash maybe not.
OS: Debian Linux 11.3 kernel 5.10.0-13-amd64 #1 SMP Debian 5.10.106-1
(2022-03-17)
Knot-Resolver: 5.5.0-cznic.1
With regards
Ales