[dns-operations] Spurious (?) DNSSEC SERVFAIL with some (?) versions of BIND for one domain?

Matthew Richardson matthew-l at itconsult.co.uk
Wed Mar 10 16:44:27 UTC 2021


Testing on two separate (but similarly configured) Bind 9.11.22 servers, I
also get SERVFAIL.  The logs show entries like:-

>10-Mar-2021 16:20:11.606 dnssec: info: validating _dmarc.prv.se/TXT: bad cache hit (_dmarc.prv.se/DS)

On a test machine running 9.11.8, and having cleared the cache beforehand,
SERVFAIL is returned with the same message logged.

Running tcpdump of the traffic from the Bind server, it gets the following
response back clearly showing NXDOMAIN with NSEC3 records:-

>Frame 106: 1081 bytes on wire (8648 bits), 1081 bytes captured (8648 bits)
>Ethernet II, Src: Xensourc_40:5c:c5 (00:16:3e:40:5c:c5), Dst: Xensourc_ec:56:8d (00:16:3e:ec:56:8d)
>Internet Protocol Version 4, Src: 80.80.64.49, Dst: 193.201.42.59
>Transmission Control Protocol, Src Port: 53, Dst Port: 33761, Seq: 1, Ack: 57, Len: 1027
>Domain Name System (response)
>    Length: 1025
>    Transaction ID: 0xf5c2
>    Flags: 0x8483 Standard query response, No such name
>        1... .... .... .... = Response: Message is a response
>        .000 0... .... .... = Opcode: Standard query (0)
>        .... .1.. .... .... = Authoritative: Server is an authority for domain
>        .... ..0. .... .... = Truncated: Message is not truncated
>        .... ...0 .... .... = Recursion desired: Don't do query recursively
>        .... .... 1... .... = Recursion available: Server can do recursive queries
>        .... .... .0.. .... = Z: reserved (0)
>        .... .... ..0. .... = Answer authenticated: Answer/authority portion was not authenticated by the server
>        .... .... ...0 .... = Non-authenticated data: Unacceptable
>        .... .... .... 0011 = Reply code: No such name (3)
>    Questions: 1
>    Answer RRs: 0
>    Authority RRs: 8
>    Additional RRs: 1
>    Queries
>        _dmarc.prv.se: type TXT, class IN
>            Name: _dmarc.prv.se
>            [Name Length: 13]
>            [Label Count: 3]
>            Type: TXT (Text strings) (16)
>            Class: IN (0x0001)
>    Authoritative nameservers
>        prv.se: type SOA, class IN, mname dns1.prv.se
>            Name: prv.se
>            Type: SOA (Start Of a zone of Authority) (6)
>            Class: IN (0x0001)
>            Time to live: 3600
>            Data length: 39
>            Primary name server: dns1.prv.se
>            Responsible authority's mailbox: postmaster
>            Serial Number: 2020111898
>            Refresh Interval: 1200 (20 minutes)
>            Retry Interval: 600 (10 minutes)
>            Expire limit: 1209600 (14 days)
>            Minimum TTL: 3600 (1 hour)
>        prv.se: type RRSIG, class IN
>            Name: prv.se
>            Type: RRSIG (46)
>            Class: IN (0x0001)
>            Time to live: 3600
>            Data length: 154
>            Type Covered: SOA (Start Of a zone of Authority) (6)
>            Algorithm: RSA/SHA-256 (8)
>            Labels: 2
>            Original TTL: 3600 (1 hour)
>            Signature Expiration: Mar 20, 2021 00:30:42.000000000 GMT Standard Time
>            Signature Inception: Mar  9, 2021 23:30:42.000000000 GMT Standard Time
>            Key Tag: 16321
>            Signer's name: prv.se
>            Signature: 65005703e9ddebaeeb4b3b9441b0eee96207c2ad7fd51e2c...
>        9qbq9dd8lt1gvge9gdmb5m0o13iuqeqt.prv.se: type NSEC3, class IN
>            Name: 9qbq9dd8lt1gvge9gdmb5m0o13iuqeqt.prv.se
>            Type: NSEC3 (50)
>            Class: IN (0x0001)
>            Time to live: 3600
>            Data length: 43
>            Hash algorithm: SHA-1 (1)
>            NSEC3 flags: 0
>                .... ...0 = NSEC3 Opt-out flag: Additional insecure delegations forbidden
>            NSEC3 iterations: 50
>            Salt length: 8
>            Salt value: 33e9285ab62c0803
>            Hash length: 20
>            Next hashed owner: 4f848f41f3884a3fc412e821e031cdd8b9a48eca
>            RR type in bit map: A (Host Address)
>            RR type in bit map: NS (authoritative Name Server)
>            RR type in bit map: SOA (Start Of a zone of Authority)
>            RR type in bit map: MX (Mail eXchange)
>            RR type in bit map: TXT (Text strings)
>            RR type in bit map: DS(Delegation Signer)
>            RR type in bit map: RRSIG
>            RR type in bit map: DNSKEY
>            RR type in bit map: NSEC3PARAM
>        9qbq9dd8lt1gvge9gdmb5m0o13iuqeqt.prv.se: type RRSIG, class IN
>            Name: 9qbq9dd8lt1gvge9gdmb5m0o13iuqeqt.prv.se
>            Type: RRSIG (46)
>            Class: IN (0x0001)
>            Time to live: 3600
>            Data length: 154
>            Type Covered: NSEC3 (50)
>            Algorithm: RSA/SHA-256 (8)
>            Labels: 3
>            Original TTL: 3600 (1 hour)
>            Signature Expiration: Mar 20, 2021 00:30:42.000000000 GMT Standard Time
>            Signature Inception: Mar  9, 2021 23:30:42.000000000 GMT Standard Time
>            Key Tag: 16321
>            Signer's name: prv.se
>            Signature: 65001128889870450779fe712fdb9bfe45144e0a881d6967...
>        lh8nso9jvk3fcgelcakjp266mb0vctj5.prv.se: type NSEC3, class IN
>            Name: lh8nso9jvk3fcgelcakjp266mb0vctj5.prv.se
>            Type: NSEC3 (50)
>            Class: IN (0x0001)
>            Time to live: 3600
>            Data length: 42
>            Hash algorithm: SHA-1 (1)
>            NSEC3 flags: 0
>                .... ...0 = NSEC3 Opt-out flag: Additional insecure delegations forbidden
>            NSEC3 iterations: 50
>            Salt length: 8
>            Salt value: 33e9285ab62c0803
>            Hash length: 20
>            Next hashed owner: d04ca2975f1127347e95613c06f83182d40d32c7
>            RR type in bit map: A (Host Address)
>            RR type in bit map: RRSIG
>        lh8nso9jvk3fcgelcakjp266mb0vctj5.prv.se: type RRSIG, class IN
>            Name: lh8nso9jvk3fcgelcakjp266mb0vctj5.prv.se
>            Type: RRSIG (46)
>            Class: IN (0x0001)
>            Time to live: 3600
>            Data length: 154
>            Type Covered: NSEC3 (50)
>            Algorithm: RSA/SHA-256 (8)
>            Labels: 3
>            Original TTL: 3600 (1 hour)
>            Signature Expiration: Mar 20, 2021 00:30:42.000000000 GMT Standard Time
>            Signature Inception: Mar  9, 2021 23:30:42.000000000 GMT Standard Time
>            Key Tag: 16321
>            Signer's name: prv.se
>            Signature: 65000f4e21423a299c9a10241de63d4fb67e210241c59d18...
>        hup1us667e5fsc26ltim32tpkio8r12b.prv.se: type NSEC3, class IN
>            Name: hup1us667e5fsc26ltim32tpkio8r12b.prv.se
>            Type: NSEC3 (50)
>            Class: IN (0x0001)
>            Time to live: 3600
>            Data length: 42
>            Hash algorithm: SHA-1 (1)
>            NSEC3 flags: 0
>                .... ...0 = NSEC3 Opt-out flag: Additional insecure delegations forbidden
>            NSEC3 iterations: 50
>            Salt length: 8
>            Salt value: 33e9285ab62c0803
>            Hash length: 20
>            Next hashed owner: 9881a5199e6882f827e451b26939f7c7b7441e6c
>            RR type in bit map: CNAME (Canonical NAME for an alias)
>            RR type in bit map: RRSIG
>        hup1us667e5fsc26ltim32tpkio8r12b.prv.se: type RRSIG, class IN
>            Name: hup1us667e5fsc26ltim32tpkio8r12b.prv.se
>            Type: RRSIG (46)
>            Class: IN (0x0001)
>            Time to live: 3600
>            Data length: 154
>            Type Covered: NSEC3 (50)
>            Algorithm: RSA/SHA-256 (8)
>            Labels: 3
>            Original TTL: 3600 (1 hour)
>            Signature Expiration: Mar 20, 2021 00:30:42.000000000 GMT Standard Time
>            Signature Inception: Mar  9, 2021 23:30:42.000000000 GMT Standard Time
>            Key Tag: 16321
>            Signer's name: prv.se
>            Signature: 650037f68f37932e0d8d38be77c0536486ff521278470802...
>    Additional records
>        <Root>: type OPT
>            Name: <Root>
>            Type: OPT (41)
>            UDP payload size: 4000
>            Higher bits in extended RCODE: 0x00
>            EDNS0 version: 0
>            Z: 0x8000
>                1... .... .... .... = DO bit: Accepts DNSSEC security RRs
>                .000 0000 0000 0000 = Reserved: 0x0000
>            Data length: 0

Maybe there is something in the NSEC3 which Bind does not like.  Trying
Unbound gets NXDOMAIN.

Best wishes,
Matthew

 ------
>From: Stephane Bortzmeyer <bortzmeyer at nic.fr>
>To: dns-operations at lists.dns-oarc.net
>Cc: 
>Date: Wed, 10 Mar 2021 15:32:40 +0100
>Subject: [dns-operations] Spurious (?) DNSSEC SERVFAIL with some (?) versions of BIND for one domain?

>Some resolvers cannot resolve the DMARC record _dmarc.prv.se/TXT. They
>reply SERVFAIL (the correct answer is NXDOMAIN). Running with checking
>disabled solves the problem.
>
>I see nothing that explains this problem. Zonemaster and DNSviz do not
>see it either.
>
>RIPE Atlas probes show that some probes' resolvers have the problem:
>
>% blaeu-resolve -r 100 --displayvalidation  --type TXT _dmarc.prv.se
>[ERROR: NXDOMAIN] : 86 occurrences
>[ERROR: SERVFAIL] : 12 occurrences
>Test #29281287 done at 2021-03-10T14:28:09Z
>
>It seems limited to some (?) versions of BIND. All the other resolvers
>I tested are fine. Here, with BIND:
>
>
>; <<>> DiG 9.11.5-P4-5.1+deb10u2-Debian <<>> @192.168.1.1 TXT _dmarc.prv.se
>; (1 server found)
>;; global options: +cmd
>;; Got answer:
>;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 22448
>;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
>
>;; OPT PSEUDOSECTION:
>; EDNS: version: 0, flags: do; udp: 1232
>; COOKIE: a5d317b0ecd877372d40f20b6048d7eeb17f96fd42e1cd5b (good)
>;; QUESTION SECTION:
>;_dmarc.prv.se.		IN TXT
>
>;; Query time: 36 msec
>;; SERVER: 192.168.1.1#53(192.168.1.1)
>;; WHEN: Wed Mar 10 15:30:06 CET 2021
>;; MSG SIZE  rcvd: 70
>
>
>
>
>; <<>> DiG 9.11.5-P4-5.1+deb10u2-Debian <<>> +cd @192.168.1.1 TXT _dmarc.prv.se
>; (1 server found)
>;; global options: +cmd
>;; Got answer:
>;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 5521
>;; flags: qr rd ra cd; QUERY: 1, ANSWER: 0, AUTHORITY: 8, ADDITIONAL: 1
>
>;; OPT PSEUDOSECTION:
>; EDNS: version: 0, flags: do; udp: 1232
>; COOKIE: a202795cfd0e59e942562a706048d7f38ae88ad6b4988c85 (good)
>;; QUESTION SECTION:
>;_dmarc.prv.se.		IN TXT
>
>;; AUTHORITY SECTION:
>prv.se.			3243 IN	SOA dns1.prv.se. postmaster. (
>				2020111898 ; serial
>				1200       ; refresh (20 minutes)
>				600        ; retry (10 minutes)
>				1209600    ; expire (2 weeks)
>				3600       ; minimum (1 hour)
>				)
>prv.se.			3243 IN	RRSIG SOA 8 2 3600 (
>				20210320003042 20210309233042 16321 prv.se.
>				VwPp3euu60s7lEGw7uliB8Ktf9UeLEMufsLVoalKCZ8G
>				i6Y5SL6u045fT2S//XpNwFZoFaJER1JtlOo5s97utv9k
>				gi2PFNWQ6VtfcMpYLcuvwuQ0xdwBUWBnmit7n0diZRzB
>				1KMSvzs7ur/+KBeGNcqqd4D2pjvxwYIHadDoQLY= )
>9qbq9dd8lt1gvge9gdmb5m0o13iuqeqt.prv.se. 3243 IN RRSIG NSEC3 8 3 3600 (
>				20210320003042 20210309233042 16321 prv.se.
>				ESiImHBFB3n+cS/bm/5FFE4KiB1pZ3norVyytnXdd4pv
>				LrtnJyhXcdgipneyozq2+0c1iwzaLUzLFKnC8yeIjvXB
>				pB6JQwFXYNOQXjnZOB30nX/PU3hfrgGuODJrjargXkCl
>				69sUaYMwK+uW2J3NAofjFOMizAK7by1bWCe9b3Q= )
>9qbq9dd8lt1gvge9gdmb5m0o13iuqeqt.prv.se. 3243 IN NSEC3 1 0 50 33E9285AB62C0803 (
>				9U28UGFJH153VH0IT0GU0CEDR2SQ93MA
>				A NS SOA MX TXT DS RRSIG DNSKEY NSEC3PARAM )
>hup1us667e5fsc26ltim32tpkio8r12b.prv.se. 3243 IN RRSIG NSEC3 8 3 3600 (
>				20210320003042 20210309233042 16321 prv.se.
>				N/aPN5MuDY04vnfAU2SG/1ISeEcIAnpd6F6ufX4uwMrx
>				J/R/FP+fzp0mn3zuseu124aMFBzX8SG9rRDt1keVmCaH
>				9rqooFuPZvbCr2WKmTi9OAWIzJSOzVcfimNnrNNU0J5C
>				By7dkt0umlzoKt73S9M0dVdjkoSUwxsyt9kYtos= )
>hup1us667e5fsc26ltim32tpkio8r12b.prv.se. 3243 IN NSEC3 1 0 50 33E9285AB62C0803 (
>				J20QA6CUD21FG9V4A6P6IEFNOURK87JC
>				CNAME RRSIG )
>lh8nso9jvk3fcgelcakjp266mb0vctj5.prv.se. 3243 IN RRSIG NSEC3 8 3 3600 (
>				20210320003042 20210309233042 16321 prv.se.
>				D04hQjopnJoQJB3mPU+2fiECQcWdGDKpADFdbYF0SvYK
>				B2WbMgOdHV3aOTSnkNnWX0QDTyarJ8JWpIQnq1wfaAbD
>				n7AlF3eOWYWNolClRIchvY4dIBwBbYVHLRQ6f/Hul1ww
>				D17xe6SmUOaLGyYNlLrXSuYHHRAeGY/XwZLNTlc= )
>lh8nso9jvk3fcgelcakjp266mb0vctj5.prv.se. 3243 IN NSEC3 1 0 50 33E9285AB62C0803 (
>				Q16A55QV24JJ8VKLC4U0DU1HGBA0QCM7
>				A RRSIG )
>
>;; Query time: 3 msec
>;; SERVER: 192.168.1.1#53(192.168.1.1)
>;; WHEN: Wed Mar 10 15:30:11 CET 2021
>;; MSG SIZE  rcvd: 1047
>
>
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