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Eleven, twelve; dig and delv: BIND 9.10

  • Updated on 26 Sep 2018
  • 3 minutes to read
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Surely you remember the old nursery rhyme that begins with "One, two, buckle my shoe." You might have forgotten that its sixth verse is "Eleven, twelve, dig and delve." How many nursery rhymes have their own Wikipedia page?

BIND 9.10 contains a new debugging tool that is a successor to dig. So, of course, we had to name it delv. It works very much like dig, but it understands DNSSEC better.

delv checks the DNSSEC validation chain using the same code that is used by the BIND 9 DNS server itself. Compared to  dig +sigchase, delv is much closer to what really happens inside a DNS server.

Like all BIND tools, delv is fully documented in Appendix B of the BIND ARM. In general, you should use delv the same way you have been using dig. But delv is not an enhanced version of dig; it is an entirely new program. So here are a few tips.

delv FQDN

If you just say delv name, and name is in a signed zone, delv will report "fully validated" and give you the RRSIG as part of the answer.

delv +multi

DNSSEC-related records are often very long. To make its output more readable, delv has a +multi option that formats large records into multiline reports that are readable in a standard 80-column text window. Men and Mice has provided this example of the use of +multi:

% delv dnsworkshop.org soa +multi
; fully validated
dnsworkshop.org.        3600 IN SOA ns1.myinfrastructure.org. hostmaster.strotmann.de. (
               86         ; serial
               86400      ; refresh (1 day)
               7200       ; retry (2 hours)
               3542400    ; expire (5 weeks 6 days)
               3600       ; minimum (1 hour)
dnsworkshop.org.        3600 IN RRSIG SOA 8 2 3600 (
               20140321030247 20140219020247 63654 dnsworkshop.org.
               Pv9I6+wjyseDJJTYlrsBCvAEabPExFKZc7v+L+k= )

Like dig, delv is fully compatible with IPv6:

% delv dnsworkshop.org AAAA +multi
; fully validated
dnsworkshop.org.        7200 IN AAAA 2001:470:1f08:f1d::2
dnsworkshop.org.        7200 IN RRSIG AAAA 8 2 7200 (
               20140321025727 20140219020247 63654 dnsworkshop.org.
               MiiuZ1ILGpLA2EOyiZu70/ZIU3Ypc3nb8+ydgx4= )

delv +multi +rtrace

The command delv +rtrace prints the extra DNS lookups that delv needs to make while validating the reply to a query. This example is from Men and Mice:

% delv dnsworkshop.org mx +multi +rtrace
;; fetch: dnsworkshop.org/MX
;; fetch: dnsworkshop.org/DNSKEY
;; fetch: dnsworkshop.org/DS
;; fetch: org/DNSKEY
;; fetch: org/DS
;; fetch: ./DNSKEY
; fully validated
dnsworkshop.org.        3600 IN MX 100 mail.strotmann.de.
dnsworkshop.org.        3600 IN RRSIG MX 8 2 3600 (
                                20140308193355 20140206183355 63654 dnsworkshop.org.
                                N2IVTQTLMECKfzCTfKeOtwupJAMPXCt/Xskd5o4= )``

delv +multi +vtrace

The +vtrace option shows the entire DNSSEC chain of validation. This example again from Men and Mice:

shell> delv _443._tcp.dnsworkshop.org TLSA  +multi +vtrace
;; fetch: _443._tcp.dnsworkshop.org/TLSA
;; validating _443._tcp.dnsworkshop.org/TLSA: starting
;; validating _443._tcp.dnsworkshop.org/TLSA: attempting positive response validation
;; fetch: dnsworkshop.org/DNSKEY
;; validating dnsworkshop.org/DNSKEY: starting
;; validating dnsworkshop.org/DNSKEY: attempting positive response validation
;; fetch: dnsworkshop.org/DS
;; validating dnsworkshop.org/DS: starting
;; validating dnsworkshop.org/DS: attempting positive response validation
;; fetch: org/DNSKEY
;; validating org/DNSKEY: starting
;; validating org/DNSKEY: attempting positive response validation
;; fetch: org/DS
;; validating org/DS: starting
;; validating org/DS: attempting positive response validation
;; fetch: ./DNSKEY
;; validating ./DNSKEY: starting
;; validating ./DNSKEY: attempting positive response validation
;; validating ./DNSKEY: verify rdataset (keyid=19036): success
;; validating ./DNSKEY: signed by trusted key; marking as secure
;; validating org/DS: in fetch_callback_validator
;; validating org/DS: keyset with trust secure
;; validating org/DS: resuming validate
;; validating org/DS: verify rdataset (keyid=33655): success
;; validating org/DS: marking as secure, noqname proof not needed
;; validating org/DNSKEY: in dsfetched
;; validating org/DNSKEY: dsset with trust secure
;; validating org/DNSKEY: verify rdataset (keyid=21366): success
;; validating org/DNSKEY: marking as secure (DS)
;; validating dnsworkshop.org/DS: in fetch_callback_validator
;; validating dnsworkshop.org/DS: keyset with trust secure
;; validating dnsworkshop.org/DS: resuming validate
;; validating dnsworkshop.org/DS: verify rdataset (keyid=24209): success
;; validating dnsworkshop.org/DS: marking as secure, noqname proof not needed
;; validating dnsworkshop.org/DNSKEY: in dsfetched
;; validating dnsworkshop.org/DNSKEY: dsset with trust secure
;; validating dnsworkshop.org/DNSKEY: verify rdataset (keyid=2611): success
;; validating dnsworkshop.org/DNSKEY: marking as secure (DS)
;; validating _443._tcp.dnsworkshop.org/TLSA: in fetch_callback_validator
;; validating _443._tcp.dnsworkshop.org/TLSA: keyset with trust secure
;; validating _443._tcp.dnsworkshop.org/TLSA: resuming validate
;; validating _443._tcp.dnsworkshop.org/TLSA: verify rdataset (keyid=63654): success
;; validating _443._tcp.dnsworkshop.org/TLSA: marking as secure, noqname proof not needed
; fully validated
_443._tcp.dnsworkshop.org. 3544 IN TLSA 3 0 1 (
                                3762BFFBCA4AF92389CA )
_443._tcp.dnsworkshop.org. 3544 IN RRSIG TLSA 8 4 3600 (
                                20140309145739 20140207135739 63654 dnsworkshop.org.
                                0xziG9dNFg/6AAs/0ehMurLvRj1ula/UIO/wU5w= )``
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