Delve deep into DNSSEC
BIND 9.10 is the new version of the BIND 9 DNS server from ISC http://isc.org (not to confuse with BIND 10, which is a different DNS server product). I will report in a series of articles about the new features in BIND 9.10. The first beta version of BIND 9.10 has been released this week and can be found at ftp://ftp.isc.org/isc/bind9/9.10.0b1/.
BIND 9.10 contains a new command-line tool to test DNSSEC
installations. The tool is called delve
and it works very much like
the already know dig
. It is like dig
with special DNSSEC
validation powers.
delve
checks the DNSSEC validation chain using the same code that is
used by the BIND 9 DNS server itself. Compared with the DNSSEC testing
function in dig +sigchase
, delve
is much closer to what really
happen inside a DNS server.
1.1 A simple lookup
shell> delve dnsworkshop.org ; fully validated dnsworkshop.org. 3600 IN A 91.190.147.212 dnsworkshop.org. 3600 IN RRSIG A 8 2 3600 20140318181408 20140216173922 63654 dnsworkshop.org. qS9/slk/jvcMc7+HSTMFD1D7GfuW5LIgBj0J1vCCCP5X+g9puhDdRSMM dURzelY6wsPVaUgtx44azEoJYHmNwFJlSsALPnekC6DWjKYMhzYilpUl OKAIZQh5lZxs3oimZHe6GEpEfkZ3ZV0IDTLLe4pIKRXoxDQ2eRJ543GD iTk=
Without extra arguments, delve
will query the local DNS server (taken
from /etc/resolv.conf
) for an IPv4-Address record at the given domain
name. It tries to validate the answer received, prints the result of the
validation, the requested data and the RRSIG Record (DNSSEC signature)
used to verify the data.
1.2 pretty-printing
As with dig
, resource record types and network classes can be given in
almost any order on the commandline. The switch +multi
(for multiline)
enables pretty printing; human readable output that is nearly
formatted for a 78 column screen.
shell> delve 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. O8mmiuNdXIWG6huaLiQrvKabDY3qivQ3R5qRUZ1IG3wp bd0UBnvpazpG01ntk8uZ7wEStScmiY7oYtvRGIHG37mG 8GFI60CUx3pdXJIpmodfoUBk8cfGsJXFQODIZCTUQiyk Pv9I6+wjyseDJJTYlrsBCvAEabPExFKZc7v+L+k= )
and IPv6
shell> delve 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. gqkc1Xq/UveKrhcXpqOwDsN5HFSqMsPkxXOyCqu9bMyx dtnkh0J0Iqukv+uHL/dDQLnPcxjdFqs3N5Jf3BFHdgkG tf0UPhNKsuhlsRdo2H5O+TqmLvA1zCsYhH/72vVvxslR MiiuZ1ILGpLA2EOyiZu70/ZIU3Ypc3nb8+ydgx4= )
1.3 tracing DNSSEC validation
delve
comes with a set of trace switches that can help
troubleshoot DNSSEC validation issues. The first switch, +rtrace
,
prints the extra DNS lookups delve
performs to validate the answer:
delve 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. hCOcPJrDCXpcVS82FgGEdUhaUmW3XkxXEuEa4AFvzkzi mDcokYNjrW/Hay4NclSWV0jrBwrXABXik5dh7w7KsPkD WKhw/qVvkuiFCm+T5lb9OVkGQAuPhBOplbVgdbZce9L7 N2IVTQTLMECKfzCTfKeOtwupJAMPXCt/Xskd5o4= )
In this example, in addition to the MX-Record (Mail-Exchanger) Record,
the DNSKEY record (DNSSEC public key) and the DS record (Delegation
signer) for dnsworkshop.org
, as well as the DNSKEY and DS records
for ORG
and the DNSKEY for the root-zone ".
" have been
requested. The trust-anchor for the Internet Root-Zone is compiled
into delve
and acts as the starting trust anchor for the validation.
The switch +mtrace
prints the content of any additional DNS records
that have been fetched for validation.
+vtrace
prints out the DNSSEC chain of validation:
shell> delve _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 ( 3E5E70BBA957CA0DAFCB799F15F6236133C0F6C73FA7 3762BFFBCA4AF92389CA ) _443._tcp.dnsworkshop.org. 3544 IN RRSIG TLSA 8 4 3600 ( 20140309145739 20140207135739 63654 dnsworkshop.org. JYkLiFqvrjqiIlm/bA4CaffJ3Iikos31bfEVb2njjIR+ /7dudq9pAj898OVZrtqIjmfD7knyCT2nt6Gp/yFYif4k Tt7W2XMhnWecwRnFexhVYp1zg2dkZSw4XcBRMz/F2NkM 0xziG9dNFg/6AAs/0ehMurLvRj1ula/UIO/wU5w= )
delve
is a very useful tool, not only for BIND 9 admins, but for
everyone who needs to troubleshoot and fix DNS- and DNSSEC related
issues.