dig

Table of Contents

1. Tools

I named this cheat dig because it's the most popular one, but this is umbrella for drill / nslookup / getent etc.

1.1. dig

# lookup
dig apple.com # A record
dig mx apple.com # mx record
dig +tcp -p 443 djh.im @208.67.220.220 # tcp, custom port, custom dns server(@)

# trace
dig +trace apple.com

1.2. drill

# lookup
drill -t -p 443 djh.im @208.67.220.220 # tcp, custom port, custom dns server(@)

# trace
drill -TD apple.com # w DNSSEC
drill -T apple.com # w/o DNSSEC
  • drill doesn't aim to be a 100% drop-in replacement for dig
    • drill -Q works similar to dig +short
    • Does not have +multiline like dig

1.2.1. Different records

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1.3. getent

getent hosts apple.com # get shit from /etc/hosts, this is what you'd get if you type the same in firefox
  • Gets you stuff from nsswitch, unlike dig/nslookup which query a dns nameserver.
  • This is what you want to see if you made changes to /etc/hosts

1.3.1. Hosts file format

  • The format is [ip_address] [hostname/domain] [alias], You can't put a domain in place(1st col) of the ip_address. System will simply ignore that.

2. Snippets

2.1. Public IP lookup

curl -fSs https://1.1.1.1/cdn-cgi/trace | awk -F= '/ip/ { print $2 }'

2.2. Finding services using TXT records

  • Some services use TXT records for domain validation
  • Now domain validation using txt records is debatable
    • Suggestion is to use opaque token and do linear search of all txt records on verification side instead of txt record value to be something like name=value_token
    • But using opaque token, as a webmaster you loose track of what that opaque token even refers to!

  • Just use drill txt stripe.com, Example. 

    ;; ->>HEADER<<- opcode: QUERY, rcode: NOERROR, id: 34543
;; flags: qr rd ra ; QUERY: 1, ANSWER: 20, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;; stripe.com.	IN	TXT

;; ANSWER SECTION:
stripe.com.	600	IN	TXT	"3l1wm9pqffwmrbvq2f5tbwjwtb8gjbr7"
stripe.com.	600	IN	TXT	"MS=ms80697640"
stripe.com.	600	IN	TXT	"apple-domain-verification=8kIS0gmJTvILWQuI"
stripe.com.	600	IN	TXT	"atlassian-domain-verification=upLp21qQgja1aHG2gnAb1AmXRqb/zG0UK1a0n3zTSXZg5DgOSttR3i5uzA3T9Cdk"
stripe.com.	600	IN	TXT	"docker-verification=ccde1a0d-8d2c-44b5-9d20-6c4e19113fc9"
stripe.com.	600	IN	TXT	"google-site-verification=PrlpJHdk11CIkPsiXoHEAJevWHAk39JRFAqVSe9l7n0"
stripe.com.	600	IN	TXT	"google-site-verification=ZgGi2-xDdfnaWxdfjn5AqtUS11jKWqSXAV_EHODFzdE"

2.3. See all the records examples!

See (All) DNS Resource Records 

# drill -Q <record_name> <record_name>.dns.netmeister.org.
# drill -Q txt <record_name>.dns.netmeister.org.
# eg.
drill -Q a a.dns.netmeister.org.
drill -Q txt a.dns.netmeister.org. # 2 txt recs

Created: 2024-07-16 Tue 16:44

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