Tag Archives: dns

snippet

DNS Fun

calc

A calculator supporting addition, substraction, multiplication and division (respectively : ADD, SUB ,MUL, and DIV operations). More information here.

dig 2.8.add.calc.postel.org @dns.postel.org +short
0.10.0.0
dig 8.2.sub.calc.postel.org @dns.postel.org +short
0.6.0.0
dig 2.8.mul.calc.postel.org @dns.postel.org +short
0.16.0.0
dig 8.2.div.calc.postel.org @dns.postel.org +short
0.4.0.0

IP to ASN Mapping

A service providing a way to map IPv4 and IPv6 addresses or prefixs to ASNs, get information about ASNs, and even find possible peers. More details here.

Mapping an IP address or prefix to a corresponding BGP Origin ASN:

dig 4.4.8.8.origin.asn.cymru.com TXT +short
"15169 | 8.8.4.0/24 | US | arin |"
dig 4.8.8.origin.asn.cymru.com TXT +short
"15169 | 8.8.4.0/24 | US | arin |"
dig 4.4.8.8.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.6.8.4.0.6.8.4.1.0.0.2.origin6.asn.cymru.com TXT +short
"15169 | 2001:4860::/32 | US | arin | 2005-03-14"

Getting information about a given ASN:

dig AS15169.asn.cymru.com TXT +short
"15169 | US | arin | 2000-03-30 | GOOGLE - Google Inc.,US"

fun

dig any google-public-dns-a.google.com +noall +answer
; <<>> DiG 9.8.3-P1 <<>> any google-public-dns-a.google.com +noall +answer
;; global options: +cmd
google-public-dns-a.google.com.	38271 IN TXT	"http://xkcd.com/1361/"
google-public-dns-a.google.com.	38271 IN AAAA	2001:4860:4860::8888
google-public-dns-a.google.com.	38271 IN A	8.8.8.8

more stuff at http://www.cambus.net/interesting-dns-hacks/

snippet

Get public IP using DNS

show public IP

Google:

dig o-o.myaddr.l.google.com txt @ns1.google.com +short
nslookup -type=txt o-o.myaddr.l.google.com ns1.google.com

"10.11.12.13"

OpenDNS:

dig myip.opendns.com @resolver1.opendns.com +short
nslookup myip.opendns.com resolver1.opendns.com

10.11.12.13

Akamai:

dig whoami.akamai.net. @ns1-1.akamaitech.net. +short
nslookup whoami.akamai.net. ns1-1.akamaitech.net.

10.11.12.13

other usage

dig o-o.myaddr.l.google.com txt
nslookup -type=txt o-o.myaddr.l.google.com

returns txt record of DNS request to authoritative source address
edns0-client-subnet if available, showing original DNS request source address

dig o-o.myaddr.l.google.com txt @8.8.8.8 +short
nslookup -type=txt o-o.myaddr.l.google.com 8.8.8.8

"198.51.100.1"
"edns0-client-subnet 203.0.113.0/24"