Finding ALL currently used IP / ASN addresses of Websites

You can do it reliably, but the list of IP addresses can and will change over time, so you have to do it again from time to time.

For blocking companies with lots of IP addresses, you first need to find their autonomous system number. This is relatively easy; it’ll be in the whois record for any of their IP addresses.

These examples use GNU jwhois, which normally appears on Linux systems. You may have to massage the commands slightly for other whois clients.

Step 1: Do a ‘ping’ on your target domain

$ ping

PING ( 56(84) bytes of data.
64 bytes from ( icmp_seq=1 ttl=46 time=417 ms
64 bytes from ( icmp_seq=2 ttl=48 time=230 ms
64 bytes from ( icmp_seq=3 ttl=48 time=216 ms


Step 2: Now we know the IP we check the ASN (Autonomous System Number) if it really belong to

$ whois -h | grep origin:

origin: AS36646
remarks: * To view the original object, please query the RIPE Database at:


Make sure it actually belongs to Yahoo by doing below command

$ whois -h AS36646 | more

aut-num: AS36646
as-name: Yahoo-YSM-OC2
descr: Yahoo YSM OC2 datacenter
admin-c: AB474-ARIN
tech-c: AB474-ARIN
import: from AS3356 accept ANY
import: from AS3561 accept ANY
import: from AS10310 accept ANY
export: to AS3356 announce AS36646
export: to AS3561 announce AS36646
export: to AS10310 announce AS36646
notify: [email protected]
changed: [email protected] 20202020
source: RADB


Step 3: Now we know that is ASN; let’s get their IPv4 address ranges.

$ whois -h – – -i origin -T route AS36646 | grep route:



And finally their IPv6 address ranges if you want to know also

$ whois -h — -i origin -T route6 AS36646 | grep route6:

route6: 2001:4998:44::/46
route6: 2001:4998:efeb::/48


Repeat for all their ASNs, if they actually have more than one.

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