Hello to all my dear friends!
whois is an all famous tool to find who the IP belongs to. It tells the person or organization the IP belongs to. But I was looking to find the AS or the Autonomous system of an IP.
What is Autonomous System?
As we know Internet is made up of large networks connected together. And any communication or packet flow happens by traveling from one hop in a network to another hop in another network and so on until it reaches the destination network and the destination hop.
So these large networks or group of networks are called Autonomous System. In short it is named AS. AS has a unified routing policy. A range of IP addresses are allocated to an AS. Cloudflare has describe AS in good details.
I was looking to find AS of an IP because I wanted to confirm that which organization owns that particular IP. And for this there are websites to lookup AS but I was looking for a command line option. And then I found that whois can also tell the AS of an IP.
Find AS of IP using Whois
whois -h whois.cymru.com -v 139.84.171.98
Warning: RIPE flags used with a traditional server.
AS | IP | BGP Prefix | CC | Registry | Allocated | AS Name
20473 | 139.84.171.98 | 139.84.160.0/19 | US | arin | 2020-12-22 | AS-VULTR, US
cymru is a cyber threat intelligence organization. It provides this information for free and I found it really useful. We can see in the above output, that the IP belongs to Vultr’s Autonomous System. In simple terms, the IP belongs to Vultr’s network range.