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networking:asn_autonomous_system_number

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networking:asn_autonomous_system_number [2021/01/04 15:20] – [Determine which IPs actually fall into an ASN] peternetworking:asn_autonomous_system_number [2021/01/04 16:36] (current) – peter
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 ====== Networking - ASN (Autonomous System Number) ====== ====== Networking - ASN (Autonomous System Number) ======
  
-An **[[https://en.wikipedia.org/wiki/Autonomous_system_(Internet)|ASN (Autonomous System Number)]]** refers to a block of IP addresses.+[[Networking:ASN (Autonomous System Number):About ASN (Autonomous System Number)|About ASN (Autonomous System Number)]]
  
-Most large organizations or ISPs are allocated a number of ASNs.+[[Networking:ASN (Autonomous System Number):Determine which IPs actually fall into an ASN|Determine which IPs actually fall into an ASN]]
  
-ASNs can be useful to block an entire organization. Instead of manually having to add hundreds of IP addresses into a firewall rule, you can simply block the entire ASN, which blocks all IPs within that ASN.+[[Networking:ASN (Autonomous System Number):Find a specific ASN|Find a specific ASN]]
  
----- +[[Networking:ASN (Autonomous System Number):Use an ASN to Create an IP Blocklist|Use an ASN to Create an IP Blocklist]]
- +
-===== How to find a specific ASN ===== +
- +
-There are many search tools online such as https://www.ultratools.com/tools/asnInfo. +
- +
-For example, searching for **Google** returns a number of ASNs. +
- +
-{{:networking:asn_-_search_-_google.png?800|}} +
- +
----- +
- +
-===== Determine which IPs actually fall into an ASN ===== +
- +
-Taking AS41264 from the above search as an example: +
- +
-<code bash> +
-whois -h whois.radb.net -- '-i origin AS41264' | grep ^route | grep -v route6 | cut -d" " -f7 | most +
-</code> +
- +
-returns: +
- +
-<code bash> +
-74.125.63.0/24 +
-74.125.58.0/24 +
-74.125.60.0/24 +
-104.132.0.0/16 +
-104.132.0.0/23 +
-104.132.2.0/23 +
-104.132.4.0/23 +
-104.132.6.0/23 +
-104.132.8.0/23 +
-104.132.10.0/23 +
-... +
-</code> +
- +
-<WRAP info> +
-**NOTE:**  The IP addresses within an ASN may change often, so if you do use this for firewalling then update the list regularly. +
-</WRAP> +
- +
- +
----- +
- +
-===== References ===== +
- +
-https://www.apnic.net/get-ip/faqs/asn/ +
- +
-https://en.wikipedia.org/wiki/Autonomous_system_(Internet) +
- +
-https://www.ultratools.com/tools/asnInfo+
  
networking/asn_autonomous_system_number.1609773618.txt.gz · Last modified: 2021/01/04 15:20 by peter
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