Raymii.org

One of my clients wanted to block a few social networking websites. Since they have no IPv6 (yet) I figured the simplest way was to block access to the entire IP range. This won't work for all the CDN networks they use, but it does get you started.

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To find all the ranges beloning to an AS number you can query the whois.radb.net server with the AS number.

For Facebook for example:

whois -h whois.radb.net '!gAS32934'
A1063
204.15.20.0/22 69.63.176.0/20 66.220.144.0/20 66.220.144.0/21 69.63.184.0/21 69.63.176.0/21 74.119.76.0/22 69.171.255.0/24 173.252.64.0/18 69.171.224.0/19 69.171.224.0/20 103.4.96.0/22 69.63.176.0/24 173.252.64.0/19 173.252.70.0/24 31.13.64.0/18 31.13.24.0/21 66.220.152.0/21 66.220.159.0/24 69.171.239.0/24 69.171.240.0/20 31.13.64.0/19 31.13.64.0/24 31.13.65.0/24 31.13.67.0/24 31.13.68.0/24 31.13.69.0/24 31.13.70.0/24 31.13.71.0/24 31.13.72.0/24 31.13.73.0/24 31.13.74.0/24 31.13.75.0/24 31.13.76.0/24 31.13.77.0/24 31.13.96.0/19 31.13.66.0/24 173.252.96.0/19 69.63.178.0/24 31.13.78.0/24 31.13.79.0/24 31.13.80.0/24 31.13.82.0/24 31.13.83.0/24 31.13.84.0/24 31.13.85.0/24 31.13.86.0/24 31.13.87.0/24 31.13.88.0/24 31.13.89.0/24 31.13.90.0/24 31.13.91.0/24 31.13.92.0/24 31.13.93.0/24 31.13.94.0/24 31.13.95.0/24 69.171.253.0/24 69.63.186.0/24 31.13.81.0/24 179.60.192.0/22 179.60.192.0/24 179.60.193.0/24 179.60.194.0/24 179.60.195.0/24 185.60.216.0/22 45.64.40.0/22 204.15.20.0/22 69.63.176.0/20 69.63.176.0/21 69.63.184.0/21 66.220.144.0/20 69.63.176.0/20

For CloudVPS:

whois -h whois.radb.net '!gAS35470'
A248
194.60.207.0/24 79.170.88.0/21 89.31.96.0/21 217.170.21.0/24 193.138.204.0/22 178.18.80.0/20 31.3.96.0/21 141.138.192.0/20 212.32.226.0/24 37.34.48.0/21 37.230.96.0/21 93.191.128.0/21 185.21.188.0/22 213.187.240.0/21 85.222.224.0/21 185.3.208.0/22

To find an AS number, you can query this whois server with the IP address. Linode for example:

$ whois -h whois.radb.net  178.79.155.1
route:          178.79.128.0/18
descr:          Linode-2
origin:         AS15830
mnt-by:         Linode-mnt
changed:        tasaro@linode.com 20100510
source:         RIPE
remarks:        ****************************
remarks:        * THIS OBJECT IS NOT VALID
remarks:        * Please note that all personal data has been removed from this object.
remarks:        * To view the original object, please query the RIPE Database at:
remarks:        * http://www.ripe.net/whois
remarks:        ****************************

And then their AS number:

$ whois -h whois.radb.net '!gAS15830'
A3937
217.68.16.0/22 217.20.46.0/24 [...] 213.52.183.0/24 213.52.182.0/24 212.111.40.0/24

A block can then be issued with the following iptables command:

iptables -A INPUT -d 217.68.16.0/22 -j DROP

Where -d is the destination you want to make unreachable.

If you have the ipset extension enabled you can create a set of all the ranges:

ipset -N blocked_nets nethash
ipset -A blocked_nets 194.60.207.0/24
ipset -A blocked_nets 79.170.88.0/21
ipset -A blocked_nets 89.31.96.0/21
ipset -A blocked_nets 217.170.21.0/24
ipset -A blocked_nets 193.138.204.0/22
ipset -A blocked_nets 178.18.80.0/20
ipset -A blocked_nets 31.3.96.0/21
ipset -A blocked_nets 141.138.192.0/20
ipset -A blocked_nets 212.32.226.0/24
ipset -A blocked_nets 37.34.48.0/21
ipset -A blocked_nets 37.230.96.0/21
ipset -A blocked_nets 93.191.128.0/21
ipset -A blocked_nets 185.21.188.0/22
ipset -A blocked_nets 213.187.240.0/21
ipset -A blocked_nets 85.222.224.0/21
ipset -A blocked_nets 185.3.208.0/22

And create the rules to filter based on the ipset, which is faster when you have a large amount of IP's and ranges.

iptables -I INPUT -m set --match-set blocked_nets src,dst -j DROP

Tags: as , block , firewall , iptables , radb , ripe , snippets , whois