I recently came across Team Cymru’s website in the Swiss CTI git repository. The Swiss National Cyber Security Centre NCSC did mention them in the disclaimer for the ASN lookups.
I checked the website out and it looks quite interesting. Also, they offer a free IP to ASN lookup that also works in bulk.
The service has multiple endpoints to query the IP-to-ASN mapping.
Bulk request with netcat
The bulk query file “list01”.
begin
218.92.0.114
104.237.151.140
58.47.106.149
218.92.0.225
104.239.90.253
47.236.252.14
101.100.194.23
endRequesting a bulk response for IP Addresses.
netcat whois.cymru.com 43 < list01 | sort -n > list02The response in list02 will look like this. In my case it took 129.92 seconds to get this response.
Bulk mode; whois.cymru.com [2025-01-10 18:25:38 +0000]
4134 | 218.92.0.114 | 218.92.0.0/16 | CN | apnic | 2001-06-28 | 2025-01-10 18:23:28 GMT | CHINANET-BACKBONE No.31,Jin-rong Street, CN
4134 | 218.92.0.225 | 218.92.0.0/16 | CN | apnic | 2001-06-28 | 2025-01-10 18:23:28 GMT | CHINANET-BACKBONE No.31,Jin-rong Street, CN
4134 | 58.47.106.149 | 58.44.0.0/14 | CN | apnic | 2005-03-29 | 2025-01-10 18:23:28 GMT | CHINANET-BACKBONE No.31,Jin-rong Street, CN
9009 | 104.239.90.253 | 104.239.90.0/23 | GB | ripencc | 2014-11-25 | 2025-01-10 18:23:28 GMT | M247, RO
38719 | 101.100.194.23 | 101.100.194.0/24 | SG | apnic | 2010-12-22 | 2025-01-10 18:23:28 GMT | DREAMSCAPE-AS-AP Dreamscape Networks Limited, AU
45102 | 47.236.252.14 | 47.236.0.0/16 | US | arin | 2016-04-15 | 2025-01-10 18:23:28 GMT | ALIBABA-CN-NET Alibaba US Technology Co., Ltd., CN
63949 | 104.237.151.140 | 104.237.144.0/21 | US | arin | 2014-11-13 | 2025-01-10 18:23:28 GMT | AKAMAI-LINODE-AP Akamai Connected Cloud, SGHTTP
