In response to feedback from operational security communities, CAIDA's source address validation measurement project (https://spoofer.caida.org) is automatically generating monthly reports of ASes originating prefixes in BGP for systems from which we received packets with a spoofed source address. We are publishing these reports to network and security operations lists in order to ensure this information reaches operational contacts in these ASes. This report summarises tests conducted within usa, can. Inferred improvements during May 2024: none inferred Source Address Validation issues inferred during May 2024: ASN Name First-Spoofed Last-Spoofed 209 CENTURYLINK-US-LEGACY-QWEST 2016-08-16 2024-05-25 40676 AS40676 2016-08-29 2024-05-26 27364 ACS-INTERNET 2016-09-27 2024-05-27 20412 CLARITY-TELECOM 2016-09-30 2024-05-31 46573 GLOBAL-FRAG-NETWORKS 2019-05-16 2024-05-31 21804 ACCESS-SK 2019-06-09 2024-05-31 46997 2021-12-22 2024-05-25 12183 TALKIE-COMMUNICATIONS 2022-12-10 2024-05-31 23352 SERVERCENTRAL 2023-04-04 2024-05-23 3701 NERONET 2023-04-18 2024-05-31 400282 2023-04-27 2024-05-31 21623 SPACELINK 2023-05-07 2024-05-04 202400 2023-05-08 2024-05-26 394684 WISPERNET 2024-01-17 2024-05-30 55 UPENN 2024-01-30 2024-05-14 394195 CLEARNETWORX 2024-03-22 2024-05-29 33544 WILINE 2024-03-28 2024-05-02 20326 TERASWITCH 2024-04-15 2024-05-06 203168 2024-04-25 2024-05-02 399486 2024-05-07 2024-05-07 214961 2024-05-14 2024-05-30 393530 TLU 2024-05-22 2024-05-29 19935 CRRS 2024-05-29 2024-05-29 Further information for these tests where we received spoofed packets is available at: https://spoofer.caida.org/recent_tests.php?country_include=usa,can&no_block=1 Please send any feedback or suggestions to spoofer-info@caida.org