The current Internet is based on the destination address forwarding in which the source address remains unverified. However, one of the root causes of Internet security problems is the untrustworthy source address. As the Internet plays an increasingly important role in political and economic fields, the security of the Inter-domain Internet becomes more crucial. For instance, the US Department of Homeland Security (DHS) has included the Inter-domain routing security in the national strategy of US information security. In recent years, innovation and evolution of the Internet are significantly undermined by the IP spoofing based distributed denial of service attacks, most of which are Inter-domain and transnational. Therefore, the Inter-domain source address validation becomes extremely important for Internet security. Although there are many techniques proposed in the relevant fields, none of them are appropriate for large-scale deployment. This paper reviews the existing research and standard progress of Inter-domain source address validation technology. First, the reasons and consequences of the lack of source address security are analyzed, and the significance of source address validation is illustrated by examining the progress of the technical standardization. Next, the advantages and disadvantages of various existing important source address validation methods are summarized. Then, the difficulties and challenges faced by the current Inter-domain source address validation technology are discussed. Finally, the prospective research directions and design principles are proposed as a reference for potential future works.