The Internet Engineering Task Force is standardizing security protocols (IPsec protocols) that are compatible with IPv6 and can be retrofitted into IPv4. The protocols are transparent to both applications and users and can be implemented without modifying application programs. The current protocol versions were published as Internet drafts in March 1998. The article overviews the proposed security architecture and the two main protocols-the IP Security Protocol and the Internet Key Management Protocol-describes the risks they address, and touches on some implementation requirements. IPsec's major advantage is that it can provide security services transparently to both applications and users. Also, the application programs using IPsec need not be modified in any way. This is particularly important when securing application programs that are not available in source code, which is common today. This transparency sets IPsec apart from security protocols that operate above the Internet layer. At present, IPsec is likely to be used in conjunction with and complemented by other security technologies, mechanisms, and protocols. Examples include firewalls and strong authentication mechanisms for access control, and higher layer security protocols for end-to-end communication security. In the near future, however, as virtual private networking and corporate intranets and extranets mature, IPsec is likely to be deployed on a larger scale.