| 2119 | Key words for use in RFCs to Indicate Requirement LevelsS. Bradner | Best Current Practice | March 1997 |
| 2401 | Security Architecture for the Internet ProtocolS. Kent, R. Atkinson · obsoleted by RFC 4301 | Proposed Standard | November 1998 |
| 2406 | IP Encapsulating Security Payload (ESP)S. Kent, R. Atkinson · obsoleted by RFC 4303, RFC 4305 | Proposed Standard | November 1998 |
| 2407 | The Internet IP Security Domain of Interpretation for ISAKMPD. Piper · obsoleted by RFC 4306 | Historic | November 1998 |
| 2409 | The Internet Key Exchange (IKE)D. Harkins, D. Carrel · obsoleted by RFC 4306 | Historic | November 1998 |
| 2560 | X.509 Internet Public Key Infrastructure Online Certificate Status Protocol - OCSPM. Myers, R. Ankney, A. Malpani, S. Galperin, C. Adams · obsoleted by RFC 6960 | Proposed Standard | June 1999 |
| 2960 | Stream Control Transmission ProtocolR. Stewart, Q. Xie, K. Morneault, C. Sharp, H. Schwarzbauer, T. Taylor, I. Rytina, M. Kalla, L. Zhang, V. Paxson · obsoleted by RFC 4960 | Proposed Standard | October 2000 |
| 3057 | ISDN Q.921-User Adaptation LayerK. Morneault, S. Rengasami, M. Kalla, G. Sidebottom · obsoleted by RFC 4233 | Proposed Standard | February 2001 |
| 3280 | Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) ProfileR. Housley, W. Polk, W. Ford, D. Solo · obsoleted by RFC 5280 | Proposed Standard | May 2002 |
| 3309 | Stream Control Transmission Protocol (SCTP) Checksum ChangeJ. Stone, R. Stewart, D. Otis · obsoleted by RFC 4960 | Proposed Standard | September 2002 |
| 3331 | Signaling System 7 (SS7) Message Transfer Part 2 (MTP2) - User Adaptation LayerK. Morneault, R. Dantu, G. Sidebottom, B. Bidulock, J. Heitz | Proposed Standard | September 2002 |
| 3332 | Signaling System 7 (SS7) Message Transfer Part 3 (MTP3) - User Adaptation Layer (M3UA)G. Sidebottom, Ed., K. Morneault, Ed., J. Pastor-Balbas, Ed. · obsoleted by RFC 4666 | Proposed Standard | September 2002 |
| 3436 | Transport Layer Security over Stream Control Transmission ProtocolA. Jungmaier, E. Rescorla, M. Tuexen | Proposed Standard | December 2002 |
| 3554 | On the Use of Stream Control Transmission Protocol (SCTP) with IPsecS. Bellovin, J. Ioannidis, A. Keromytis, R. Stewart | Proposed Standard | July 2003 |