Specifications

The open protocols that move your files - straight from the source.

Every file-transfer protocol that Stylus SFTP Server speaks — SFTP, SSH, FTP, FTPS, WebDAV — is defined by an open specification published by the Internet Engineering Task Force. We host the complete verbatim text of each one right here, alongside editorial commentary on what the spec defines and how Stylus SFTP Server implements it.

No external bounce-out. No paywall. No JavaScript-heavy renderers. Each detail page below has the full RFC or draft inline, mirrored under the IETF Trust Legal Provisions, with a link back to the canonical IETF source for current authoritative status. Search-friendly, screen-reader-friendly, and indexed by protocol family.

SSH and SFTP

Secure Shell and the SSH File Transfer Protocol. SFTP runs as a subsystem of SSH and inherits all of SSH's authentication, encryption, and integrity guarantees.

draft-ietf-secsh-filexfer-02 Internet Draft
SSH File Transfer Protocol (SFTP v3)
The de facto SFTP specification. Defines packet format, file attributes, requests, and responses. Every SFTP client and server in production today implements this draft - which was never finalised as an RFC.
Ylonen, LehtinenOctober 2001
RFC 4251 Standards Track
The Secure Shell (SSH) Protocol Architecture
The top-level SSH architecture: how the transport, authentication, and connection protocols compose. The starting point for understanding the SSH stack.
Ylonen, LonvickJanuary 2006
RFC 4252 Standards Track
The Secure Shell (SSH) Authentication Protocol
Password, public-key, and host-based authentication methods for SSH. Defines the message format and exchange that every SSH login follows.
Ylonen, LonvickJanuary 2006
RFC 4253 Standards Track
The Secure Shell (SSH) Transport Layer Protocol
The wire protocol underneath SSH: binary packet format, key exchange, encryption, integrity, server authentication. This is where the cryptographic guarantees live.
Ylonen, LonvickJanuary 2006
RFC 4254 Standards Track
The Secure Shell (SSH) Connection Protocol
Multiplexed channels over a single SSH transport. SFTP rides on this as a subsystem; so do interactive shell, port forwarding, and X11 forwarding.
Ylonen, LonvickJanuary 2006
RFC 4716 Informational
The Secure Shell (SSH) Public Key File Format
The interoperable public-key file format used across SSH implementations - the alternative to OpenSSH's authorized_keys line format.
Galbraith, ThayerNovember 2006
RFC 5656 Standards Track
Elliptic Curve Algorithm Integration in SSH
ECDSA host keys and ECDH key exchange for SSH. The basis for modern, fast, short-key SSH.
Stebila, GreenDecember 2009
RFC 8332 Standards Track
Use of RSA Keys with SHA-256 and SHA-512 in SSH
rsa-sha2-256 and rsa-sha2-512 signature algorithms for SSH. Why your modern SSH client stopped accepting ssh-rsa from older servers.
BiderMarch 2018
RFC 8709 Standards Track
Ed25519 and Ed448 Public Key Algorithms for SSH
Edwards-curve signatures for SSH host and user keys. Modern best-practice alternative to RSA for new deployments.
Harris, VelvindronFebruary 2020

FTP and FTPS

The File Transfer Protocol family, from the 1985 base specification through the security and feature extensions that keep it interoperable in 2026.

RFC 959 Internet Standard
File Transfer Protocol (FTP)
The base FTP specification: control and data connections, commands, response codes, active and passive modes. Still the active Internet Standard for FTP.
Postel, ReynoldsOctober 1985
RFC 2228 Standards Track
FTP Security Extensions
AUTH, ADAT, PROT, PBSZ, CCC, MIC, CONF, ENC - the security command set that RFC 4217 (FTPS) builds on.
Horowitz, LuntOctober 1997
RFC 2389 Standards Track
Feature Negotiation Mechanism for FTP
FEAT and OPTS - how a client discovers which optional commands and parameters a server supports.
Hethmon, ElzAugust 1998
RFC 2428 Standards Track
FTP Extensions for IPv6 and NATs
EPSV and EPRT - the IPv6-aware replacements for PASV and PORT. Required for FTP to traverse modern NATs reliably.
Allman, Ostermann, MetzSeptember 1998
RFC 3659 Standards Track
Extensions to FTP
MLST, MLSD, MDTM, SIZE, REST - machine-parseable directory listings, modification times, file sizes, and restartable transfers.
HethmonMarch 2007
RFC 4217 Standards Track
Securing FTP with TLS
The FTPS specification: how to layer TLS over RFC 959 FTP using the security extensions from RFC 2228. The basis of every "FTP over SSL/TLS" deployment.
Ford-HutchinsonOctober 2005

WebDAV

HTTP-based distributed authoring and versioning. WebDAV is the spec behind every "map a network drive" workflow over the web.

RFC 4918 Standards Track
HTTP Extensions for Web Distributed Authoring and Versioning
The base WebDAV specification: properties, collections, locking, namespace manipulation. Obsoletes RFC 2518.
Dusseault, Ed.June 2007
RFC 3744 Standards Track
WebDAV Access Control Protocol
ACL semantics for WebDAV - principals, privileges, and access control entries on top of the base WebDAV namespace.
Clemm et al.May 2004
RFC 4331 Standards Track
Quota and Size Properties for WebDAV
DAV:quota-available-bytes and DAV:quota-used-bytes - the way a WebDAV client discovers a remote quota.
Korver, DusseaultFebruary 2006

About this library. The editorial commentary on each detail page is written by IVI Technologies. The full specification text on each detail page is reproduced verbatim from the IETF source under the IETF Trust Legal Provisions, which expressly permit this kind of complete mirroring. Each page also carries a link back to the canonical source at rfc-editor.org (or the IETF Datatracker for drafts) so you can confirm the current authoritative status. For any normative reference, defer to the IETF.