francoismichel / ssh3

> [!NOTE] > SSH3 is probably going to change its name. It is still the SSH Connection Protocol (RFC4254) running on top of HTTP/3 Extended connect, but the required changes are heavy and > too distant from the philosophy of popular SSH implementations to be considered for integration. The specification draft has already been renamed ("Remote Terminals over HTTP/3"), > but we need some time to come up with a nice permanent name. SSH3: faster and rich secure shell using HTTP/3 SSH3 is a complete revisit of the SSH protocol, mapping its semantics on top of the HTTP mechanisms. It comes from our research work and we (researchers) recently proposed it as an Internet-Draft (draft-michel-remote-terminal-http3-00). In a nutshell, SSH3 uses QUIC+TLS1.3 for secure channel establishment and the HTTP Authorization mechanisms for user authentication. Among others, SSH3 allows the following improvements: • Significantly faster session establishment • New HTTP authentication methods such as OAuth 2.0 and OpenID Connect in addition to classical SSH authentication • Robustness to port scanning attacks: your SSH3 server can be made **invisible** to other Internet users • UDP port forwarding in addition to classical TCP port forwarding • All the features allowed by the modern QUIC protocol: including connection migration (soon) and multipath connections > [!TIP] > Quickly want to get started ? Checkout how to install SSH3. You will learn to setup an SSH3 server and use the SSH3 client. ⚡ SSH3 is faster Faster for session establishment, not throughput ! SSH3 offers a significantly faster session establishment than SSHv2. Establishing a new session with SSHv2 can take 5 to 7 network round-trip times, which can easily be noticed by the user. SSH3 only needs 3 round-trip times. The keystroke latency in a running session is unchanged. SSH3 (top) VS SSHv2 (bottom) session establishement with a 100ms ping towards the server. 🔒 SSH3 security While SSHv2 defines its own protocols for user authentication and secure channel establishment, SSH3 relies on the robust and time-tested mechanisms of TLS 1.3, QUIC and HTTP. These protocols are already extensively used to secure security-critical applications on the Internet such as e-commerce and Internet banking. SSH3 already implements the common password-based and public-key (RSA and EdDSA/ed25519) authentication methods. It also supports new authentication methods such as OAuth 2.0 and allows logging in to your servers using your Google/Microsoft/Github accounts. 🧪 SSH3 is still experimental While SSH3 shows promise for faster session establishment, it is still at an early proof-of-concept stage. As with any new complex protocol, **expert cryptographic review over an extended timeframe is required before reasonable security conclusions can be made**. We are developing SSH3 as an open source project to facilitate community feedback and analysis. However, we **cannot yet endorse its appropriateness for production systems** without further peer review. Please collaborate with us if you have relevant expertise! 🥷 Do not deploy the SSH3 server on your production servers for now Given the current prototype state, we advise *testing SSH3 in sandboxed environments or private networks*. Be aware that making experimental servers directly Internet-accessible could introduce risk before thorough security vetting. While hiding servers behind secret paths has potential benefits, it does not negate the need for rigorous vulnerability analysis before entering production. We are excited by SSH3's future possibilities but encourage additional scrutiny first. 🥷 Your SSH3 public server can be hidden Using SSH3, you can avoid the usual stress of scanning and dictionary attacks against your SSH server. Similarly to your secret Google Drive documents, your SSH3 server can be hidden behind a secret link and only answer to authentication attempts that made an HTTP request to this specific link, like the following: ssh3-server -bind 192.0.2.0:443 -url-path By replacing by, let's say, the random value , your SSH3 server will only answer to SSH3 connection attempts made to the URL and it will respond a to other requests. Attackers and crawlers on the Internet can therefore not detect the presence of your SSH3 server. They will only see a simple web server answering 404 status codes to every request. **NOTE WELL**: placing your SSH3 server behind a secret URL may reduce the impact of scanning attacks but will and must *never* replace classical authentication mechanisms. The secret link should only be used to avoid your host to be discovered. Knowing the secret URL should not grant someone access to your server. Use the classical authentication mechanisms described above to protect your server. 💐 SSH3 is already feature-rich SSH3 provides new feature that could not be provided by the SSHv2 protocol. Brand new features • **UDP port forwarding**: you can now access your QUIC, DNS, RTP or any UDP-based server that are only reachable from your SSH3 host. UDP packets are forwarded using QUIC datagrams. • **X.509 certificates**: you can now use your classical HTTPS certificates to authenticate your SSH3 server. This mechanism is more secure than the classical SSHv2 host key mechanism. Certificates can be obtained easily using LetsEncrypt for instance. • **Hiding** your server behind a secret link. • **Keyless** secure user authentication using **OpenID Connect**. You can connect to your SSH3 server using the SSO of your company or your Google/Github account, and you don't need to copy the public keys of your users anymore. Famous OpenSSH features implemented This SSH3 implementation already provides many of the popular features of OpenSSH, so if you are used to OpenSSH, the process of adopting SSH3 will be smooth. Here is a list of some OpenSSH features that SSH3 also implements: • Parses on the server • Certificate-based server authentication • mechanism when X.509 certificates a…