glm-5.1
596c89ce24
Rename all crates, CLI commands, constants, type names, doc comments, and documentation from wraith to alknet. Includes wire-protocol changes: ALPN wraith-ssh -> alknet-ssh, reserved destination prefix wraith- -> alknet-, SSH auth username wraith -> alknet.
30 lines
1.9 KiB
Markdown
30 lines
1.9 KiB
Markdown
# ADR-017: Stealth Mode — Protocol Multiplexing on Port 443
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## Status
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Accepted
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## Context
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When running a alknet server with TLS transport on port 443, the server should be indistinguishable from a regular HTTPS web server to port scanners and deep packet inspection (DPI) systems. This is important for censorship circumvention — if SSH traffic on port 443 is detectable, it can be blocked.
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After the TLS handshake completes, the server sees a raw byte stream. SSH protocol identification starts with `SSH-2.0-`, while HTTP starts with HTTP method verbs (GET, POST, etc.). The server can inspect the first bytes to determine the protocol.
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## Decision
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When `--stealth` is enabled with TLS transport:
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1. After completing the TLS handshake, peek at the first few bytes of the connection
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2. If the connection starts with `SSH-2.0-`, proceed with SSH session via `server::run_stream()`
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3. If the connection starts with anything else (HTTP, random data), respond with `HTTP/1.1 404 Not Found\r\nServer: nginx\r\n\r\n` and close the connection
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This makes the server appear as an nginx web server returning 404 errors to all non-SSH connections. Scanners and DPI systems see a typical HTTPS site with no SSH exposure.
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The fake response uses `Server: nginx` headers to match the most common web server profile.
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## Consequences
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- **Positive**: TLS+alknet servers on port 443 are indistinguishable from ordinary HTTPS sites to automated scanners.
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- **Positive**: Simple implementation — just peek at the first bytes and branch.
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- **Positive**: Consistent with censorship circumvention best practices.
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- **Negative**: Legitimate HTTPS traffic to the same port gets a 404. If the same IP needs to serve real web content, use a reverse proxy (nginx/haproxy) in front that routes by SNI or path.
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- **Negative**: The `--stealth` flag only applies to TLS transport. It has no effect on TCP or iroh transports.
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## References
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- [server.md](../server.md) |