Adds SFTP as a third remote ISO-library protocol alongside SMB and NFS.
Pure-Rust russh + russh-sftp on the ring crypto backend — no kernel
mount, no subprocess, no OpenSSL, no new C deps. Like NFS (and unlike
SMB), SFTP-sourced ISOs support HTTP Range requests because SFTP opens
a seekable file handle.
- iso-store: SftpShareManager (connect/auth/READDIR/seekable stream),
IsoSource::Sftp, password OR SSH-key auth, trust-on-first-use host-key
pinning, 0600 credential sidecar with a restart-safe derived path.
- http-api: /api/sftp-shares routes, Range-aware ISO dispatch arm,
status/metrics counts, /api/docs entry, `sftp` terminal commands.
- webui: "SFTP (SSH)" protocol option with a password/key auth toggle,
host-key fingerprint display, dashboard tile, updated copy.
SCP was deliberately rejected: sequential-only (no Range) and its crates
wrap libssh2 (C + OpenSSL), which would break the static-musl build.
russh is pinned to =0.55.0: russh 0.61 needs the stable RustCrypto
generation (pkcs8 0.11), which is API-incompatible with the release-
candidate crates bergshamra-crypto pins (pkcs8 =0.11.0-rc.11). 0.55 is
the newest russh on the prior generation (pkcs8 0.7) that coexists. Do
not bump past 0.55 until bergshamra adopts stable RustCrypto.
252 tests pass, clippy clean, static musl x86_64 binary (ring already
present via rustls + bergshamra, so no new crypto/C deps).
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
