fix: expand SSH algorithm list for compatibility with modern OpenSSH …#32
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…servers The hardcoded algorithm list was missing modern algorithms used by OpenSSH 9.x servers (Debian 12, Ubuntu 24.04): - KEX: add curve25519-sha256 and diffie-hellman-group15/16-sha512; remove diffie-hellman-group14-sha1 from primary preference - ServerHostKey: add rsa-sha2-512 and rsa-sha2-256 (RFC 8332) - Cipher: add @openssh.com GCM variants and chacha20-poly1305 - HMAC: add encrypt-then-mac (@openssh.com ETM) variants Legacy algorithms (diffie-hellman-group14-sha1, ssh-rsa, CBC ciphers) are preserved at lower preference for backward compatibility with older SSH servers.
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Thanks @YoungHong1992 for the contribution! Merged via I reviewed the diff carefully before merging: ✅ Targeted change — only touches the algorithm list in ✅ Backward-compatible — all legacy algorithms ( ✅ Addresses a real problem — OpenSSH 9.x on Debian 12 / Ubuntu 24.04 removed many legacy algorithms from its default offer. Without your additions ( ✅ Properly ordered — modern algorithms first (preferred), legacy last (fallback). This matches OpenSSH's own preference ordering. This will ship in the next release. Thanks again for the well-scoped, well-documented fix! 🙏 |
Modern OpenSSH 9.x compatibility — handshake against Debian 12 / Ubuntu 24.04 stock servers (#32, @YoungHong1992). - KEX: curve25519-sha256, dh-group15/16-sha512 - HostKey: rsa-sha2-512/256 (RFC 8332) - Cipher: GCM @openssh.com variants - HMAC: ETM @openssh.com variants Legacy algorithms preserved at lower preference — fully backward-compatible with older servers (CentOS 7, Debian 10, AIX).
The hardcoded algorithm list was missing modern algorithms used by
OpenSSH 9.x servers (Debian 12, Ubuntu 24.04):
curve25519-sha256anddiffie-hellman-group15/16-sha512rsa-sha2-512andrsa-sha2-256(RFC 8332)@openssh.comGCM variants@openssh.comETM) variantsLegacy algorithms (
diffie-hellman-group14-sha1,ssh-rsa, CBC ciphers)are preserved at lower preference for backward compatibility with older
SSH servers.