Password file migration (v0.4.0)

Format

username:sha256:<salt_hex>:<hash_hex>

Legacy plain-text lines (username:password) still work when reject_plaintext_passwords=false (default for backward compatibility).

In rsyncd.conf:

[auth]
enabled = true
method = password
password_file = /etc/simple-rsyncd/passwd
reject_plaintext_passwords = true

Plain-text entries in the password file are skipped at load time when this flag is true.

Generate a hash with the daemon linked against OpenSSL (or any tool producing the same format):

# Example: hash password "secret" for user "backup"
# Use simple-rsyncd test helper or C++ PasswordHasher in a one-off tool.

Recommended approach for operators:

Copy passwd to passwd.bak
For each user, replace user:plain with user:sha256:... using a small script that calls OpenSSL SHA-256 with random salt matching PasswordHasher format in auth.cpp
Set reject_plaintext_passwords=true
Run simple-rsyncd test --config /etc/simple-rsyncd/rsyncd.conf
Verify login before removing passwd.bak

Storage uses SHA-256 + salt, not bcrypt/argon2. Suitable for beta/staging; plan upgrade for high-threat environments (v0.5.0+).
Passwords in environment variables or process listings remain an operator concern.