The first admin gets a random password, not admin / ipodderx (#321)

A database with no accounts created admin with the hard-coded password
ipodderx, published in the README, the docs and the sample compose
file, and the log line announcing it printed the password. /api/login
is open to anyone who reaches the port, and nothing made anyone change
it, so a fresh install was an admin account anyone could sign into.

Now the password is IPX_ADMIN_PASSWORD when set, for scripted installs,
or 24 random hex characters written to admin-password beside
config.toml, created 0600 so it is never readable by others even for a
moment. The log says where it is, never what it is, as it does for the
web token (#40). Existing databases are untouched: seeding runs only
with no accounts at all.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/ipx/CHANGELOG.md

@@ -28,6 +28,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - A `.torrent` file larger than 10 MB, or slower than the torrent stall limit, is refused. iPX read one into memory however large it was (#330).
 - Feeds, episodes, artwork and `.torrent` files are no longer fetched from internal addresses (loopback, the LAN, Docker's networks), redirects included, unless config.toml's `fetch_internal` lists them. Adding a feed could read what a service inside the network answered (#320).
 - HTTPS connections no longer trust certificates from emSign's distrusted intermediates, and certificate checks use constant-time comparisons: rustls-webpki, webpki-roots and ctutils are updated (#351).
+- A new install's `admin` gets a random password, written to `admin-password` beside config.toml and readable by iPX's user alone, or the one in `IPX_ADMIN_PASSWORD`. Every install began as admin / ipodderx, a password published in the README, and the log printed it (#321).
 
 ## [1.4.0] - 2026-10-19
 

crates/ipx/src/main.rs

@@ -118,9 +118,35 @@ enum UserCmd {
     Rename { name: String, new_name: String },
 }
 
-/// What a brand new database starts with, so there is always a way in. Announced loudly
-/// in the log, and the first thing the settings page nags about.
-const DEFAULT_PASSWORD: &str = "ipodderx";
+/// The first admin's password: `IPX_ADMIN_PASSWORD` when set, or a random one written to
+/// `admin-password` beside config.toml, readable by the daemon's user alone. Every install began
+/// as admin / ipodderx, published in the README, and nothing made anyone change it (#321).
+/// Returns the password and where it can be found, for the log, which never shows it.
+fn first_password(config_dir: &std::path::Path, from_env: Option<String>) -> Result<(String, String)> {
+    if let Some(p) = from_env.filter(|p| !p.is_empty()) {
+        return Ok((p, "with the password in IPX_ADMIN_PASSWORD".into()));
+    }
+    let password = crate::auth::new_session_token()[..24].to_owned();
+    let file = config_dir.join("admin-password");
+    write_private(&file, &password)?;
+    Ok((password, format!("with the password in {}", file.display())))
+}
+
+/// Writes a secret only its owner may read: created 0600, never readable for a moment between.
+fn write_private(file: &std::path::Path, text: &str) -> Result<()> {
+    use std::io::Write;
+    use std::os::unix::fs::OpenOptionsExt;
+    std::fs::create_dir_all(file.parent().unwrap_or(std::path::Path::new(".")))?;
+    let _ = std::fs::remove_file(file);
+    let mut f = std::fs::OpenOptions::new()
+        .write(true)
+        .create_new(true)
+        .mode(0o600)
+        .open(file)
+        .with_context(|| format!("writing {}", file.display()))?;
+    f.write_all(text.as_bytes())?;
+    Ok(())
+}
 
 /// Everything a command needs. One per process.
 pub struct Ctx {
@@ -611,10 +637,12 @@ async fn daemon(
 
     // A database with nobody in it cannot be signed into.
     if ctx.db.users().await?.is_empty() {
-        ctx.db.create_user("admin", Some(&crate::auth::hash_password(DEFAULT_PASSWORD)?), true).await?;
+        let dir = ctx.config_path.parent().unwrap_or(std::path::Path::new("."));
+        let (password, told) = first_password(dir, std::env::var("IPX_ADMIN_PASSWORD").ok())?;
+        ctx.db.create_user("admin", Some(&crate::auth::hash_password(&password)?), true).await?;
         tracing::warn!(
-            "no accounts yet: created 'admin' with the default password '{DEFAULT_PASSWORD}'. \
-             Change it with `echo -n <password> | ipx user passwd admin`"
+            "no accounts yet: created 'admin' {told}. Sign in and change it, or with \
+             `echo -n <password> | ipx user passwd admin`"
         );
     }
 
@@ -2448,6 +2476,30 @@ fn duration(secs: u64) -> String {
 mod tests {
     use super::*;
 
+    #[test]
+    fn the_first_admin_gets_a_password_nobody_else_knows() {
+        use std::os::unix::fs::PermissionsExt;
+        let dir = std::env::temp_dir().join(format!("ipx-first-password-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+
+        let (a, told) = first_password(&dir, None).unwrap();
+        let file = dir.join("admin-password");
+        assert_eq!(std::fs::read_to_string(&file).unwrap(), a);
+        assert_eq!(std::fs::metadata(&file).unwrap().permissions().mode() & 0o777, 0o600);
+        assert!(told.contains("admin-password") && !told.contains(&a), "the log says where, not what: {told}");
+        assert_eq!(a.len(), 24);
+        assert_ne!(a, "ipodderx");
+        assert_ne!(first_password(&dir, None).unwrap().0, a, "each new database gets its own");
+
+        std::fs::remove_dir_all(&dir).unwrap();
+        let (b, told) = first_password(&dir, Some("chosen".into())).unwrap();
+        assert_eq!(b, "chosen");
+        assert!(!told.contains("chosen"));
+        assert!(!file.exists(), "a password set in the environment is not written anywhere");
+        assert_eq!(first_password(&dir, Some(String::new())).unwrap().0.len(), 24, "empty means unset");
+        std::fs::remove_dir_all(&dir).unwrap();
+    }
+
     #[test]
     fn a_feed_is_due_after_its_wait_and_daily_with_nobody_subscribed() {
         let cfg = config::Config::default();