[Dovecot][Netfilter] Report failed logins from mailcowauth.php, anchor default rules

data/conf/dovecot/auth/mailcowauth.php

@@ -68,6 +68,8 @@ require_once 'functions.acl.inc.php';
 
 
 $isSOGoRequest = $post['real_rip'] == getenv('IPV4_NETWORK') . '.248';
+// real_rip is the address that connected to Dovecot (for proxied connections the proxy), client_ip the client
+$client_ip = filter_var($post['client_ip'] ?? '', FILTER_VALIDATE_IP) ? $post['client_ip'] : $post['real_rip'];
 $result = false;
 if ($isSOGoRequest) {
   // This is a SOGo Auth request. First check for SSO password.
@@ -121,7 +123,14 @@ if ($result) {
   http_response_code(200); // OK
   $return['success'] = true;
 } else {
-  error_log("MAILCOWAUTH: Login failed for user " . $post['username'] . " with service " . $post['service'] . " from IP " . $post['real_rip']);
+  // Same line for the log and netfilter, which counts it for IMAP, POP3, Sieve and SMTP (Postfix asks Dovecot);
+  // SOGo logins have their own rule
+  $failed = "MAILCOWAUTH: Login failed for user " . $post['username'] . " with service " .
+    preg_replace('/[^a-z0-9]/', '', strtolower((string)$service)) . " from IP " . $client_ip;
+  error_log($failed);
+  if (!$isSOGoRequest) {
+    $redis->publish("F2B_CHANNEL", $failed);
+  }
   http_response_code(401); // Unauthorized
 }
 

data/conf/dovecot/auth/passwd-verify.lua

@@ -1,8 +1,4 @@
 function auth_password_verify(request, password)
-  if request.domain == nil then
-    return dovecot.auth.PASSDB_RESULT_USER_UNKNOWN, "No such user"
-  end
-
   local json = require "cjson"
   local ltn12 = require "ltn12"
   local https = require "ssl.https"
@@ -11,7 +7,10 @@ function auth_password_verify(request, password)
   local req = {
     username = request.user,
     password = password,
+    -- address that connected to Dovecot, for proxied connections the proxy
     real_rip = request.real_rip,
+    -- address of the client, also for proxied connections
+    client_ip = request.rip,
     service = request.service
   }
   local req_json = json.encode(req)

data/conf/dovecot/dovecot.conf

@@ -51,13 +51,6 @@ recipient_delimiter = +
 auth_master_user_separator = *
 mail_shared_explicit_inbox = yes
 mail_prefetch_count = 30
-passdb {
-  driver = lua
-  args = file=/etc/dovecot/auth/passwd-verify.lua blocking=yes cache_key=%s:%u:%w
-  result_success = return-ok
-  result_failure = continue
-  result_internalfail = continue
-}
 # try a master passwd
 passdb {
   driver = passwd-file
@@ -67,8 +60,9 @@ passdb {
 }
 # check for regular password - if empty (e.g. force-passwd-reset), previous pass=yes passdbs also fail
 # a return of the following passdb is mandatory
+# each check asks mailcowauth.php, which reports a failed login to netfilter once
 # cache_key with password: the lua default (%u) would let a temporary failure fall back to the negative entry
-# of a passdb lookup (master logins) and log "unknown user", which netfilter counts as failed login
+# of a passdb lookup (master logins) and reject the login as unknown user
 passdb {
   driver = lua
   args = file=/etc/dovecot/auth/passwd-verify.lua blocking=yes cache_key=%s:%u:%w