Merge pull request #100255 from nh2/sshd-default-log-level-info

sshd service: Default to INFO logLevel (upstream default)

2 files changed, 20 insertions, 6 deletions

diff --git a/nixos/modules/services/networking/ssh/sshd.nix b/nixos/modules/services/networking/ssh/sshd.nix
index 227dfe834b2..91caa2ccb42 100644
--- a/nixos/modules/services/networking/ssh/sshd.nix
+++ b/nixos/modules/services/networking/ssh/sshd.nix
@@ -351,15 +351,12 @@ in
 
       logLevel = mkOption {
         type = types.enum [ "QUIET" "FATAL" "ERROR" "INFO" "VERBOSE" "DEBUG" "DEBUG1" "DEBUG2" "DEBUG3" ];
-        default = "VERBOSE";
+        default = "INFO"; # upstream default
         description = ''
           Gives the verbosity level that is used when logging messages from sshd(8). The possible values are:
-          QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. The default is VERBOSE. DEBUG and DEBUG1
+          QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. The default is INFO. DEBUG and DEBUG1
           are equivalent. DEBUG2 and DEBUG3 each specify higher levels of debugging output. Logging with a DEBUG level
           violates the privacy of users and is not recommended.
-
-          LogLevel VERBOSE logs user's key fingerprint on login.
-          Needed to have a clear audit track of which key was used to log in.
         '';
       };
 
diff --git a/nixos/modules/services/security/fail2ban.nix b/nixos/modules/services/security/fail2ban.nix
index 07702bfb9d0..499d3466750 100644
--- a/nixos/modules/services/security/fail2ban.nix
+++ b/nixos/modules/services/security/fail2ban.nix
@@ -45,7 +45,12 @@ in
       enable = mkOption {
         default = false;
         type = types.bool;
-        description = "Whether to enable the fail2ban service.";
+        description = ''
+          Whether to enable the fail2ban service.
+
+          See the documentation of <option>services.fail2ban.jails</option>
+          for what jails are enabled by default.
+        '';
       };
 
       package = mkOption {
@@ -221,6 +226,15 @@ in
           defined in <filename>/etc/fail2ban/action.d</filename>,
           while filters are defined in
           <filename>/etc/fail2ban/filter.d</filename>.
+
+          NixOS comes with a default <literal>sshd</literal> jail;
+          for it to work well,
+          <option>services.openssh.logLevel</option> should be set to
+          <literal>"VERBOSE"</literal> or higher so that fail2ban
+          can observe failed login attempts.
+          This module sets it to <literal>"VERBOSE"</literal> if
+          not set otherwise, so enabling fail2ban can make SSH logs
+          more verbose.
         '';
       };
 
@@ -313,6 +327,9 @@ in
       banaction_allports = ${cfg.banaction-allports}
     '';
     # Block SSH if there are too many failing connection attempts.
+    # Benefits from verbose sshd logging to observe failed login attempts,
+    # so we set that here unless the user overrode it.
+    services.openssh.logLevel = lib.mkDefault "VERBOSE";
     services.fail2ban.jails.sshd = mkDefault ''
       enabled = true
       port    = ${concatMapStringsSep "," (p: toString p) config.services.openssh.ports}