From 20093751ec96b43d87f0850fc3ad541237405564 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Fri, 1 Nov 2013 14:50:24 +0100
Subject: [PATCH] Print a reminder to users to set or disable the root password

---
 nixos/modules/config/users-groups.nix | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/nixos/modules/config/users-groups.nix b/nixos/modules/config/users-groups.nix
index 79570fc2571..714de646eb7 100644
--- a/nixos/modules/config/users-groups.nix
+++ b/nixos/modules/config/users-groups.nix
@@ -258,6 +258,22 @@ in
         fi
       '';
 
+    # Print a reminder for users to set a root password.
+    environment.interactiveShellInit =
+      ''
+        if [ "$UID" = 0 ]; then
+            read _l < /etc/shadow
+            if [ "''${_l:0:6}" = root:: ]; then
+                cat >&2 <<EOF
+        Warning: Your root account has a null password, allowing local users
+        to login as root.  Please set a non-null password using \`passwd', or
+        disable password-based root logins using \`passwd -l'.
+        EOF
+            fi
+            unset _l
+        fi
+      '';
+
     system.activationScripts.users = stringAfter [ "groups" ]
       ''
         echo "updating users..."