add simple checker

dns-rest-api1.sunet.se/overlay/usr/sbin/knot_lastlogin

@@ -0,0 +1,20 @@
+#!/usr/bin/env python3
+
+import sqlite3
+
+try:
+    with sqlite3.connect('/var/lib/knot_rest/database.db') as conn:
+        cur = conn.cursor()
+        cur.execute('select username, description, logged_in from user')
+        rows = cur.fetchall()
+        for row in rows:
+            username = row[0]
+            description = row[1]
+            if description == None:
+                description = "(no description)"
+            lastlogin = row[2]
+            if lastlogin == None:
+                lastlogin = "***never logged in***"
+            print(f"{username:<27}{description:<27}{lastlogin:<23}")
+except sqlite3.OperationalError as e:
+    print(e)