Enforce 'secure_mode 1' in default syslog.conf file

This disables the "unauthenticated remote disk-filling service" by
default.  A user can easily change this to 0 (or 2) to allow other
systems to log to their syslogd.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

syslog.conf

@@ -66,6 +66,14 @@ mail.err			 /var/log/mail.err
 #
 #*.alert				root,joey
 
+#
+# Secure mode, same as -s, none(0), on(1), full(2).  When enabled
+# only logging to remote syslog server possible, with full secure
+# mode, not even that is possible.  We default to prevent syslogd
+# from opening UDP/514 and receving messages from other systems.
+#
+secure_mode 1
+
 #
 # Include all config files in /etc/syslog.d/
 #