--- /dev/null
+# official debian repository:
+ deb http://ftp.debian.org/debian/ buster main contrib non-free
+ deb-src http://ftp.debian.org/debian/ buster main contrib non-free
+
+# security updates:
+ deb http://security.debian.org/ buster/updates main contrib
+ deb-src http://security.debian.org/ buster/updates main contrib