-deb http://httpredir.debian.org/debian stretch main contrib non-free
-deb http://security.debian.org/debian-security stretch/updates main contrib non-free
+deb http://deb.debian.org/debian stretch main contrib non-free
+deb http://deb.debian.org/debian-security stretch/updates main contrib non-free
# repository that may contain newer fai packages for stretch
deb [trusted=yes] http://fai-project.org/download stretch koeln