rpm -qf /etc/apparmor.d/usr.sbin.dnsmasq
apparmor-profiles-2.10-3.2.noarch

Name: libvirt
Version: 1.2.18.2-5.1

since i installed the new version of libvirt on Leap, apparmor was blocking.
virsh net-start: 
error: Failed to start network fixed
error: internal error: Failed to apply firewall rules /usr/sbin/iptables -w
--table filter --insert INPUT --in-interface fixedbr0 --protocol tcp
--destination-port 67 --jump ACCEPT: iptables v1.4.21: can't initialize
iptables table `filter': Permission denied

the way that i fixed this : 

etc/apparmor.d/usr.sbin.dnsmasq 

# libvirt lease helper
  /usr/lib{,64}/libvirt/libvirt_leaseshelper ix,
  /{,var/}run/leaseshelper.pid rwk,
+  /bin/bash/ ix,