I am running a router on OpenWRT 15.05.1 and I did notice, that it does not send out Gratuitous ARP packets on a change of the IP address, nor on a reboot, nor on change of the Ethernet link state.
In the meanwhile I found out, that there is an option called
/etc/sysctl.conf, but it does not work for some reaseon.
cat /proc/sys/net/ipv4/conf/br-lan/arp_notify returns
1 right now, so I guess it should be enabled, but it still does not send the Gratuitous ARP packet on one of the mentioned situations.
I also stopped the firewall with
/etc/init.d/firewall stop to prevent any issues from there.
arping -A -I br-lan x.x.x.x sends it properly, so in general it is possible to create and send such a packet.
What is required to send out a Gratuitous ARP packet by the Linux kernel at an OpenWRT system on a change of the network settings, on a reboot or a link state change?
(I probably can find a scripted solution for it with the hotplug system, but I want to know why it does not work with
arp_notify how I think it should)