Why socket option "IPV6_ROUTER_ALERT" is invalid?
 

I want router catch the ip packet which mark router alert label, change it and send to the next hop. Not just forward it immediately.
So I set IP_ROUTER_ALERT and IPV6_ROUTER_ALERT option for ipv4 and ipv6 socket. IP_ROUTER_ALERT was just fine and I can do what I expect. However when I set on IPV6_ROUTER_ALERT, it tells me "Protocol not available" (errno = 92). And This option can be found in "$Kernel/net/ipv6/ipv6_sockglue.c"

Could anyone help? Thanks ~~~

Is your kernel compiled with IPv6 support enabled?
Kevin Barry

I think I've opened all of the IPv6 features...(version 2.6.28)