Protocol not available

[ne-vlezay80]

Runneng with archlinux:

pim6sd: 18:53:33.417 warning - setsockopt(IPV6_ROUTER_ALERT): Protocol not available

Kernel: 5.4.24-rt15-2-rt

[troglobit]

Well, have you checked your kernel config, do you have everything related to IPv6 enabled?

[tycho]

I just ran into this too. It looks like the kernel doesn't like the socket protocol?

    /* RA packet may be delivered ONLY to IPPROTO_RAW socket */
    if (sk->sk_type != SOCK_RAW || inet_sk(sk)->inet_num != IPPROTO_RAW)
        return -ENOPROTOOPT;

mld6_socket is created with IPPROTO_ICMPV6:

     if ((mld6_socket = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6)) < 0)

[troglobit]

Yup, seems you're right. Linux doesn't support the IPV6_ROUTER_ALERT socket option, as far as I can see -> https://code.woboq.org/linux/linux/net/ipv6/raw.c.html#do_rawv6_setsockopt

I haven't checked, but I'm guessing this works on *BSD, likely originating from the KAME project. So this code, like much else in this restoration project, needs porting to Linux. Any and all help is appreciated! :-)

[troglobit]

Warning removed in 6a07b6b. Reasoning inline in code:

On Linux the IPV6_ROUTER_ALERT option can only be modified if the socket() was created
with SOCK_RAW and IPPROTO_RAW, i.e., on Linux this setsockopt() call will fail.