On 06/09/14 08:07 AM, Felix Fietkau wrote: > On 2014-09-06 08:25, Daniel Dickinson wrote: >> If I posted from the right account, it would help for asking asking a >> question... >> >> At the risk of seeming a complete n00b despite being far from it, why am >> I seeing this in iftop on BB-rc3 using iftop on the WAN? >> >> all-systems.mcast.net => 7.249.33.1 >> all-systems.mcast.net <= 7.249.33.1 >> >> Which whois says is an arin.net IP (which is early arpanet DoD network >> IIRC). >> >> It cannot be blocked via iptables which has me curious as to exactly >> what kernel subsystem is doing this and why. > It's probably IGMP traffic, used to join/leave multicast groups. No need > to worry about this at all. > > - Felix >
Since AFAIK I don't have anything doing IPv4 multicast on the wan of the router (unless openwrt does some such) then I presume you mean that it's random hosts broadcasting subscribe/unsubcribe to multicast groups to anyone who will listen (and send multicast for the group to the subscribed hosts) but is really irrelevant because nothing is doing multicast on the wan (unless there is actual multicast usage that I don't know about,e.g. if ipv6 stack means ipv4 multicast does get used even though there is no ipv6 given out upstream); I do know that the multicast forwarding is not an issue (since it's turned off in the kernel unless you run a multicast routing daemon AIUI (or is it now possible to do some type of minimal config via iproute?)), I'm just was surprised to see the traffic, and haven't been able find much (especially current) documentation of multicast on linux (and don't hack on linux kernel networking code though I have been a consumer of netlink when necessary). Regards, Daniel _______________________________________________ openwrt-devel mailing list [email protected] https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
