Date: Tue, 21 Aug 2012 15:51:58 -0600 From: Jamie Gritton <jamie@FreeBSD.org> To: curtis@occnc.com Cc: freebsd-jail@FreeBSD.org Subject: Re: IPv6 multicast sent to jail Message-ID: <503402FE.9080103@FreeBSD.org> In-Reply-To: <201208191735.q7JHZDti072004@gateway2.orleans.occnc.com> References: <201208191735.q7JHZDti072004@gateway2.orleans.occnc.com>
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On 08/19/12 11:35, Curtis Villamizar wrote: > I'm trying to run isc-dhcpd using dhcpd -6 in a jail. No luck. > > The following code is run in the jail and doesn't fail. > > if (inet_pton(AF_INET6, All_DHCP_Relay_Agents_and_Servers, > &mreq.ipv6mr_multiaddr)<= 0) { > log_fatal("inet_pton: unable to convert '%s'", > All_DHCP_Relay_Agents_and_Servers); > } > mreq.ipv6mr_interface = if_nametoindex(info->name); > if (setsockopt(sock, IPPROTO_IPV6, IPV6_JOIN_GROUP, > &mreq, sizeof(mreq))< 0) { > log_fatal("setsockopt: IPV6_JOIN_GROUP: %m"); > } > > where All_DHCP_Relay_Agents_and_Servers is defined as "FF02::1:2". > > Later dhcpd binds to *.517 which can be seen in netstat -an. > > Packets to ff02::1:2.517 are seen on the jailer (as opposed to the > jailee) using tcpdump, but no packets are received by the jailee. > > When the same command from the jailer using a chroot to the jailee > directory, the multicast packets are received. > > Is there a solution to this other than changing the jail from an > implied "ip6=new" with a specific address to "ip6=inherit". What I'd > really like is a yet to be invented "ip6=new+multicast". > > Using "ip6=inherit" would be OK, adding very little exposure (mostly > DoS attack exposure). It would be nice if "ip6=inherit" were > supported in the rc.d/jail framework. > > Before I go changing anything I'm asking whether allowing the > multicast join and then not passing multicast to the jail is > considered a bug and how it should behave (the join should have failed > or the packets should have arrived). If the best workaround for now > is "ip6=inherit" would adding jail_<jailname>_ip[46] variables to the > rc files be viewed as a good solution (with a comment in > /etc/defaults/rc.conf indicating that the interaction between setting > addressing using _ip and _ip_multi and setting _ip4 or _ip6 (setting > an address for each family forces "ip[46]=net" for that AF. > > Curtis Offhand, it does sound like a bug. I imagine the solution would be to reject the join - at least the easy solution to be done first until something more complicated can be done to make jails play nice with multicast. - Jamie
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