Date: Wed, 13 Jan 2010 09:22:58 -0700 From: Brett Lee <Brett.Lee@Sun.COM> To: freebsd-net@freebsd.org Subject: Re: How to enable IPv6 on a subset of interfaces Message-ID: <4B4DF362.9000007@Sun.COM> In-Reply-To: <25ff90d61001121642l7ac1de26ma7033ca997d90183@mail.gmail.com> References: <4B4CEB41.3000805@Sun.COM> <25ff90d61001121642l7ac1de26ma7033ca997d90183@mail.gmail.com>
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David Horn wrote: > On Tue, Jan 12, 2010 at 4:36 PM, Brett Lee <Brett.Lee@sun.com> wrote: >> Hello, >> >> Using FreeBSD 8.0-RELEASE, and am trying variations in /etc/rc.conf in an >> attempt to enable IPv6 on ONLY one of the systems two interfaces. >> >> Specifically, em0 should be enabled IPv4 DHCP, and bge0 should be enabled >> IPv6 only. >> >> From the KAME link below, and the files /etc/network.subr and >> /etc/defaults/rc.conf, am reading that "ipv6_network_interface" should work; >> however the following still results in em0 obtaining IPv6 addresses: >> >> http://www.kame.net/~suz/freebsd-ipv6-config-guide.txt >> >> ifconfig_em0="DHCP" >> ipv6_enable="YES" >> ipv6_network_interface="bge0" >> ipv6_network_interfaces="bge0" >> >> In another attempt (see link below), it looks like "ifconfig_em0" may >> support a "NOIPV6" param, but in practice it doesn't seem to work for me: >> >> http://lists.freebsd.org/pipermail/freebsd-rc/2007-May/001106.html >> >> ifconfig_em0="DHCP NOIPV6" >> ipv6_enable="YES" >> #ipv6_network_interface="bge0" >> #ipv6_network_interfaces="bge0" >> >> Am hopeful that someone might point out how I could enable this >> configuration. >> >> Thanks in advance! -Brett > > NOIPV6 is not a valid rc.conf configuration token at this time. > > I am assuming that you are using SLAAC for IPv6 prefix/address > distribution (via rtadvd/radvd), and not DHCPv6. > > ipv6_network_interfaces is the correct rc.conf(5) variable to use to > specifically control which interface gets configured using SLAAC via > rtsol(8), but will not stop other interfaces from getting the RA > (Router Advertisement) packet which starts IPv6 SLAAC (Stateless > Autoconfiguration). > > In -current/9.0 there are nice new ifconfig parameters (inet6 > ifdisabled -nud -accept_rtadv) and rc.conf variables that do just what > you are looking for, but they are not in 8.0 at this time. > > In 8.0 you can use the ndp(8) utility to set the -accept_rtadv (and/or > ifdisabled/nud,etc.) flags on a per-interface basis. The > "-accept_rtadv" flag will disable SLAAC for the specified interface, > but must be called before the interface gets the "RA" packet to be > effective. > > You can do an ugly *unsupported hack* in 8.0 to call ndp from within > rc.conf/rc.d startup scripts until the new code makes it into a > release: > > ipv6_enable="YES" > ipv6_network_interfaces="bge0" > ifconfig_em0="DHCP `ndp -i em0 ifdisabled -nud -accept_rtadv >/dev/null 2>&1`" > ifconfig_bge0="UP" > > This will cause some boot-time error messages about not finding ndp > (before /usr is mounted), but these can be ignored, as the backticked > ndp line will be run EVERY time that rc.conf is sourced. This is > just a work-around for 8.0 that happened to work for me at the time. > If someone else has a better solution that fits properly within the > confines of rc.conf, please speak up. > > While on the subject, I have been thinking about putting together a > patchset to experiment with adding some improved logic surrounding > using DHCPv6 vs DHPCPv4 vs SLAAC/RTSOL in the rc.conf scripts and > adding M+0 flag support +rdnss (RFC 5006) support to the kernel and > userland and devd. If I can ever get a working prototype, I will > share to get some feedback. > > Good Luck. > > ---Dave Horn In trying this: ifconfig_em0="DHCP `ndp -i em0 (if?)disabled -nud -accept_rtadv >/dev/null 2>&1`" it seems like it will be "good enough" for our purposes. The em0 interface is not collecting the global SLAAC prefix and forming a global address; it is not learning about routers on that subnet; it is also not collecting reachability information about neighbors. The last one is probably the most important to us. The goal was to eliminate all global AND link local addressing/routing on em0, however, it was mentioned in one of the replies that this is not possible. This question arose from an effort is to use FreeBSD 8.0 to verify a test platform that consists of the myriad of Tahi IPv6 test suites, while still maintaining direct connectivity between this host and the v4/v6 LANs. With the solution above, I expect that this will suffice for our purposes. If not, will fall back to the serial console. Thanks everyone for your replies/suggestions! -Brett
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