Should I be using ipv6_activate_all_interfaces or ip6addrctl_policy="ipv6_prefer"

[John Hay]

On Wed, Aug 27, 2014 at 11:59:25AM +0000, Bjoern A. Zeeb wrote:
> 
> On 27 Aug 2014, at 06:31 , Jonathan Price <freebsd at jonathanprice.org> wrote:
> 
> > On 2014-08-27 01:40, Peter Wemm wrote:
> >> On Tuesday 26 August 2014 10:40:27 freebsd at jonathanprice.org wrote:
> >>> Hello,
> >>> 
> >>> I am configuring a server with IPv4 and IPv6 addresses and have noticed that
> >>> FreeBSD seems to be preferring IPv4, such as when establishing SSH
> >>> connections.
> >>> 
> >>> After reading through /etc/defaults/rc.conf, and later /etc/rc.d/ip6addrctl
> >>> I have come to the conclusion that I have two ways to tell FreeBSD to
> >>> prefer IPv6:
> >>> 
> >>> 1) Add ipv6_activate_all_interfaces to /etc/rc.conf
> >>> 2) Add ip6addrctl_policy="ipv6_prefer" to /etc/rc.conf
> >>> 
...
> > However, it does sound like for my purposes it would make more sense to use ip6addrctl_policy=?ipv6_prefer" as that is more explicitly the feature I want, rather than getting it inadvertently through the other knob.
> 
> Yes. Definitively.  I am not sure if it has happened but if IPv6 config is configured through rc.conf that setting should be(come) default.
> 

It does not seem so yet (anymore, it was like that many moons ago). A new
install of 11-current, with the following in rc.conf:

#################
hostname="fbsd-11-test"
ifconfig_em0="DHCP"
ifconfig_em0_ipv6="inet6 accept_rtadv"
sshd_enable="YES"
#################

Output of ip6addrctl:

#################
jhay at fbsd-11-test:~ % ip6addrctl 
Prefix                          Prec Label      Use
::1/128                           50     0        0
::/0                              40     1       13
::ffff:0.0.0.0/96                100     4        0
2002::/16                         30     2        0
2001::/32                          5     5        0
fc00::/7                           3    13        0
::/96                              1     3        0
fec0::/10                          1    11        0
3ffe::/16                          1    12        0
jhay at fbsd-11-test:~ %
#################

telnet to a machine with both ipv6 and ipv4 addresses:

#################
jhay at fbsd-11-test:~ % telnet dolphin
Trying 146.64.28.14...
telnet: connect to address 146.64.28.14: Connection refused
Trying 2001:4200:7000:3:223:aeff:fea5:ef...
telnet: connect to address 2001:4200:7000:3:223:aeff:fea5:ef: Connection refused
telnet: Unable to connect to remote host
jhay at fbsd-11-test:~ % 
#################

I think if an IPv6 address is configured on a machine, it should prefer ipv6
addresses. That would match what the rest are doing.

Regards

John
-- 
John Hay -- jhay at meraka.csir.co.za / jhay at meraka.org.za