IPv6: 6rd with OpenBSD

Reader David Hill wrote in with an article explaining how to set up 6rd tunneling in OpenBSD:

There are many websites claiming OpenBSD doesn't support 6rd. There are also user-space 6rd implementations that do not work on OpenBSD.
Well, 6rd works just fine with OpenBSD if you do it manually.

My ISP is Charter Communcations. As they slowly roll IPv6 out, they have offered IPv6 connectivity via their 6rd Border Relay.

Their settings are as follows:

6rd Prefix = 2602:100::/32
Border Relay Address = 68.114.165.1
6rd prefix length = 32
IPv4 mask length = 0

So I wrote a quick perl script (excuse the code) to generate a hostname.gif0:

#!/usr/bin/perl

sub convert
{
        my $ip = @_[0];
        my ($a, $b, $c, $d) = (split(/\./, $ip));
        $out = sprintf("%x%x%x%x:%x%x%x%x",
                $a / 16, $a % 16,
                $b / 16, $b % 16,
                $c / 16, $c % 16,
                $d / 16, $d % 16);
        return $out;
}

my ($prefix, $bip, $ip);
print "Enter IPv6 6rd Prefix (2602:100:): ";
chomp($prefix = <STDIN>);
print "Enter IPv4 Border Relay address: ";
chomp($bip = <STDIN>);
print "Enter your public IP: ";
chomp($ip = <STDIN>);

$dest = convert($bip);
$src = convert($ip);

print   "\n\nmtu 1480\n",
        "tunnel ", $ip, " ", $bip, "\n",
        "inet6 alias ", $prefix, $src, "::1 128\n",
        "dest ", $prefix, $dest, "::1\n",
        "!/sbin/route -qn add -inet6 default ", $prefix, $dest, "::1\n";

If I run it with my settings:

$ perl 6rd.pl
Enter IPv6 6rd Prefix (2602:100:): 2602:100:
Enter IPv4 Border Relay address: 68.114.165.1
Enter your public IP: 24.247.20.162


mtu 1480
tunnel 24.247.20.162 68.114.165.1
inet6 alias 2602:100:18f7:14a2::1 128
dest 2602:100:4472:a501::1
!/sbin/route -qn add -inet6 default 2602:100:4472:a501::1

Now I just paste that into /etc/hostname.gif0 and run:

# sh /etc/netstart gif0

Using mtr -6 www.google.com, I see that it is working.

  1.|-- ???                                        100.0     1    0.0   0.0   0.0   0.0   0.0
  2.|-- 2001:506:100:6c::1                          0.0%     1   22.2  22.2  22.2  22.2   0.0
  3.|-- bbr01olvemo-tge0-3-0-4.mo.olve.charter.com  0.0%     1   28.4  28.4  28.4  28.4   0.0
  4.|-- bbr02chcgil-tge0-0-0-4.il.chcg.charter.com  0.0%     1   39.1  39.1  39.1  39.1   0.0
  5.|-- prr01chcgil-tge2-1.il.chcg.charter.com      0.0%     1   37.4  37.4  37.4  37.4   0.0
  6.|-- 2001:4860:1:1:0:4e93:0:18                   0.0%     1   35.5  35.5  35.5  35.5   0.0
  7.|-- 2001:4860::1:0:3f7                          0.0%     1   35.2  35.2  35.2  35.2   0.0
  8.|-- 2001:4860:0:1::4da                          0.0%     1   35.6  35.6  35.6  35.6   0.0
  9.|-- ord08s08-in-x13.1e100.net                   0.0%     1   35.0  35.0  35.0  35.0   0.0

So, that is basically it in a nutshell. If you want to use ipv6 by default, add 'family inet6 inet4' to your /etc/resolv.conf