term% cat index.txt 6IN4(8) System Manager's Manual 6IN4(8)
NAME
6in4 - 6to4 tunnel of IPv6 through IPv4
SYNOPSIS
ip/6in4 [ -ag ] [ -x netmtpt ] [ local6[/mask] [ remote4 [ remote6 ] ]
]
DESCRIPTION
6in4 sets up and operates a tunnel of IPv6 traffic through an IPv4 con‐
nection.
Local6 and mask define the IPv6 address and subnet of the near end of
the tunnel (mask defaults to for a single-host tunnel). If local6 is
missing or it defaults to
2002:aabb:ccdd::1/48
where aa, bb, cc and dd are the hexadecimal equivalents of the bytes
a.b.c.d in this host's primary IPv4 address.
Remote4 is the IPv4 address of the far end of the tunnel (must be given
explicitly for a configured tunnel, or defaults to the anycast address
192.88.99.1 for 6to4).
Remote6 is the IPv6 address of the far end of the tunnel (used as the
point-to-point destination for routing, and defaults to a link-local
address constructed from remote4).
6in4 forks a pair of background processes to copy packets to and from
the tunnel.
Options are:
-a permit any remote IPv4 address as the far end of a tunnel. This
is likely to be useful for the server side of a tunnel.
-g add a default route to the tunnel for global IPv6 addresses.
-x use the network mounted at netmtpt instead of
EXAMPLES
If your primary IPv4 address is public, you can start a 6to4 tunnel
simply with
ip/6in4 -g
Similarly, you can start a server for 6to4 tunnels with
ip/6in4 -ag
If you use a tunnel broker at address configured to give you a subnet
with address you can start the tunnel with
ip/6in4 -g 2001:1122:3344:5566::/64 5.6.7.8
FILES
/net/ipmux
access to IPv6-in-IPv4 packets
/net/ipifc
packet interface to IPv6 network
SEE ALSO
bridge(3), ipmux in ip(3), linklocal in ipconfig(8)
/lib/rfc/rfc3056
/lib/rfc/rfc3068
BUGS
Needs a kernel with an ipmux driver.
The tunnel client filters addresses fairly conservatively in both di‐
rections. However it's not watertight, and may be flakey in other ways
so don't put too much trust in it.
6IN4(8)