interface captures IPv6 TCP traffic,
for implementing userland IPv6-to-IPv4 TCP relay
interface can be created at runtime using the
command or by setting up a
configuration file for
Special action will be taken when IPv6 TCP traffic is seen on a router,
and the routing table suggests routing it to the
In this case, the packet will be accepted by the router,
regardless of the list of IPv6 interface addresses assigned to the router.
The packet is captured by an IPv6 TCP socket, if it has the
flag turned on and it has matching address/port pairs.
allows captured IPv6 TCP traffic to be relayed to some
specific destination addresses.
Userland programs, such as
can use this behavior to relay IPv6 TCP traffic to IPv4 TCP traffic.
The program can accept some specific IPv6 TCP traffic, perform
to get the IPv6 destination address specified by the client,
and perform application-specific address mapping to relay IPv6 TCP to IPv4 TCP.
flag on an IPv6 TCP socket can be set by using
with level set to
and optname set to
To handle error reports by ICMPv6, some of the ICMPv6 packets routed to the
interface will be delivered to IPv6 TCP, as well.
To understand how
can be used, take a look at the source code of
interface implements a potentially dangerous operation,
great care must be taken when configuring the
To avoid possible misuse, the
must be set to
prior to use of the interface.
no packet is captured by the
interface is intended to be used on routers, not on hosts.