interface captures IPv6 TCP traffic,
for implementing userland IPv6-to-IPv4 TCP relay
interface is created at runtime using interface cloning.
most easily done with the
command or using the
Special action will be taken when IPv6 TCP traffic is seen on a router,
and the default routing table suggests to route 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 will be captured by an IPv6 TCP socket, if it has the
flag turned on and matching address/port pairs.
As a result,
will let you capture IPv6 TCP traffic 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 a IPv6 TCP socket can be set by using
To handle error reports by ICMPv6, some ICMPv6 packets routed to an
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 potentially dangerous operations,
great care must be taken when configuring it.
To avoid possible misuse, the
must be set to
prior to using the interface.
no packets will be captured by the
interface is intended to be used on routers, not on hosts.