ipv6 redirecting to loopback address

vikasmca05 · 03-25-2008, 08:55 AM

Sir I am trying to capture the IPv6 packet through libpcap utility.
I am sending the packet to the IPv6 host in my subnet , and want that
all the packets should be redirected to loopbackaddress, where it can
be captured.But the packets destined for the destination address are
not taking the loopback address.I have statically configured the
gateway of the destination as ::1.

raskin · 03-25-2008, 02:16 PM

Packet on local subnet are not routed through gateway, they are sent directly. But what are you trying to achieve? If you are root on localhost, run tcpdump or wireshark, catching well-formed outgoing IP packets is usually easy with such applications.

vikasmca05 · 03-25-2008, 11:21 PM

I am developing Fragroute for IPv6, for which i am redirecting the ipv6 packets to loopback address and then where i am manipulating the fields of the packet.And then resending them to there original destination.
But firstly I have to redirect them to the loopback address, can you please suggest something for this.Its urgent!!!

raskin · 03-27-2008, 05:30 PM

Look at what tcpdump does.. Use libpcap. You do not need to change gateway - it doesn't work. You can try to achieve something by weird firewall rules, but actually you need just to use libpcap and simply capture the packets.

vikasmca05 · 03-27-2008, 11:24 PM

Actually i have to send back the packets from eth0 interface to the loopback address.
Because if i capture the packet at eth0 interface then original packets will also be sent which i dont want,
I want that only the packets manipulated by me to be sent.
I am also searching for how to know the MAC address of the IPv6 destination, if anyone can please come out with this too..........

raskin · 03-29-2008, 04:26 PM

Try netmask /128. And don't forget to use raw sockets (not IP ones) when sending processed packets from your program..

stsi · 05-06-2009, 02:23 AM

There is no way in linux to route IPv6 traffic via loopback - see
the following comment in net/ipv6/route.c ip6_route_add() function:

/* We cannot add true routes via loopback here,
they would result in kernel looping; promote them to reject routes
*/

stsi · 05-06-2009, 02:24 AM

I've created IPv6-enabled fragroute that works via /dev/net/tun:
http://code.google.com/p/fragroute-ipv6/