The stf documentation suggests the following configuration. This will result in traffic originating from the 6to4 address for which reply traffic will not be accepted. # ifconfig ne0 inet 133.4.5.6 netmask 0xffffff00 # ifconfig stf0 inet6 2002:8504:0506:0000:a00:5aff:fe38:6f86 \ prefixlen 16 alias deprecated link0 # route add -inet6 2002:: -prefixlen 16 ::1 # route change -inet6 2002:: -prefixlen 16 ::1 -ifp stf0 Fix: Use "anycast" rather than "deprecated" so that the kernel will choose a different IPv6 source address. # ifconfig ne0 inet 133.4.5.6 netmask 0xffffff00 # ifconfig stf0 inet6 2002:8504:0506:: prefixlen 16 alias anycast link0 # route add -inet6 2002:: -prefixlen 16 ::1 # route change -inet6 2002:: -prefixlen 16 ::1 -ifp stf0 I tested this on a FreeBSD 4.11 box but I don't believe this part of the stack has changed much since then. The above documentation is from FreeBSD 8. How-To-Repeat: Configure the system as above and try to talk to any a machine with a 6to4 address. You can observe the traffic with tcpdump. e.g. "tcpdump -i ne0 -n -p not udp and not tcp and not arp" will remove most of the extranious packets.
For bugs matching the following criteria: Status: In Progress Changed: (is less than) 2014-06-01 Reset to default assignee and clear in-progress tags. Mail being skipped