I have used netcat to expirement with IPv6.  I initially tried version 1.10 that came with my Linux distro, but had to upgrade to version 2.  I configured the interfaces on my 2 test machines as:
 

  ifconfig eth0 inet6 add fec0:0:0:1::10/64

   ifconfig eth0 inet6 add fec0:0:0:1::11/64

 Then I gave them hostnames in /etc/hosts:
 

  fec0:0:0:1::10 myhost10

  fec0:0:0:1::11 myhost11
 

Then I could send data thru IPv6:
 

  netcat -l -p 5000

  netcat -6 myhost11 5000
 

Later . . .   Jim