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Thu, May 11, 2017 9:00 AM

Setting up IPV6

I have business internet with a /29 (it gives me ipv4 5 addresses)

This has been working well for the last 5 years or so I've had the line.


There are 4 devices on the outside of the network, one centos (physical), one ubuntu (virtual) and two FreeBSD (physical).


The Ubuntu device is acting as a ipv4 router.


I pulled my information from the comcast router for my IPV6 network addresses and set up static addresses on each of my devices. The FreeBSD devices are ad00::44 and ad00::45, the ad00 being the end of the network address. These all show up as a /64.


From what I understand I have a /56 available, This would make the 00 in the above address  available for subnets. I set up the FreeBSD devices as ipv6 routers and rtavd (radvd for freebsd) is handing out the IP and routing infromation just fine. I have the subnet ad01 set up on the inside of my network now. All that is working EXEPT those devices getting out past the comcast router.


I've done a traceroute. I can see the data hitting the inside of the FreeBSD box, the outside of the FreeBSD box, but when it reaches the comcast router it's being rejected.


Here is a tcpdump of one of the packets origionating from an inside server passing through the ad00 interface (outside) on the freebsd box, hitting the comcast router and being rejected (I've removed much of the actual address information). in this example, I'm using an inside box to ping an IPV6 address at google. This test work on the freebsd box and other devices directly on the outside network.


15:43:57.243071 IP6 (hlim 63, next-header ICMPv6 (58) payload length: 64) X:X:X:ad01:5054:ff:fec7:8078 > [icmp6 sum ok] ICMP6, echo request, seq 6
15:43:57.243285 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 112) X:X:X:ad00:c604:15ff:fe32:66bb > X:X:X:ad01:5054:ff:fec7:8078: [icmp6 sum ok] ICMP6, destination unreachable, unknown unreach code (5)


I'm not sure where to go. Is there something I'm missing about comcasts network? Is there something I need to ask for? 


Respected Member


575 Messages

4 y ago

Hello HugMe  and welcome to forums.


I apologize for taking so long to respond to your post. From looking over your information the only thing that comes to mind is the IPv6 firewall being enabled on your modem. This is a feature that you have access to disable by logging into the device (default login  information, IP address: User Name: cusadmin Password: highspeed)


HugMe in regards to your specific modem I have sent you a private message to help resolve your problem. Please check you inbox for more.


Thank You