Ipv6 interfering with ipv4 NAT'ing?

  • I can't figure out if this is an IPv6 thing, a NAT problem, or what.
    I just got centurylink fiber installed and configure pfsense using pppoe with them.

    I have two internal interfaces, a LAN, and a DMZ that is firewalled off from the LAN.  Both of course NAT out through the WAN interface.

    on the DMZ I have a linksys spa2102 voip ATA adapter.  This is not ipv6 capable.  If I enable ipv6 on the DMZ interface (the WAN is configured for 6rd and the DMZ is configured to track the WAN interface and request a prefix of 1) the SIP connection is unable to register.

    Packet captures show the register going out, but no response coming back at all.  The firewall logs don't show any packets being blocked.

    If I disable IPv6 on the DMZ, everything works fine.  IPv6 is also enabled on the LAN.

    Has anyone seen aything like this?  I don't quite understand how just simply enabling IPv6 would prevent the ata adapter from registering.

    Additional datapoints, I have 2 more hosts on DMZ, and both hosts have no problems connecting out to the world with ipv4 or ipv6.

  • upon further testing, this is unrelated to ipv6.  It looks like it has to do with stable table tracking.

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