Public bug reported: Currently, the Linux kernel doesn't provide IPV6_RECVPKTINFO ancillary data on datagrams coming in from IPv4-mapped clients (e.g., ::ffff:192.0.2.1) on INET6 sockets in the default dual personality mode, nor does it honour IPV6_PKTINFO when sending datagrams on such a socket to an IPv4-mapped destination.
This means that an UDP application that requires a server to respond with the same address as it was contacted on cannot reliably work for IPv4 clients, because 1) the server has no way of knowing which address it was contacted on, and even if it did, 2) the kernel would ignore requests to use a specific source address. For a real-life manifestation of this problem, see this OpenVPN bug report: https://community.openvpn.net/openvpn/ticket/306 This has recently been fixed in the net-next upstream tree with the following commits (the first one of which made the 3.14 merge window, the second one will be in 3.15): https://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=4b261c75a99f29c93a0b6babfc180cdf566bd654 https://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=c8e6ad0829a723a74cd2fea9996a3392d2579a18 Enabling IPv6 is getting increasingly important in these days, but at the same time maintaining backwards compatibility with IPv4-only clients is also essential. I'm therefore requesting a backport of the above two commits to the Ubuntu LTS kernel images so that it becomes possible to use OpenVPN (and any other software packages) in dual-stack mode. Tore ** Affects: linux (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1284535 Title: Make IPV6_[RECV]PKTINFO work for IPv4-mapped addresses To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1284535/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
