CentOS does not build the "ipddp" module / does not set "CONFIG_IPDDP" in the kernel config, so appears to not be affected by this issue. I would be happy if Ubuntu resolved this issue by likewise no longer shipping this module.
For anyone not familiar, some background: DDP was Apple's proprietary networking protocol, used by Apple and early Macintosh computers prior to the widespread adoption of TCP and Ethernet. "IP-over-DDP" (what this particular module is used for) encapsulates IP packets inside DDP packets. It's useful if your network supports DDP traffic but does not support IP traffic -- for example, Apple's LocalTalk serial-port-based networking standard. So you can browse the Web on a Mac that predates Ethernet. (Apple stopped supporting LocalTalk with the initial release of Mac OS X, and stopped shipping computers with LocalTalk-compatible serial ports at about the same time.) The kernel's "Documentation/networking/ipddp.txt" says the following regarding setting up the "ipddp" module: """ Decapsulation - You will need to download a software package called MacGate. (...) Encapsulation - You will need to download a software daemon called ipddpd. """ (If the module isn't configured with one of these two programs, it doesn't do anything useful.) MacGate was last shipped in Debian Potato; the sources from that release appear to want a 2.0 kernel, and do not compile on my machine. I can't find sources for ipddpd online. The functionality provided by the "ipddp" module is now also mostly provided by the userspace program "macipgw": https://github.com/zero2sixd/macipgw This program builds and works correctly on a stock Ubuntu LTS 14.04 x86_64 machine with a modified Ubuntu 4.2 kernel that omits "CONFIG_IPDDP=m" from its kernel config. (Of course, it doesn't work with stock Ubuntu kernels because of this bug.) ** Description changed: - Ubuntu's kernel is compiled with CONFIG_IPDDP=m, which means that IP- - over-DDP packets (DDP type 22) are silently dropped. This is true even - if the generated "ipddp" module is not loaded; so if this module is - compiled, there is no way to listen for these packets. + Ubuntu's kernel is compiled with CONFIG_IPDDP=m, which, because of an + upstream bug, means that IP-over-DDP packets (DDP type 22) are silently + dropped. This is true even if the generated "ipddp" module is not + loaded; so if this module is compiled, there is no way to listen for + these packets. One solution would be to fix the module. Another (what CentOS appears to do?) would be to not compile the "ipddp" module at all -- remove CONFIG_IPDDP from the kernel's config. Copying from the upstream bug for specific details: https://bugzilla.kernel.org/show_bug.cgi?id=115031 - """ + """ When a kernel is compiled with "ipddp" as a module, but the module is not loaded, DDP packets of type 22 (IP-over-DDP) are silently dropped. Steps to reproduce: 1. Compile a kernel with 'ipddp' as a module. Do not load the module; make sure it is not loaded, just compiled. 2. Open up a DDP listening socket for packets of type 22, on any supported network interface. (Tested with Ethernet.) 3. Attempt to connect to and send data to this socket Expected behavior: - If module is loaded, packets will be unwrapped by the kernel and emitted as IP packets (so will not be received by the listening DDP socket) - If module is not present, packets will be passed through to the listening DDP socket Actual behavior: - If module is not present but was compiled during the kernel build process, packets are silently discarded by the kernel - If module is not present and was not compiled during the kernel build process, packets are passed through as expected """ -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1559772 Title: IP-over-DDP packets dropped To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-lts-wily/+bug/1559772/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
