I have conducted more investigation into the cause, resulting in a significant restatement of the issue.
As far as this bug is concerned, it appears there has been no regression, indeed no change in behavior in ifconfig (net-tools package) or ifup (ifupdown package). However it could be argued that all along they have not handled dummy devices very well. The big change appears to be in modprobe (kmod package). As of xenial it behaved the same is insmode (also kmod package) but as of bionic it behaves differently. In particular, insmod tickles the device in such a way that dummy0 comes into existence (in a down state) whereas bionic modprobe leaves it nonexistent. (Higher-numbered devices such as dummy1 are nonexistent in all cases, when the module is newly installed.) The "ip link add" command is fully capable of bringing a dummy device into existence, but apparently neither ifconfig nor ifup has ever had this capability. This is a problem for dummy1 (always) and, what's worse, for dummy0 (as of bionic). You can see the gory details by comparing the typescripts attached to this comment (for xenial) and the next (for bionic). So ... even though the change in behavior occurred in modprobe, it could be argued that the new modprobe behavior is more logical, because it treats dummy0 and dummy1 the same now. By the same token, since dummy1 was never handled well by ifconfig or ifup, it could be argued that the best way to proceed would be to make those programs more robust. Crib the code from "ip link add" to bring the device into existence when appropriate. ** Attachment added: "xenial: insmod and modprobe behave the same" https://bugs.launchpad.net/ubuntu/+source/net-tools/+bug/1828749/+attachment/5264584/+files/dummy-xenial.logg -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1828749 Title: ifconfig dummy0 : Device not found To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/1828749/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
