** Description changed: + [Impact] + LightDM doesn't pick the best IPv6 address on offer from clients (picks link-local addresses over non link-local). + + [Test Case] + 1. Start LightDM with XDMCP server enabled + 2. Connect XDMCP client that sends IPv6 link-local addresses to LightDM + + Expected result: + LightDM picks a non link-local address and is able to connect to the client + + Observed result: + LightDM picks the link-local address address if it is first + + [Regression Potential] + Small risk of behaviour change due to new IP selection method. + + Original report: + I've discovered a problem in lightdm XDMCP using link-local IPv6 addresses without interface index to connect to X server. It has been originally reported at https://bugzilla.redhat.com/show_bug.cgi?id=1322775. The problem can be fixed by having the XDMCP client not transmitting link-local addresses in the request, but if it does, lightdm XDMCP server can be a lot smarter if the attached patch is applied. It changes the X server address selection order to set the lowest preference to link-local addresses, even if matching the source address or family. This is not 100% full-proof: if only link-local addresses have been received, one of them is used anyway. In this case, a complete solution would be to determine and set the address interface index if not ambiguous. - However, this patch fixes the problem for most of the non-pathological + However, this patch fixes the problem for most of the non-pathological cases.
-- You received this bug notification because you are a member of Desktop Packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/1575200 Title: Error connecting to X server via IPv6 Status in Light Display Manager: Fix Released Status in Light Display Manager 1.10 series: Fix Committed Status in Light Display Manager 1.16 series: Fix Committed Status in Light Display Manager 1.18 series: Fix Released Status in lightdm package in Ubuntu: Fix Released Status in lightdm source package in Trusty: Fix Committed Status in lightdm source package in Wily: Fix Committed Status in lightdm source package in Xenial: Fix Committed Bug description: [Impact] LightDM doesn't pick the best IPv6 address on offer from clients (picks link-local addresses over non link-local). [Test Case] 1. Start LightDM with XDMCP server enabled 2. Connect XDMCP client that sends IPv6 link-local addresses to LightDM Expected result: LightDM picks a non link-local address and is able to connect to the client Observed result: LightDM picks the link-local address address if it is first [Regression Potential] Small risk of behaviour change due to new IP selection method. Original report: I've discovered a problem in lightdm XDMCP using link-local IPv6 addresses without interface index to connect to X server. It has been originally reported at https://bugzilla.redhat.com/show_bug.cgi?id=1322775. The problem can be fixed by having the XDMCP client not transmitting link-local addresses in the request, but if it does, lightdm XDMCP server can be a lot smarter if the attached patch is applied. It changes the X server address selection order to set the lowest preference to link-local addresses, even if matching the source address or family. This is not 100% full-proof: if only link-local addresses have been received, one of them is used anyway. In this case, a complete solution would be to determine and set the address interface index if not ambiguous. However, this patch fixes the problem for most of the non-pathological cases. To manage notifications about this bug go to: https://bugs.launchpad.net/lightdm/+bug/1575200/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
