Most of the times, the first hit (namely the ipv4 address) is all that is used from the DNS query.
In my case, it is essentially a testcase for Tcl's socket, which tries to establish a connection to an unlistened port, and expects a "connection refused" error. But Tcl in this case(namely that the connection gets refused) attempts the connect on the next address- result, which is then the bad ipv6-address. That one then caused an "EINVAL" from the connect() syscall, which it reported up, so the testcase expecting "connection refused" failed. I'm aware that the impact is not very big, but that just explains, why it wasn't already noticed long before. Conclusion is, that DNS should either not return an inet6 link-local address at all, as this cannot be used that way (namely without the name of the network-device), or it should only provide it together with the network-device, if that is possible in the DNS protocol. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/1853669 Title: systemd resolves own hostname to link local ipv6 address Status in systemd package in Ubuntu: New Bug description: I've got an ethernet-device that only has a configured ipv4 address, and some auto-generated link-local (aka "scope link") ipv6 address. Any tool doing a DNS query (and /lib/systemd/systemd-resolved is the DNS-server listening on 127.0.0.53) for this host's hostname gets back two addresses: the correct ipv4 address, and a broken ipv6 address. Unlike on ipv4, it is possible for the same ipv6-address to be assigned to multiple devices, and therefore the address is only valid in the context of the eth-device. Now, if "ifconfig" shows "inet6 fe80::4687:fcff:fe9e:4ac7 prefixlen 64 scopeid 0x20<link>" then "fe80::4687:fcff:fe9e:4ac7" is NOT a connectable address, and syscall connect() typically fails with EINVAL. To make it a valid address, it needs to be suffixed with a "%" and the device name, like: fe80::4687:fcff:fe9e:4ac7%enp4s0 Either the resolver can return the link name attached to the address separated with a "%" char, or it needs to ignore link-local inet6 addresses. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1853669/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
