[Bug 1853669] Re: systemd resolves own hostname to link local ipv6 address
Dan Streetman
ddstreet at canonical.com
Fri Dec 6 14:17:57 UTC 2019
> I don't understand what lsof tries to tell me here, but naively I'd
assume that systemd-resolved also queries the routing table, and for
that I also attach the output of "route -n -6" at the end of this
message.
that's not correct.
What's the contents of your /etc/hosts file? Contents of
/etc/resolv.conf?
What do these show:
$ systemd-resolve --status
$ systemd-resolve fpc
$ systemd-resolve -t A fpc
$ systemd-resolve -t AAAA fpc
$ dig @10.2.2.3 -t A fpc
$ dig @10.2.2.3 -t AAAA fpc
$ dig @127.0.0.53 -t A fpc
$ dig @127.0.0.53 -t AAAA fpc
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https://bugs.launchpad.net/bugs/1853669
Title:
systemd resolves own hostname to link local ipv6 address
Status in systemd package in Ubuntu:
Incomplete
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.
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