Bug#805401: /bin/ping6: ping6 does not correctly handle avahi .local addresses

[David Godfrey]

Package: iputils-ping
Version: 3:20121221-4ubuntu1.1
Severity: important
File: /bin/ping6
Tags: ipv6

Dear Maintainer,

* What led up to the situation?
* What exactly did you do (or not do) that was effective (or
ineffective)?
* What was the outcome of this action?
* What outcome did you expect instead?

*** End of the template - remove these template lines ***
Lets say we have a host called foo on the local network that is correctly
configured to work with avahi and ipv6
ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
state UP group default qlen 1000
link/ether ****************
inet 192.168.1.5/24 brd 192.168.1.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::216:3eff:fe80:c25b/64 scope link
valid_lft forever preferred_lft forever

running
ping foo.local
works just fine and shows the IP address pinged as 192.168.1.5

running
ping6 -I eth0 fe80::216:3eff:fe80:c25b
works just fine and shows the IP address pinged as fe80::216:3eff:fe80:c25b

running
avahi-resolve-host-name foo.local
returns
foo.local fe80::216:3eff:fe80:c25b

However
ping6 -I eth0 foo.local
Fails with error
unknown host
It should have pinged fe80::216:3eff:fe80:c25b

It appears that for an avahi .local address ping6 only resolves the ipv4
address, the same as ping does.




-- System Information:
Debian Release: jessie/sid
APT prefers trusty-updates
APT policy: (500, 'trusty-updates'), (500, 'trusty-security'), (500, 'trusty')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.13.0-24-generic (SMP w/8 CPU cores)
Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages iputils-ping depends on:
ii libc6 2.19-0ubuntu6.6
ii libcap2 1:2.24-0ubuntu2
ii libgnutls-openssl27 2.12.23-12ubuntu2.2

Versions of packages iputils-ping recommends:
ii libcap2-bin 1:2.24-0ubuntu2

iputils-ping suggests no packages.

-- no debconf information

[Benjamin Peter]

Package: iputils-ping
Version: 3:20180629-2
Followup-For: Bug #805401

Dear Maintainer,

just a moment after writing I found an article, saying to modify
nsswitch.conf as follows

hosts: files mdns_minimal [NOTFOUND=return] dns mdns
#hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4

Maybe this could be a setting for everyone?

https://debian-administration.org/article/655/Running_IPv6_in_practice


thanks

Ben

-- System Information:
Debian Release: buster/sid
APT prefers unstable
APT policy: (500, 'unstable')

Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.18.0-2-amd64 (SMP w/6 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8),
LANGUAGE=en_US:en (charmap=UTF-8)

Shell: /bin/sh linked to /bin/dash

Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages iputils-ping depends on:

ii libc6 2.27-6
ii libcap2 1:2.25-1.2
ii libidn2-0 2.0.5-1
ii libnettle6 3.4-1

Versions of packages iputils-ping recommends:

ii libcap2-bin 1:2.25-1.2

[Benjamin Peter]

Package: iputils-ping
Version: 3:20180629-2
Followup-For: Bug #805401

Dear Maintainer,

cool that I found someone already described the problem.

It still exists in 2018.

-- System Information:

Debian Release: buster/sid
APT prefers unstable

APT policy: (500, 'unstable')

Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.18.0-2-amd64 (SMP w/6 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8),

LANGUAGE=en_US:en (charmap=UTF-8)

Shell: /bin/sh linked to /bin/dash

Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages iputils-ping depends on:

ii libc6 2.27-6
ii libcap2 1:2.25-1.2
ii libidn2-0 2.0.5-1
ii libnettle6 3.4-1

Versions of packages iputils-ping recommends:

ii libcap2-bin 1:2.25-1.2

[Noah Meyerhans]

Control: reassign -1 libnss-mdns

On Sat, Oct 06, 2018 at 04:53:00PM +0200, Benjamin Peter wrote:
> just a moment after writing I found an article, saying to modify
> nsswitch.conf as follows
>
> hosts: files mdns_minimal [NOTFOUND=return] dns mdns
> #hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4
>
> Maybe this could be a setting for everyone?
>
> https://debian-administration.org/article/655/Running_IPv6_in_practice

This isn't an issue specific to ping/ping6. If the reference to mdns in
nsswitch.conf needs to be modified in some way, or the documentation
needs to be changed, this should be handled within the mdns related
packages.

noah

[Simon McVittie]

Control: retitle -1 ping6 does not resolve Avahi .local addresses by default
Control: severity -1 wishlist
Control: forwarded -1 https://github.com/lathiat/nss-mdns/issues/62
Control: merge 466014 -1
Control: affects 466014 iputils-ping

On Sat, 06 Oct 2018 at 16:53:00 +0200, Benjamin Peter wrote:
> just a moment after writing I found an article, saying to modify
> nsswitch.conf as follows
>
> hosts: files mdns_minimal [NOTFOUND=return] dns mdns
> #hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4
>
> Maybe this could be a setting for everyone?

The reason why this is not the default is that it significantly slows
down name resolution in some programs. More details are available in
upstream bug <https://github.com/lathiat/nss-mdns/issues/62>.

The next upload of nss-mdns will mention this in README.Debian. I don't
intend to change the default in Debian unless the upstream developer of
nss-mdns changes their recommendation, but you are welcome to make this
configuration change locally.

smcv