SSH to literal IPv6 address

[Dick Visser]

Hi

I'm trying to set up a quick test host and have added this entry in my
~/.ssh/config:

# Test host
Host imapsync
Hostname 2001:610:148:f00d:20c:29ff:fe14:ccfe


Just issuing "ssh imapsync" works fine.

I have this corresponding in my ansible inventory:

# test host
imapsync

But when I try to run "ansible imapsync -m setup", I get:

"SSH Error: data could not be sent to the remote host. Make sure this
host can be reached over ssh".


It turns out that the literal IPv6 address is the culprit.
If I enable IPv4 on the host and change the ssh config to:

# Test host
Host imapsync
Hostname 192.87.38.66

Then things work.

Is there another way of specifying a literal IPv6 address.


PS I also tested using DNS by adding the name to /etc/hosts, and that
seems to work as well.
But the whole point of having ssh config's "Hostname" and ansible's
inventory is to no use DNS.

Thanks!





--
Dick Visser
Sr. System & Network Engineer
GÉANT

Want to join us? We're hiring: https://www.geant.org/jobs

[Johannes Kastl]

On 07.02.17 10:38 Dick Visser wrote:

> # Test host
> Host imapsync
> Hostname 2001:610:148:f00d:20c:29ff:fe14:ccfe

> Is there another way of specifying a literal IPv6 address.

I thought ssh needed IPv6 addresses in square brackets (to avoid
confusion with ports added as suffix)?

Host imapsync
Hostname [2001:610:148:f00d:20c:29ff:fe14:ccfe]

Johannes

[Dick Visser]

Nope that doesn't work, neither in .ss/config nor on the command line.
You need the Port option, or -p on the command line.

The bracket notation isn't used by OpenSSH.

I know that for web browsers the brackets are mandatory when using
IPv6 literals.

[Johannes Kastl]

On 07.02.17 12:23 Dick Visser wrote:

> Nope that doesn't work, neither in .ss/config nor on the command
> line. You need the Port option, or -p on the command line.

As a workaround, what happens if you append the port?

Host imapsync
Hostname [2001:610:148:f00d:20c:29ff:fe14:ccfe]:22

This should be valid ssh syntax, at least I have some of those in my
config or known_hosts.

Johannes

[Dick Visser]

It doesn't work here:

~$ ssh imapsync
ssh: Could not resolve hostname
[2001:610:148:f00d:20c:29ff:fe14:ccfe]:22: nodename nor servname
provided, or not known

This is on MacOS using OpenSSH_7.3p1, LibreSSL 2.4.1.
But I just tried on an Ubuntu box (OpenSSH_7.2p2 Ubuntu-4ubuntu2.1,
OpenSSL 1.0.2g 1 Mar 2016) and the same result there.

Not a show stopper but I'd like to avoid using scarce IPv4 addresses.

Dick

[Johannes Kastl]

On 07.02.17 13:13 Dick Visser wrote:

>> This should be valid ssh syntax, at least I have some of those in
>> my config or known_hosts.

> It doesn't work here:

Sorry, my mistake, those were not in Hostname declarations.

I do not have a ipv6 host handy, so I can't test...

Johannes

[Kai Stian Olstad]

On 07. feb. 2017 10:38, Dick Visser wrote:
> I'm trying to set up a quick test host and have added this entry in my
> ~/.ssh/config:
>
> # Test host
> Host imapsync
> Hostname 2001:610:148:f00d:20c:29ff:fe14:ccfe
>
>
> Just issuing "ssh imapsync" works fine.
>
> I have this corresponding in my ansible inventory:
>
> # test host
> imapsync
>
> But when I try to run "ansible imapsync -m setup", I get:
>
> "SSH Error: data could not be sent to the remote host. Make sure this
> host can be reached over ssh".

Just for fun I tested this, it work for me.
I'm running Ansible 2.1.2 at the moment.

--
Kai Stian Olstad

[Dick Visser]

Just check the output of -vvvvv and ran the same command in a shell:

dick.visser@MacBookAir-DIck:~$ ssh -C -o ControlMaster=auto -o
ControlPersist=60s -o KbdInteractiveAuthentication=no -o
PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey
-o PasswordAuthentication=no -o ConnectTimeout=20 -o
ControlPath=/Users/dick.visser/.ansible/cp/ansible-ssh-%h-%p-%r
imapsync
unix_listener: "/Users/dick.visser/.ansible/cp/ansible-ssh-2001:610:148:f00d:20c:29ff:fe14:ccfe-22-visser.yQ7UwntkXwvGTUmk"
too long for Unix domain socket

After using the hint from
http://docs.ansible.com/ansible/intro_configuration.html#control-path
things started working.

Dick



On 7 February 2017 at 19:27, Kai Stian Olstad

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