OSX - SSH agent functionality differing based upon CLI arguments

[bryan hunt]

Yes, called as you describe, SSH works correctly (it Forwards Agent). Quirky!

But, called the way I was doing, everything but Agent Forwarding works. 

Strange. Looking further, I found another odd behaviour. 

ssh -o User=vagrant -o Hostname=127.0.0.1 -p 2222 -o Compression=yes -o StrictHostKeyChecking=no -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o IdentitiesOnly=yes -i /Users/bryanhunt/.vagrant.d/insecure_private_key -o ForwardAgent=yes -o LogLevel=DEBUG "" "/bin/sh  -c 'git clone git at bitbucket.org:bryan_picsolve/poc_docker.git /home/vagrant/poc_dockerddd’ "

Note how I added the empty quoted string in the hostname position. 

SSH Agent Forwarding works if I add that empty quoted string. 

If I remove the empty quoted string, the git checkout is executed, but prompts for authentication.

I would expect SSH to completely succeed, or completely fail to execute the command - rather than have the side channel (SSH agent) fail or succeed based upon how I express the command line arguments. 

This is a stock version of the ssh command on OSX.

The checksum is:

MD5 (/usr/bin/ssh) = 35caacee333ebae93d4087ca349738e4

Perhaps another OSX user could verify this behaviour? 

Regards,

Bryan Hunt


On 9 Jan 2014, at 17:21, Markus Friedl <mfriedl at gmail.com> wrote:

> You pass it as an option. 
> 
> But ssh is called like 
> 
> $ ssh [options] hostname [command]
> 
> 
> 
> 
> 
>> Am 09.01.2014 um 16:21 schrieb bryan hunt <picsolvebryan at gmail.com>:
>> 
>> 
>> I don’t understand, in the second example, "ssh -o HostName=127.0.0.1 “, is the very first argument to the program…
>> 
>> 
>> 
>>> On 9 Jan 2014, at 13:21, Markus Friedl <mfriedl at gmail.com> wrote:
>>> 
>>> The 2nd example misses the required hostname argument.
>>> 
>>> 
>>> 
>>> 
>>>> Am 09.01.2014 um 13:32 schrieb bryan hunt <picsolvebryan at gmail.com>:
>>>> 
>>>> 
>>>> Trying to get SSH agent forwarding working for a popular open source configuration management system called Ansible.
>>>> 
>>>> I’ve had some unexpected behaviour, the only cause of which I can find is how I express the command line arguments.
>>>> 
>>>> http://stackoverflow.com/questions/20952689/vagrant-ssh-agent-forwarding-how-is-it-working?noredirect=1#comment31511341_20952689
>>>> 
>>>> In summarise:
>>>> 
>>>> In the first instance I can create a SSH connection, and and execute a remote git clone (via SSH), the Agent Forwarding works, and I am not prompted for credentials:
>>>> 
>>>> ssh vagrant at 127.0.0.1 -p 2222 \
>>>> -o Compression=yes \
>>>> -o StrictHostKeyChecking=no \
>>>> -o LogLevel=FATAL \
>>>> -o StrictHostKeyChecking=no \
>>>> -o UserKnownHostsFile=/dev/null \
>>>> -o IdentitiesOnly=yes \
>>>> -i /Users/bryanhunt/.vagrant.d/insecure_private_key \
>>>> -o ForwardAgent=yes \
>>>> "/bin/sh  -c 'git clone git at bitbucket.org:bryan_picsolve/poc_docker.git /home/vagrant/poc_dockera' "
>>>> Cloning into '/home/vagrant/poc_dockera'...
>>>> 
>>>> In the second instance I express the arguments differently ( -o HostName=127.0.0.1 -o User=vagrant ), and Agent Forwarding doesn’t seem to work:
>>>> 
>>>> ssh -o HostName=127.0.0.1 -o User=vagrant -p 2222 \
>>>> -o Compression=yes \
>>>> -o StrictHostKeyChecking=no \
>>>> -o LogLevel=FATAL \
>>>> -o StrictHostKeyChecking=no \
>>>> -o UserKnownHostsFile=/dev/null \
>>>> -o IdentitiesOnly=yes \
>>>> -i /Users/bryanhunt/.vagrant.d/insecure_private_key \
>>>> -o ForwardAgent=yes \
>>>> "/bin/sh  -c 'git clone git at bitbucket.org:bryan_picsolve/poc_docker.git /home/vagrant/poc_dockerb' "
>>>> /bin/sh  -c 'git clone git at 127.0.0.1's password:
>>>> 
>>>> The client side SSH is:
>>>> 
>>>> OpenSSH_6.2p2, OSSLShim 0.9.8r 8 Dec 2011
>>>> 
>>>> The server side SSH is:
>>>> 
>>>> OpenSSH_5.9p1 Debian-5ubuntu1.1, OpenSSL 1.0.1 14 Mar 2012
>>>> 
>>>> 
>>>> Have any of the list members got an insight into this behaviour ?
>>>> 
>>>> Thanks in advance, 
>>>> 
>>>> Bryan Hunt
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
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>>