OSX - SSH agent functionality differing based upon CLI arguments

[bryan hunt]

But it isn’t. 

"/bin/sh  -c 'git clone git at bitbucket.org:bryan_picsolve/poc_docker.git /home/vagrant/poc_dockerddd’ “ is not interpreted as the hostname, it is executed as a remote command, but without SSH agent working. 

Anyhow, I’m not here to demand a better command line argument parser, merely to verify the behaviour so I can help to resolve the problems that Ansible are having. 

But thank you for the help.

Bryan


On 9 Jan 2014, at 20:12, Markus Friedl <mfriedl at gmail.com> wrote:

> This is due to ssh's flexible argument parsing. If you skip the hostname, them something else is interpreted as the hostname. 
> 
> 
> 
> 
>> Am 09.01.2014 um 18:43 schrieb bryan hunt <picsolvebryan at gmail.com>:
>> 
>> 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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>>>>>> openssh-unix-dev at mindrot.org
>>>>>> https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
>> 
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