Q: paramiko/SSH/ how to get a remote host_key

[Guilherme Polo]

2008/1/21, DHR <dima.hristov at gmail.com>:
> I am connecting from a WindowsXP SP2 machine. When using Putty as an
> SSH client, if you connect for the first time then you get somethign
> like this:
>
> ''' The server's host key is not cached in the registry. You
> have no guarantee that the server is the computer you
> think it is.
> The server's rsa2 key fingerprint is:
> ssh-rsa 1024 7b:e5:6f:a7:f4:f9:81:62:5c:e3:1f:bf:8b:57:6c:5a
> If you trust this host, hit Yes to add the key to
> PuTTY's cache and carry on connecting.
> If you want to carry on connecting just once, without
> adding the key to the cache, hit No.
> If you do not trust this host, hit Cancel to abandon the
> connection. '''
>
> If I get it correctly, Putty is using such a command to recieve the
> host_key the first time it connects to a remote SSH server. Then it
> stores it into the registry. The question is how can I do it from
> Python?

When you call method connect of SSHClient it checks if server's
hostname is in system_hot_keys or any local host keys, if it is not,
the missing host key policy is used. The default policy is to reject
the key and raise an SSHException, but you can change that default
policy to AutoAddPolicy

>
>
> Guilherme Polo wrote:
> > 2008/1/21, DHR <dima.hristov at gmail.com>:
> > > I'm trying to run the simpliest example form paramiko readme(Homepage:
> > > http://www.lag.net/paramiko/), and
> > > cannot find out how to get the remote SSH server host_key.
> > >
> > >
> > > This is the code. It is supposed to connect to a remote SSH host and
> > > execute an 'ls' command:
> > >
> > > import paramiko, base64
> > >
> > > key = paramiko.RSAKey(data=base64.decodestring('AAA...'))
> > > client = paramiko.SSHClient()
> > > client.get_host_keys().add('ssh.example.com', 'ssh-rsa', key)
> > > client.connect('227.112.168.273', username='uname', password='pass')
> > > stdin, stdout, stderr = client.exec_command('ls')
> > > for line in stdout:
> > >     print '... ' + line.strip('\n')
> > >
> > > client.close()
> > >
> > > Now, if I understand it correctly I need to get somehow the host_key
> > > from the server and
> > > write it insted of the 'AAA...' thing. Is there a command to get the
> > > host_key from a remote SSH
> > > server?
> > > --
> > > http://mail.python.org/mailman/listinfo/python-list
> > >
> >
> > You need a key to connect to that server, so you should want this:
> >
> > keys = paramiko.util.load_host_keys(os.path.expanduser('~/.ssh/known_hosts'))
> >
> > Then keys[hostname] should contain a RSAKey object that you are looking for
> >
> >
> > --
> > -- Guilherme H. Polo Goncalves
> --
> http://mail.python.org/mailman/listinfo/python-list
>


-- 
-- Guilherme H. Polo Goncalves