CODEWITHSUNDEEP
pythonmacossshterminalparamiko
PhoenixRising
PhoenixRising

Reputation: 95

Get host key of an ssh server in base 64

I'm using paramiko and I need the host key of an ssh server in base 64 for the following line:

key = paramiko.RSAKey(data=base64.decodestring('...'))

Does anyone know of a way either through the Mac OS X terminal, in a python script, or something else to find this? Thanks

Upvotes: 1

Views: 5457

Answers (3)

James Andariese
James Andariese

Reputation: 567

>>> from paramiko.client import SSHClient

>>> client = SSHClient()
>>> client.connect('hostname')
# This probably will fail since there's no auth set here
>>> rsa_key = client.get_transport().get_remote_server_key()
<paramiko.rsakey.RSAKey object at 0x109305e90>
# however, this still exists
>>> rsa_key.get_base64()
u'AAAAB3NzaC1y...Nhd'

Since you're using paramiko already, you probably will want to just stop at rsa_key and not make a new one with get_base64() since rsa_key is of RSAKey type already.

A server can define a non-RSA key as well (or multiple) but if you know that it only returns RSA, this will obviously always return RSA. It will depend on which key is negotiated.

Upvotes: 1

Robᵩ
Robᵩ

Reputation: 168726

You can retrieve the server's public key from the server itself, without having to authenticate yourself to the server.

import paramiko
import socket
import sys

for arg in sys.argv[1:]:
        sock = socket.socket()
        sock.connect((arg, 22))
        trans = paramiko.transport.Transport(sock)
        trans.start_client()
        k = trans.get_remote_server_key()
        # On my machine, this returns a paramiko.RSAKey
        print k.get_base64()

Upvotes: 4

mjp
mjp

Reputation: 65

Do you need to do this only once, or do you need to be able to programmatically grab the host key at runtime? If only once, 

ssh -v <hostname>

will show you the host key.

Upvotes: 1

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