Paramiko SSH Failing With "Server '...' Not Found In Known_hosts" When Run On Web Server

I am trying to use Paramiko to make an SSH communication between 2 servers on a private network. The client server is a web server and the host server is going to be a 'worker' ser

Solution 1:

You can hard-code the host key in your Python code, using HostKeys.add:

import paramiko
from base64 import decodebytes

keydata = b"""AAAAB3NzaC1yc2EAAAABIwAAAQEA0hV..."""
key = paramiko.RSAKey(data=decodebytes(keydata))
 
client = paramiko.SSHClient()
client.get_host_keys().add('example.com', 'ssh-rsa', key)
client.connect(...)

• This is based on my answer to:
  Paramiko "Unknown Server".

• To see how to obtain the fingerprint for use in the code, see my answer to:
  Verify host key with pysftp.

• If using pysftp, instead of Paramiko directly, see:
  PySFTP failing with "No hostkey for host X found" when deploying Django/Heroku

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Or, as you are connecting within a private network, you can give up on verifying host key altogether, using AutoAddPolicy:

client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
client.connect(...)

(This can be done only if you do not need the connection to be secure, like when connecting within a private network)