Paramiko SSH 连接错误：socket.gaierror: [Errno 8] nodename 或 servname 提供，或未知

Question

I have some problems with Python and Paramiko. I want to connect to a SSH Server to automatically read some information from different systems.

I tried some Tips I found here but nothing works. I checked the hosts file, reinstall Python using brew, update/upgrade Python and Paramiko, used the ssh-server on my localhost to test. Also running pip to update paramiko and python.

I am very confused. Please let me ask you.

This is my working environment:

• MacOS Sierra 10.12.6
• Python 2.7
• Eclipse
• SSH Library: Paramiko (paramiko-2.2.1-py2.py3-none-any.whl)

The Script: Basic Paramiko SSH Connection

'''
Created on 16.09.2017


'''
import sys
import telnetlib
import paramiko


host = '213.000.000.123'    # 
user = "user"
password = "password"

ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(host, user, password)

Running the Script on Eclipse results with this output:

Traceback (most recent call last):
      File "/Users/tschaefer/Documents/workspace/PythonCMTSLibs/basicSSHSessionModule.py", line 17, in <module>
        ssh.connect(host, user, password)
      File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/paramiko/client.py", line 301, in connect
        to_try = list(self._families_and_addresses(hostname, port))
      File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/paramiko/client.py", line 199, in _families_and_addresses
        hostname, port, socket.AF_UNSPEC, socket.SOCK_STREAM)
    socket.gaierror: [Errno 8] nodename nor servname provided, or not known

Ok, I find out gai=getaddrinfo, also getaddrbyname and so on. So I think there is a problem resolving the host-string to an IP Address. But it doesn't make sense resolving an IP Address to an IP Address. I used explicit IP. Using the "ssh 213.000.000.123" command directly on CLI works fine.

I also tried to connect to "localhost" or "127.0.0.1" or "google.com" or other. The hosts-file-entry is not commented so it's active. Result: the same situation.

NSLOOKUP works correct, so the DNS Lookup works and a DNS server is available.

It seems Python could find the paramiko Library starting in Eclipse, but there is a problem in the Library.

Can anyone help me the see what my eye doesn't see.

Thank a lot!

Greetings

Answer 1

The error message is very misleading. It actually has nothing to do with DNS error.

Apparently the default port that paramiko uses is something other than 22. Once I specified a port, the problem goes away.

port = 22
k = paramiko.RSAKey.from_private_key_file(key_filename)
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
hostname = os.environ['DOCKER_EE_MANAGER_NODE']
username = os.environ['UCP_USER']

ssh.connect(hostname, port, username, pkey = k)

Works! Enjoy!

Answer 2

In the Paramiko documentation you can see that the second positional argument to connect is port

connect(hostname, port=22, username=None, password=None, pkey=None, key_filename=None, timeout=None, allow_agent=True, look_for_keys=True, compress=False, sock=None, gss_auth=False, gss_kex=False, gss_deleg_creds=True, gss_host=None, banner_timeout=None, auth_timeout=None, gss_trust_dns=True, passphrase=None, disabled_algorithms=None)

You are passing user as the second argument, but connect tries to interpret it as port causing the connection to fail. Here is how you can fix the call to connect using keyword arguments.

ssh.connect(host, username=user, password=password)