Script for SSH OverTheWire

Question

In my CTF environment, if I want to access an application in a server, I have to perform SSH. Here's what it looks like:

1. (my terminal) ssh username@ssh_ip
2. enter password

The steps start to annoy me because if I have to access the same application more than once, I have to perform these steps multiple times.

Thus, I want to create a script that does this automatically, like './run_everything', which will autorun everything and immediately brings me to the application CLI instantly.

What kind of python library that can do this? I'm not asking for someone to make it for me, but more like asking for advice like what libraries to use and stuff.

Answer 1

Try python api of iTerm2 or use some packages like paramiko.

Answer 2

you can use expect. Though it is not a python library, it is a great tool to automate your terminal commands and easy to use. I have used it to automate ssh logins and automated some basic commands. It has a feature called autoexpect. With that, it'll generate a simple script which can be executed every time to run the commands in order, with a simple modification.

you can find how to use it on this link.

Answer 3

pexpect is a pretty good python library for this. You can use it to input and read output from a terminal.

For example using it to ssh and execute ls:

import pexpect

ssh = 'your server'

child = pexpect.spawn(f'ssh {ssh}', maxread=1)
child.expect(f"{ssh}'s password: ", timeout=120)
child.sendline('password')
child.sendline('ls')

# just printing the output to verify it, but this is not needed
while True:
    print(child.readline())

For your intents and purposes you just need to do is child.sendline('ssh ...') and child.expect and child.sendline the password a second time to get into your actual server from the jump server. From there you can send the command to run your app.

Answer 4

Below is the sample Python SSH Paramiko Library example.

import paramiko

ip='server ip'
port=22
username='username'
password='password'

cmd='some useful command' 

ssh=paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(ip,port,username,password)

stdin,stdout,stderr=ssh.exec_command(cmd)
outlines=stdout.readlines()
resp=''.join(outlines)
print(resp)

My assumption based on your last comment are of below types :

1. As the script is not throwing any error, It may happen that there is no issue in connecting. But in STDOUT the output is not getting stored.
2. The command you are executing , that is not getting executed correctly.

You can execute such a command which does not require any output. It just executes and you will be able to see it. Then you can be sure that the command is actually working and issue is with response. If the command is not working then check for the connectivity.

You can refer to this page later if no solution found from above mentioned points. This is another method called Invoke_Shell. Implement an interactive shell over ssh in Python using Paramiko?