python ssh in to a jumpserver and then ssh in to a host from the jumpserver to execute a command

Question

I want SSH to a jumpserver. From the jumpserver, I want SSH to a host and execute a command: 'rpm -qa | grep package' and get the output. Once done, I want successfully logout of the host first and then logout of the jump server.

Below is what I have tried thus far:

Import pexpect

options = '-q -oStrictHostKeyChecking=no -oUserKnownHostsFile=/dev/null -oPubkeyAuthentication=no'

child = pexpect.spawn('ssh ssheth@jumpserver %s'%(options), timeout=None)
child.expect(['password: '])
child.sendline('hello123')
child.expect('#')
child.sendline('ssh ssheth@host "rpm -qa | grep -v watch | grep extractor"')
child.expect(['password: '])
child.sendline(password)
child.logfile = fout
child.expect(".*\$ ", timeout=None)
child.close()

This throws the below exception:

Timeout exceeded in read_nonblocking().
<pexpect.spawn object at 0x7f007800d190>
version: 2.4 ($Revision: 516 $)
command: /usr/bin/ssh
args: ['/usr/bin/ssh', 'ssheth@jumpserver', '-q', '-oStrictHostKeyChecking=no', '-oUserKnownHostsFile=/dev/null', '-oPubkeyAuthentication=no']
searcher: searcher_re:
    0: re.compile("#")
buffer (last 100 chars): ssheth@jumpserver:~[ssheth@jumpserver ~]$ 
[ssheth@jumpserver ~]$ 
before (last 100 chars): ssheth@jumpserver:~[ssheth@jumpserver ~]$ 
[ssheth@jumpserver ~]$ 
after: <class 'pexpect.TIMEOUT'>
match: None
match_index: None
exitstatus: None
flag_eof: False
pid: 27286
child_fd: 91
closed: False
timeout: 2
delimiter: <class 'pexpect.EOF'>
logfile: None
logfile_read: None
logfile_send: None
maxread: 2000
ignorecase: False
searchwindowsize: None
delaybeforesend: 0.05
delayafterclose: 0.1
delayafterterminate: 0.1

Answer 1

Simplest answer is to open a port forwarding to the remote server.

This works best in bash, but you can subprocess, or whatever you prefer to run it through python.

Suppose the IPs are:

• jumpserver IP is 151.121.121.121
• finalserver IP is 10.1.2.3

Like follows

# Open a local port 13000 that will map through jumpserver and 
# connect to finalserver on port 22
ssh -L 13000:10.1.2.3:22 username@151.121.121.121
# Then open an ssh session to localhost:13000 (which will forward to the
# finalserver.com and run your command)
ssh username@localhost -p 13000 'rpm -qa | grep package'

Aside: looking at your expect script and remembering the old days. Python has some ssh wrappers. Paramiko is used with Fabric.

Answer 2

You can install jumpssh pypi using pip

pip install jumpssh