Python Pexpect - SSH Timeout

[Nirmal]

Hi

I am using Pexpect module to make SSH connection but it is falling into Traceback and exits.
Any idea how to fix it .

I have tried multiple post that already exist in StackOverflow and other
forums but end up with no luck.

Traceback:

 <class 'pexpect.TIMEOUT'>
    Traceback (most recent call last):
      File "nirmal.hostlist.py", line 610, in <module>
        main()
      File "nirmal.hostlist.py", line 581, in main
        dataGrabber(ls5,ls5_leafs,username,password,enable_pass,ls5_cat_leafs,no_cat,no_l3_fw)
      File "nirmal.hostlist.py", line 428, in dataGrabber
        macs = macGrabber(child,switch)
      File "nirmal.hostlist.py", line 32, in macGrabber
        child.expect('.#')
      File "/usr/lib/python2.6/site-packages/pexpect.py", line 1311, in expect
        return self.expect_list(compiled_pattern_list, timeout, searchwindowsize)
      File "/usr/lib/python2.6/site-packages/pexpect.py", line 1325, in expect_list
        return self.expect_loop(searcher_re(pattern_list), timeout, searchwindowsize)
      File "/usr/lib/python2.6/site-packages/pexpect.py", line 1409, in expect_loop
        raise TIMEOUT (str(e) + '\n' + str(self))
    pexpect.TIMEOUT: Timeout exceeded in read_nonblocking().
    <pexpect.spawn object at 0xc6af90>
    version: 2.3 ($Revision: 399 $)
    command: /usr/bin/ssh
    args: ['/usr/bin/ssh', 'ng044806@ls5mm33-ci-red']
    searcher: searcher_re:
        0: re.compile(".#")
    buffer (last 100 chars):
    before (last 100 chars):
    after: <class 'pexpect.TIMEOUT'>
    match: None
    match_index: None
    exitstatus: None
    flag_eof: False
    pid: 56774
    child_fd: 3
    closed: False
    timeout: 30
    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

My code:

def ssh(hostname,username = 'nadda',password = 'nadda',enable_pass='nadda',cat = False):
        hostname = hostname.lower()
        pass_prompt = re.compile('.*assword:')
        need_key = re.compile('\s.*Are you sure you want to continue connecting \(yes\/no\)\?.',re.DOTALL)
        denied = re.compile('Permission denied, please try again\.')
        refused = re.compile('Connection refused by remote host')
        reset = re.compile('Connection reset by peer')
        count = 0
    
        if username is 'nadda' and password is 'nadda':
            username = raw_input('login as: ')
            password = getpass.getpass('Password:')
        print "connecting to " + hostname
        if cat is True:
            print ('ssh -t root@mgmtsrver "ssh %s@%s"' % (username,hostname))
            child = pexpect.spawn('ssh -t root@mgmtsrver "ssh %s@%s"' % (username,hostname))
            #ssh -t root@mgmtsrver "ssh bs04628@fs-it-sw-blue"
        else:
            child = pexpect.spawn('ssh ' + username + '@' + hostname)
        print 'connected to ' + hostname
        i = child.expect([need_key,'.*>',pass_prompt,pexpect.TIMEOUT,denied,refused,reset])
        if i==0:
            child.sendline('yes')
            print 'adding ssh key'
            child.expect(pass_prompt)
        else:
            print 'not adding ssh key'
    
        if i == 1 or cat is True:
            child.sendline(password)
            child.expect('.*>')
            child = enable(child,enable_pass)
        elif i == 2:
            if '-fw-' in hostname:
                child.sendline(enable_pass)
                child.expect('.*>')
                child = enable(child,enable_pass)
            else:
                child.sendline(password)
                child.sendline('term length 0')
                child.expect('.*#')
        elif i == 3:
            print 'SSH TIMED OUT ON ' + hostname
            exit()
        elif i == 4:
            print 'PERMISSION DENIED ON %s. Try re-running script with proper creds' % hostname
            child.close()
            exit()
        elif (i == 5 or i == 6) and count == 0:
            print 'CONNECTION REFUSED ON %s' % hostname
            print 'Will try to reconnect once in 5 seconds...'
            time.sleep(5)
            while count < 1:
                ssh(hostname,username,password,enable_pass)
                count += 1
        elif (i == 5 or i == 6) and count > 0:
            print 'Sorry, %s refused your connection more than once. ' \
                  'You\'ll have to re-run this script for %s' % (hostname, hostname[:3])
            exit()
        print '\n'
        return child,username,password

[wavic]

Test it in real using just bash and see what you get and why. Obviously pexpect doesn't read any output as I see in the documentation: https://pexpect.readthedocs.io/en/stable...exceptions

[Nirmal]

Got to know its getting failed here...

def macGrabber(child,switch,cat = False):
    try:
        if cat is False:
            child.expect('.#')
            child.sendline('sh mac address-table | no-more')
        else:
            child.sendline('sh mac address-table dynamic | i Gi')
        child.expect('.#', timeout=3000)
    except pexpect.TIMEOUT:
        print child.before,child.after
        child.close()
        raise
    macs = child.before
    child.close()
    macs = macs.splitlines()
    print('Connection to %s CLOSED' % switch)
    return macs

Can we set a retry here ?

[wavic]

Set it where exactly? The function has return statement and no while loop to keep it running. You can call again any function you want if some conditions are or aren't met.