failing to execute consecutive commands on a remote host

[mohsen1565]

After testing, I realized that, every time a command is executed on a remote server the session needs to be closed and reopened before running the next command.
Can you please investigate?

[t-cas]

this is not the expected behavior, a session remains opened until:

• you explicitely call close on SSHSession instance
• SSHSession instance is garbage collected
• underlying ssh connection is closed by remote host (so SSHSession becomes inactive)

see several tests in which we call multiple successive run_cmd on a single SSHSession instance: https://github.com/AmadeusITGroup/JumpSSH/blob/master/tests/test_session.py#L127

If you are not in one of those cases, please provide a code example having this issue so that we can troubleshoot further.

[mohsen1565]

Hi. Thank you for your quick response. Consider the following code: from jumpssh import SSHSession jumHostPassword='MyPass' jumHostUsername='MyUser' EndDeviceUsename='MyUser' EndDevicePassword='MyPass' gateway_session = SSHSession('MyHost', jumHostUsername, private_key_file= '/home/d806848/.ssh/Identity_rsa', password='Mypassphrase').open() remote_session = gateway_session.get_remote_session('MyRouter', username=EndDeviceUsename, password=EndDevicePassword) print(remote_session.get_cmd_output('show interfaces Te3/6.319 | i bia')) #remote_session.close() #remote_session = gateway_session.get_remote_session('MyRouter', username=EndDeviceUsename, password=EndDevicePassword) print(remote_session.get_cmd_output('show standby Te3/6.319 | i Active virtual MAC')) If I run the code, only the first print command will execute: Hardware is C7600 10Gb 802.3, address is 0024.142c.96c0 (bia 0024.142c.96c0) Traceback (most recent call last): File "test.py", line 11, in <module> print(remote_session.get_cmd_output('show standby Te3/6.319 | i Active virtual MAC')) File "/home/d806848/mpls_impv/mplsAddrEnv/lib/python3.6/site-packages/jumpssh/session.py", line 407, in get_cmd_output return self.run_cmd(cmd=cmd, **kwargs).output File "/home/d806848/mpls_impv/mplsAddrEnv/lib/python3.6/site-packages/jumpssh/session.py", line 284, in run_cmd channel = self.ssh_transport.open_session() File "/home/d806848/mpls_impv/mplsAddrEnv/lib/python3.6/site-packages/paramiko/transport.py", line 767, in open_session timeout=timeout) File "/home/d806848/mpls_impv/mplsAddrEnv/lib/python3.6/site-packages/paramiko/transport.py", line 891, in open_channel raise e File "/home/d806848/mpls_impv/mplsAddrEnv/lib/python3.6/site-packages/paramiko/transport.py", line 1909, in run ptype, m = self.packetizer.read_message() File "/home/d806848/mpls_impv/mplsAddrEnv/lib/python3.6/site-packages/paramiko/packet.py", line 426, in read_message header = self.read_all(self.__block_size_in, check_rekey=True) File "/home/d806848/mpls_impv/mplsAddrEnv/lib/python3.6/site-packages/paramiko/packet.py", line 276, in read_all raise EOFError() EOFError However if I close and reestablish the connection to the remote host, it will then start to work: from jumpssh import SSHSession jumHostPassword='MyPass' jumHostUsername='MyUser' EndDeviceUsename='MyUser' EndDevicePassword='MyPass' gateway_session = SSHSession('MyHost', jumHostUsername, private_key_file= '/home/d806848/.ssh/Identity_rsa', password='MyPassphrase').open() remote_session = gateway_session.get_remote_session('MyRouter', username=EndDeviceUsename, password=EndDevicePassword) print(remote_session.get_cmd_output('show interfaces Te3/6.319 | i bia')) remote_session.close() remote_session = gateway_session.get_remote_session('MyRouter', username=EndDeviceUsename, password=EndDevicePassword) print(remote_session.get_cmd_output('show standby Te3/6.319 | i Active virtual MAC')) Which runs fine: (mplsAddrEnv) d806848@nebula-07:~/mpls_impv$ python test.py Hardware is C7600 10Gb 802.3, address is 0024.142c.96c0 (bia 0024.142c.96c0) Active virtual MAC address is 0000.0c07.ace0 (mplsAddrEnv) d806848@nebula-07 :~/mpls_impv$ I'm not sure why it does not allow consecutive execution of commands. Regards,

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On Fri, Nov 9, 2018 at 7:03 PM Thibaud Castaing ***@***.***> wrote: this is not the expected behavior, a session remains opened until: - you explicitely call close on SSHSession instance - SSHSession instance is garbage collected - underlying ssh connection is closed by remote host (so SSHSession becomes inactive) see several tests in which we call multiple successive run_cmd on a single SSHSession instance: https://github.com/AmadeusITGroup/JumpSSH/blob/master/tests/test_session.py#L127 If you are not in one of those cases, please provide a code example having this issue so that we can troubleshoot further. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#42 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AHqhBCHHy2Dw1XdJRKDxD1wwNYg48ttkks5utTa1gaJpZM4YV-SY> .

[t-cas]

From what I can see looking a bit around, this seems to be a common issue with Cisco devices that apparently only allow one exec command execution per connection:

• https://stackoverflow.com/questions/48229181/paramiko-exec-command-with-multiple-commands-on-cisco-router-not-providing-any-o
• https://stackoverflow.com/questions/8151107/paramiko-failed-to-re-use-ssh-session-when-connecting-to-cisco-c2960-switcher

if you don't have any issue with the latency introduced when reopening the session for each command, I think it will be the easiest approach.