MarketSquare / MarketSquare/SSHLibrary

some devices do not permit connection sharing

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Dominant language
Python
Stars
167
Forks
145
PR merge metrics
No merged PRs in 30d

Description

Ex: Cisco NCS 5500 64bit

Some devices we use Robot with do not permit connection sharing as replicated via OpenSSH client https://unix.stackexchange.com/questions/33557/using-an-already-established-ssh-channel

As SSHLibrary makes use by sub-channeling the already established ssh connection via the `Execute Command` directive in an effort to improve speed, on the NCS 5500 (which i suspect this is actually a bug Cisco needs to address, as this works flawlessly on all other Cisco devices), the end result is we are able to open the second channel and run our command but on exit it causes the primary channel to also close.

While support for SSH Channeling is outlined by rfc4254 5.x and loosely supported by the NCS 5500 64bit, the handling of the Channel closure causes the session to close prior to the initial channel closing is in direct conflict with rfc4254 5.3

I am creating this issue to handle the following: to determine if there is any interest in having a mechanism for disabling the use of multiple channels, and to make all aware of this odd issue.

`Write` and `Read Until` functions are possible up until a `Execute Command` is ran which returns the CLI output as well as an EOF error. All future SSH operations will fail.

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by locating the SSHLibrary implementation of the `Execute Command` directive and its multiple-channel handling, then reproduce the failure described for Cisco NCS 5500 64bit. Done means determining whether disabling connection sharing is feasible and documenting or implementing a mechanism that preserves the primary channel after command execution.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
networking
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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