Re: ssh_channel_open_session only works the first time called

["Thorsten R." <libssh.org_ml@xxxxxxxxxxxxxxxxxxxx>]

On 11/2/21 15:46, Jakub Jelen wrote:
> Hi,
> does your Cisco switch support more channels? You can try it for
> example with openssh with connection multiplexing using
> ControlMaster/ControlPath.

That's an interesting point. Did not know that multiplexing is possible.
But this is what I got:

First terminal
==============
tr@LinuxMint19:~/$ ssh -o ControlMaster=yes -o 
ControlPath=~/.ssh/control-%h_%p_%r admin@192.168.4.219
Password: ************
gwswitch1#

Second terminal
===============
tr@LinuxMint19:~/$ ssh -o ControlPath=~/.ssh/control-%h_%p_%r 
admin@192.168.4.219
mux_client_request_session: session request failed: Session open refused 
by peer
Password: ************
gwswitch1#

Output on first terminal after second terminal connects:
gwswitch1#channel 3: open failed: resource shortage:
gwswitch1#

It seems that multiplexing is not possible on Cisco switches.
But now I am a little bit confused. I thought that calling

ssh_channel_close(channel);
ssh_channel_free(channel);

closes the shell and the session in a way that I can open a new one if 
needed.
What is the right way to open a SSH connection, open a terminal/shell, 
execute a few commands in it with

ssh_channel_write()
ssh_channel_read_nonblocking()

and close the shell without losing the connection?

> comes from an error writing some packet. Can you step through that
> part of the code for example with gdb to see what is failing where. I

I am using a compiled libssh library. For that I cannot debug the libssh 
code. :(

> Also, the important question is which libssh version are you using? Is
> it up to date?

I am using version 0.9.6.

Thorsten