Re: How can I open one channel and than execute several different commands in libssh?

[Jakub Jelen <jjelen@xxxxxxxxxx>]

On 2/7/21 2:17 AM, Bruno Buzzi Brassesco wrote:
> Hi,
> I do not have my notebook now.
> But you have to open a channel per each command.

Right,
or you will need to send separate commands in separate channel, because 
after ssh_channel_request_exec() shorthand, the underlying channel is 
closed.

The other possibility is to handle the IO for yourself and run the 
separate commands in a single shell as described in the following 
chapter of a tutorial:

https://api.libssh.org/stable/libssh_tutor_shell.html#opening_shell

Regards,
Jakub

> Regards,
> Bruno
>
> El sáb., 6 de febrero de 2021 22:14, 孙世龙 sunshilong 
> <sunshilong369@xxxxxxxxx <mailto:sunshilong369@xxxxxxxxx>> escribió:
>
>     Hi,list
>
>     For example i want to open one session and one channel and then
>     execute severeal different commands. I have InitializeSSHSession and
>     Initialize SSH channel methods can be seen below.
>
>     void Computer::InitializeSSHSession()
>       {
>       ssh_session remoteSSHSession = ssh_new();
>
>     if ( remoteSSHSession )
>     {
>          QString password = this->GetPassword();
>          QString remoteIP = this->GetIP();
>          QString userName = this->GetUserNameW();
>
>          ssh_options_set(remoteSSHSession, SSH_OPTIONS_HOST,
>     remoteIP.toStdString().c_str());
>          ssh_options_set(remoteSSHSession, SSH_OPTIONS_LOG_VERBOSITY,
>     &sessionVerbosity);
>          ssh_options_set(remoteSSHSession, SSH_OPTIONS_PORT, &sessionPort);
>          ssh_options_set(remoteSSHSession, SSH_OPTIONS_USER,
>     userName.toStdString().c_str());
>
>          int remoteConnection = ssh_connect(remoteSSHSession);
>          if ( remoteConnection == SSH_OK )
>          {
>              int authenticateControl =
>     ssh_userauth_password(remoteSSHSession, NULL,
>     password.toStdString().c_str());
>              if ( authenticateControl == SSH_AUTH_SUCCESS )
>              {
>                  InitializeSSHChannel(remoteSSHSession);
>              }
>              else
>              {
>                  remoteSSHSession = NULL;
>              }
>          }
>          else
>          {
>              remoteSSHSession = NULL;
>          }
>     }
>     else
>     {
>           remoteSSHChannel = NULL;
>     }
>     }
>
>     void Computer::InitializeSSHChannel(ssh_session remoteSSHSession)
>     {
>     remoteSSHChannel = ssh_channel_new(remoteSSHSession);
>
>     if ( remoteSSHChannel )
>     {
>          int channelControl = ssh_channel_open_session(remoteSSHChannel);
>          if ( channelControl != SSH_OK )
>          {
>              EventLogger::LogMessage(true, "SSH channel sesssion failed!");
>              ssh_channel_free(remoteSSHChannel);
>          }
>     }
>       }
>
>     And in the main, I am initializing session and getting channel like
>     this:
>
>       InitializeSSHSession();
>       ssh_channel channel = GetSSHChannel();
>
>     And then
>
>        int rc = ssh_channel_request_exec(channel, "ls -l");
>
>     It is okay it is executed correctly but when i want to execute another
>     command it is not execute, I should return the beginning of process
>     first initialize session and getting channel again.
>
>     It is not good solution for every command. Is it possible to do that
>     once initialize session than use it again and again for every command
>     ?


--
Jakub Jelen
Senior Software Engineer
Crypto Team, Security Engineering
Red Hat, Inc.