C++ Retrieve data via SSH using libssh libary failed - c++

Question

I'm trying to get the output of the command 'df' which I'll replace later, from a remote server:
#include <libssh/libssh.h>
#include <stdlib.h>
#include <stdio.h>
int main()
{
ssh_session my_ssh_session;
int rc;
ssh_channel channel;
char buffer[256];
int nbytes;
int port = 22;
my_ssh_session = ssh_new();
if (my_ssh_session == NULL)
exit(-1);
ssh_options_set(my_ssh_session, SSH_OPTIONS_HOST, "192.168.2.2");
ssh_options_set(my_ssh_session, SSH_OPTIONS_PORT, &port);
rc = ssh_connect(my_ssh_session);
if (rc != SSH_OK)
{
fprintf(stderr, "Failed %s\n",
ssh_get_error(my_ssh_session));
exit(-1);
}
channel = ssh_channel_new(my_ssh_session);
if (channel == NULL)
return SSH_ERROR;
rc = ssh_channel_open_session(channel);
if (rc != SSH_OK)
{
ssh_channel_free(channel);
return rc;
}
rc = ssh_channel_request_exec(channel, "df");
if (rc != SSH_OK)
{
ssh_channel_close(channel);
ssh_channel_free(channel);
return rc;
}
nbytes = ssh_channel_read(channel, buffer, sizeof(buffer), 0);
while (nbytes > 0)
{
if (write(1, buffer, nbytes) != nbytes)
{
ssh_channel_close(channel);
ssh_channel_free(channel);
return SSH_ERROR;
}
nbytes = ssh_channel_read(channel, buffer, sizeof(buffer), 0);
}
if (nbytes < 0)
{
ssh_channel_close(channel);
ssh_channel_free(channel);
return SSH_ERROR;
}
ssh_channel_send_eof(channel);
ssh_channel_close(channel);
ssh_channel_free(channel);
return SSH_OK;
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
}
The compiler didn't show any errors,
but there were no results when I run the program,
I checked the syslog of the remote server and I found the following line:
sshd[12794]: dispatch_protocol_error: type 90 seq 3
Please advise what could be the problem,
Thank you.

Answer 1

It seems like you are trying to get to the remote server without functions of host authentification (e.g. checking information from /.ssh/known_hosts) and user authentificationa through public keys or password. You should place these two functions after the
if (rc != SSH_OK)
{
fprintf(stderr, "Failed %s\n", ssh_get_error(my_ssh_session));
exit(-1);
}
Look through the chapters 1 and 2 in libssh tutorial.