How to link .so file to a cpp program - c++

Question

I have libssh2.so.1.0.1(.so) binary on my local machine and I don't have any header files present on my machine.
This is the basic ssh program I have been trying to connect to my server through ssh protocol.
Reference: How to establish a simple ssh connection with c++
Now I am unable to link library (libssh2.so.1.0.1) to the below sample program.
Following is the sample program I have written and followed by errors.
sshsample.cpp:
#include <stdlib.h>
#include <stdio.h>
int main()
{
ssh_session my_ssh_session;
int rc;
int port = 22;
int verbosity = SSH_LOG_PROTOCOL;
char *password;
// Open session and set options
my_ssh_session = ssh_new();
if (my_ssh_session == NULL)
exit(-1);
ssh_options_set(my_ssh_session, SSH_OPTIONS_HOST, "192.168.1.6");
ssh_options_set(my_ssh_session, SSH_OPTIONS_USER, "john");
ssh_options_set(my_ssh_session, SSH_OPTIONS_LOG_VERBOSITY, &verbosity);
// Connect to server
rc = ssh_connect(my_ssh_session);
if (rc != SSH_OK)
{
fprintf(stderr, "Error: %s\n", ssh_get_error(my_ssh_session));
ssh_free(my_ssh_session);
exit(-1);
}
// Authenticate ourselves
password = "pass";
rc = ssh_userauth_password(my_ssh_session, NULL, password);
if (rc != SSH_AUTH_SUCCESS)
{
fprintf(stderr, "Error authenticating with password: %s\n",
ssh_get_error(my_ssh_session));
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
exit(-1);
}
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
}
I have compiled the above file with below command
g++ -L. -llibssh2 -o main sshsample.cpp
but I get the following error
sshsample.cpp: In function 'int main()':
sshsample.cpp:8: error: 'ssh_session' was not declared in this scope
sshsample.cpp:8: error: expected `;' before 'my_ssh_session'
sshsample.cpp:11: error: 'SSH_LOG_PROTOCOL' was not declared in this scope
sshsample.cpp:14: error: 'my_ssh_session' was not declared in this scope
sshsample.cpp:14: error: 'ssh_new' was not declared in this scope
Any suggestions/help would be of great use
Thanks in advance ...

Answer 1

You need to include the libssh2 header file into your compilation units where ssh APIs are invoked. You cannot expect the compiler to resolve what an ssh_session is without this. If you have the library properly installed, you should have access to the header files to invoke it.
#include <libssh2.h>
Edit: Honestly the APIs you are using in your example belong to the original libssh library I don't see anything in your example that would need to link with libssh2.
#include <libssh/libssh.h>