How to do double authentication using libssh module? - c

Question

My SSH server uses double authtication. I do not know how its implemented. But initially its asks for a password, then again asks for another password to login to a separate console which is different from usual control.
My code is similar to the example code shown in the documentations,
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <libssh/libssh.h>
int main(int argc, char * argv[])
{
ssh_session my_ssh_session = ssh_new();
int rc;
char * password;
char * username = "admin";
// Check if ssh session exists.
if(my_ssh_session == NULL)
{
exit(-1);
}
ssh_options_set(my_ssh_session, SSH_OPTIONS_HOST, "x.x.x.x");
rc = ssh_connect(my_ssh_session);
if (rc != SSH_OK)
{
fprintf(stderr, "Error Connecting to Server: %s.\n", ssh_get_error(my_ssh_session));
exit(-1);
}
password = getpass("Password: ");
rc = ssh_userauth_password(my_ssh_session, username, password);
if (rc != SSH_AUTH_SUCCESS)
{
fprintf(stderr, "ERROR Authenticating: %s.\n", ssh_get_error(my_ssh_session));
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
}
else
{
printf("Authentication Successful.\n");
}
ssh_free(my_ssh_session);
}
How do i implement a double authtication in this ? can you kindly help me out ?

Answer 1

What version of
libssh do you have?
"versions 0.5.1 and above have a logical error in the handling of a SSH_MSG_NEWKEYS and SSH_MSG_KEXDH_REPLY package. A detected error did not set the session into the error state correctly and further processed the packet which leads to a null pointer dereference. This is the packet after the initial key exchange and doesn’t require authentication."
Ref libssh