Issue

While attempting to get a libssh server running in linux, I am getting caught at the Error Listening to socket: Failed to import private RSA host key. I was using two examples as references. https://github.com/substack/libssh/blob/master/examples/samplesshd.c and https://github.com/PeteMo/sshpot/blob/master/main.c. But the latter reference mentioned using the public key, not private in the readme which has me confused.

I am still a tenderfoot C practitioner so I am very sure that I am doing something incorrectly. Maybe even asm himself(creator I believe) will grace me with a quick tip or two. Here is my code:

#include <libssh/libssh.h>
#include <libssh/server.h>  
#include <libssh/callbacks.h>
#include <libssh/legacy.h>
#include <stdlib.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>

#define SSHD_USER "user"
#define SSHD_PASSWORD "password"
#define KEYS_FILE "./ssh_host_rsa_key" 
/*#ifndef KEYS_FILE
#define KEYS_FILE
#else
#endif*/

static int auth_password(char *user, char *password)
{
    if(strcmp(user, SSHD_USER)) {
        return 0;
    } else {
        return 1;
    }

    if(strcmp(password, SSHD_PASSWORD)) {
        return 0;
    } else {
        return 1;
    }

    return 0;    
}


int main()
{
    ssh_bind sshbind = ssh_bind_new();
    ssh_session my_session = ssh_new();

    int port = 900;
    char *address = "127.0.0.1";

    ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_BINDADDR, address);
    ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_BINDPORT_STR, &port);
    ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_HOSTKEY, "ssh-rsa");
    ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_RSAKEY, KEYS_FILE);

    if (ssh_bind_listen(sshbind) < 0) {
        printf("Error listening to socket: %s\n", ssh_get_error(sshbind));
        return 1;
    }

    /* Loop, waiting for and handling connection attempts. */
    while(1) {
        if (ssh_bind_accept(sshbind, my_session) == SSH_ERROR) {
            fprintf(stderr, "Error accepting a connection: `%s'.\n",ssh_get_error(sshbind));

            return -1;
        } else {
            printf("Accepted a connection.\n");
        }

        switch (fork()) {
            case -1:
                fprintf(stderr,"Fork returned error: `%d'.\n",-1);
                exit(-1);

            case 0:
                exit(auth_password(SSHD_USER, SSHD_PASSWORD));

            default:
                break;
        }
    }

    return 0;
}

Error Listening to socket: Failed to import private RSA host key

I also tried using the content of ssh_host_rsa_key directly as a variable in several ways. The official reference doc has this line

ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_RSAKEY, KEYS_FOLDER "ssh_host_rsa_key")

I used this too along with the #define KEYS_FILE if else block that I commented out when I tried a different approach. Right now my private key is in the same directory as my server(out of frustration).

Any tips or hints greatly appreciated!

Solution

In the unlikely case that anyone out there ever has this issue, my solution was to generate new ssh keys and link my code to those. For whatever reason the keys that I generated the first time did not work but removing them and using a fresh pair worked. No one will ever read these words.

Answered By - DocSpiegel

Answer Checked By - Robin (WPSolving Admin)

Friday, October 28, 2022

[SOLVED] libssh server failed to import private RSA host key

Issue

Solution