ssh_auth.c

/*
 * MIT License
 *
 * Copyright (c) 2018 Lewis Van Winkle
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "chap11.h"

int main(int argc, char *argv[])
{
    if (argc < 4) {
        fprintf(stderr, "Usage: ssh_auth hostname port user\n");
        return 1;
    }
    const char *hostname = argv[1];
    int port = atol(argv[2]);
    const char *user = argv[3];


    ssh_session ssh = ssh_new();
    if (!ssh) {
        fprintf(stderr, "ssh_new() failed.\n");
        return 1;
    }

    ssh_options_set(ssh, SSH_OPTIONS_HOST, hostname);
    ssh_options_set(ssh, SSH_OPTIONS_PORT, &port);
    ssh_options_set(ssh, SSH_OPTIONS_USER, user);

    int ret = ssh_connect(ssh);
    if (ret != SSH_OK) {
        fprintf(stderr, "ssh_connect() failed.\n%s\n", ssh_get_error(ssh));
        return -1;
    }

    printf("Connected to %s on port %d.\n", hostname, port);

    printf("Banner:\n%s\n", ssh_get_serverbanner(ssh));



    ssh_key key;
    if (ssh_get_server_publickey(ssh, &key) != SSH_OK) {
        fprintf(stderr, "ssh_get_server_publickey() failed.\n%s\n",
                ssh_get_error(ssh));
        return -1;
    }

    unsigned char *hash;
    size_t hash_len;
    if (ssh_get_publickey_hash(key, SSH_PUBLICKEY_HASH_SHA1,
                &hash, &hash_len) != SSH_OK) {
        fprintf(stderr, "ssh_get_publickey_hash() failed.\n%s\n",
                ssh_get_error(ssh));
        return -1;
    }

    printf("Host public key hash:\n");
    ssh_print_hash(SSH_PUBLICKEY_HASH_SHA1, hash, hash_len);

    ssh_clean_pubkey_hash(&hash);
    ssh_key_free(key);




    printf("Checking ssh_session_is_known_server()\n");
    enum ssh_known_hosts_e known = ssh_session_is_known_server(ssh);
    switch (known) {
        case SSH_KNOWN_HOSTS_OK: printf("Host Known.\n"); break;

        case SSH_KNOWN_HOSTS_CHANGED: printf("Host Changed.\n"); break;
        case SSH_KNOWN_HOSTS_OTHER: printf("Host Other.\n"); break;
        case SSH_KNOWN_HOSTS_UNKNOWN: printf("Host Unknown.\n"); break;
        case SSH_KNOWN_HOSTS_NOT_FOUND: printf("No host file.\n"); break;

        case SSH_KNOWN_HOSTS_ERROR:
            printf("Host error. %s\n", ssh_get_error(ssh)); return 1;

        default: printf("Error. Known: %d\n", known); return 1;
    }



    if (known == SSH_KNOWN_HOSTS_CHANGED ||
            known == SSH_KNOWN_HOSTS_OTHER ||
            known == SSH_KNOWN_HOSTS_UNKNOWN ||
            known == SSH_KNOWN_HOSTS_NOT_FOUND) {
        printf("Do you want to accept and remember this host? Y/N\n");
        char answer[10];
        fgets(answer, sizeof(answer), stdin);
        if (answer[0] != 'Y' && answer[0] != 'y') {
            return 0;
        }

        ssh_session_update_known_hosts(ssh);
    }



    printf("Password: ");
    char password[128];
    fgets(password, sizeof(password), stdin);
    password[strlen(password)-1] = 0;

    if (ssh_userauth_password(ssh, 0, password) != SSH_AUTH_SUCCESS)
    {
        fprintf(stderr, "ssh_userauth_password() failed.\n%s\n",
                ssh_get_error(ssh));
        return 0;
    } else {
        printf("Authentication successful!\n");
    }


    ssh_disconnect(ssh);
    ssh_free(ssh);

    return 0;
}