使用 libssh2 连接到远程服务器

/*
 * Sample showing how to do SSH2 connect.
 *
 * The sample code has default values for host name, user name, password
 * and path to copy, but you can specify them on the command line like:
 *
 * "ssh2 host user password [-p|-i|-k]"
 */
  
#include "libssh2_config.h"
#include <libssh2.h>
#include <libssh2_sftp.h>
  
#ifdef HAVE_WINDOWS_H
#include <windows.h>
#endif
#ifdef HAVE_WINSOCK2_H
#include <winsock2.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
  
#include <sys/types.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <ctype.h>
  
  
const char *keyfile1="~/.ssh/id_rsa.pub";
const char *keyfile2="~/.ssh/id_rsa";
const char *username="username";
const char *password="password";
  
  
static void kbd_callback(const char *name, int name_len,
                         const char *instruction, int instruction_len,
                         int num_prompts,
                         const LIBSSH2_USERAUTH_KBDINT_PROMPT *prompts,
                         LIBSSH2_USERAUTH_KBDINT_RESPONSE *responses,
                         void **abstract)
{
    (void)name;
    (void)name_len;
    (void)instruction;
    (void)instruction_len;
    if (num_prompts == 1) {
        responses[0].text = strdup(password);
        responses[0].length = strlen(password);
    }
    (void)prompts;
    (void)abstract;
} /* kbd_callback */
  
  
int main(int argc, char *argv[])
{
    unsigned long hostaddr;
    int rc, sock, i, auth_pw = 0;
    struct sockaddr_in sin;
    const char *fingerprint;
    char *userauthlist;
    LIBSSH2_SESSION *session;
    LIBSSH2_CHANNEL *channel;
#ifdef WIN32
    WSADATA wsadata;
  
    WSAStartup(MAKEWORD(2,0), &wsadata);
#endif
  
    if (argc > 1) {
        hostaddr = inet_addr(argv[1]);
    } else {
        hostaddr = htonl(0x7F000001);
    }
  
    if(argc > 2) {
        username = argv[2];
    }
    if(argc > 3) {
        password = argv[3];
    }
  
    rc = libssh2_init (0);
 
    if (rc != 0) {
        fprintf (stderr, "libssh2 initialization failed (%d)\n", rc);
        return 1;
    }
  
    /* Ultra basic "connect to port 22 on localhost".  Your code is
     * responsible for creating the socket establishing the connection
     */
    sock = socket(AF_INET, SOCK_STREAM, 0);
  
    sin.sin_family = AF_INET;
    sin.sin_port = htons(22);
    sin.sin_addr.s_addr = hostaddr;
    if (connect(sock, (struct sockaddr*)(&sin),
                sizeof(struct sockaddr_in)) != 0) {
        fprintf(stderr, "failed to connect!\n");
        return -1;
    }
  
    /* Create a session instance and start it up. This will trade welcome
     * banners, exchange keys, and setup crypto, compression, and MAC layers
     */
    session = libssh2_session_init();
 
    if (libssh2_session_handshake(session, sock)) {
 
        fprintf(stderr, "Failure establishing SSH session\n");
        return -1;
    }
  
    /* At this point we havn't authenticated. The first thing to do is check
     * the hostkey's fingerprint against our known hosts Your app may have it
     * hard coded, may go to a file, may present it to the user, that's your
     * call
     */
    fingerprint = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1);
 
    printf("Fingerprint: ");
    for(i = 0; i < 20; i++) {
        printf("%02X ", (unsigned char)fingerprint[i]);
    }
    printf("\n");
  
    /* check what authentication methods are available */
    userauthlist = libssh2_userauth_list(session, username, strlen(username));
 
    printf("Authentication methods: %s\n", userauthlist);
    if (strstr(userauthlist, "password") != NULL) {
        auth_pw |= 1;
    }
    if (strstr(userauthlist, "keyboard-interactive") != NULL) {
        auth_pw |= 2;
    }
    if (strstr(userauthlist, "publickey") != NULL) {
        auth_pw |= 4;
    }
  
    /* if we got an 4. argument we set this option if supported */
    if(argc > 4) {
        if ((auth_pw & 1) && !strcasecmp(argv[4], "-p")) {
            auth_pw = 1;
        }
        if ((auth_pw & 2) && !strcasecmp(argv[4], "-i")) {
            auth_pw = 2;
        }
        if ((auth_pw & 4) && !strcasecmp(argv[4], "-k")) {
            auth_pw = 4;
        }
    }
  
    if (auth_pw & 1) {
        /* We could authenticate via password */
        if (libssh2_userauth_password(session, username, password)) {
 
            printf("\tAuthentication by password failed!\n");
            goto shutdown;
        } else {
            printf("\tAuthentication by password succeeded.\n");
        }
    } else if (auth_pw & 2) {
        /* Or via keyboard-interactive */
        if (libssh2_userauth_keyboard_interactive(session, username,
 
                                                  &kbd_callback) ) {
            printf("\tAuthentication by keyboard-interactive failed!\n");
            goto shutdown;
        } else {
            printf("\tAuthentication by keyboard-interactive succeeded.\n");
        }
    } else if (auth_pw & 4) {
        /* Or by public key */
        if (libssh2_userauth_publickey_fromfile(session, username, keyfile1,
 
                                                keyfile2, password)) {
            printf("\tAuthentication by public key failed!\n");
            goto shutdown;
        } else {
            printf("\tAuthentication by public key succeeded.\n");
        }
    } else {
        printf("No supported authentication methods found!\n");
        goto shutdown;
    }
  
    /* Request a shell */
    if (!(channel = libssh2_channel_open_session(session))) {
 
        fprintf(stderr, "Unable to open a session\n");
        goto shutdown;
    }
  
    /* Some environment variables may be set,
     * It's up to the server which ones it'll allow though
     */
    libssh2_channel_setenv(channel, "FOO", "bar");
 
  
    /* Request a terminal with 'vanilla' terminal emulation
     * See /etc/termcap for more options
     */
    if (libssh2_channel_request_pty(channel, "vanilla")) {
 
        fprintf(stderr, "Failed requesting pty\n");
        goto skip_shell;
    }
  
    /* Open a SHELL on that pty */
    if (libssh2_channel_shell(channel)) {
 
        fprintf(stderr, "Unable to request shell on allocated pty\n");
        goto shutdown;
    }
  
    /* At this point the shell can be interacted with using
     * libssh2_channel_read()
     * libssh2_channel_read_stderr()
     * libssh2_channel_write()
     * libssh2_channel_write_stderr()
     *
     * Blocking mode may be (en|dis)abled with: libssh2_channel_set_blocking()
     * If the server send EOF, libssh2_channel_eof() will return non-0
     * To send EOF to the server use: libssh2_channel_send_eof()
     * A channel can be closed with: libssh2_channel_close()
     * A channel can be freed with: libssh2_channel_free()
     */
  
  skip_shell:
    if (channel) {
        libssh2_channel_free(channel);
 
        channel = NULL;
    }
  
    /* Other channel types are supported via:
     * libssh2_scp_send()
     * libssh2_scp_recv()
     * libssh2_channel_direct_tcpip()
     */
  
  shutdown:
  
    libssh2_session_disconnect(session,
 
                               "Normal Shutdown, Thank you for playing");
    libssh2_session_free(session);
 
  
#ifdef WIN32
    closesocket(sock);
#else
    close(sock);
#endif
    printf("all done!\n");
  
    libssh2_exit();
 
  
    return 0;
}

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