libssh2--ssh2实例

#include "libssh2_config.h"
#include<libssh2.h>
#include<libssh2_sftp.h>

上述为所包含必备头文件。

以下为定义的静态子串常量

const char *keyfile1 = "~/.ssh/id_rsa.pub";
const char *keyfile2 = "~/.ssh/id_rsa";
const char *username = "username";
const char *password = "password";

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;

 

连接到SSH2步骤：

（1）建立socket并连接到远程主机SSH2服务（22端口）；

（2）创建一个LIBSSH2_SESSION 实例并启动它。启动动作包括设置欢迎横幅、交换密钥并且设置加密、压缩和MAC层。

session = libssh2_session_init();   //创建一个会话实例
if(libssh2_session_handshake(session, sock))
{
  fprintf(stderr, "Failure establishing SSH session");
  return -1;
}

（3）认证：检查主机密钥指纹并检查可用的认证方式。

fingerprint = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1);
userauthlist = libssh2_userauth_list(session, username, strlen(username));
if(strstr(userauthlist, "password") != NULL)
{
  auth_pw |= 1;
}
if(strstr(userauthlist, "keyboad-interactive") != NULL)
{
  auth_pw |= 2;
}
if(strstr(userauthlist, "publickey") != NULL)
{
  auth_pw |= 4;
}

（4）如果在参数列表中设置了认证方式，则将认证方式设为命令中的方式（前提是该方式是通过上个步骤检测可用的）。

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;
  }
}

（5）根据上一步选定的认证方式开始认证。

if (auth_pw & 1) {
        /* We could authenticate via password */ 
        if (libssh2_userauth_password(session, username, password)) {

            fprintf(stderr, "\tAuthentication by password failed!\n");
            goto shutdown;
        } else {
            fprintf(stderr, "\tAuthentication by password succeeded.\n");
        }
    } else if (auth_pw & 2) {
        /* Or via keyboard-interactive */ 
        if (libssh2_userauth_keyboard_interactive(session, username,

                                                  &kbd_callback) ) {
            fprintf(stderr,
                "\tAuthentication by keyboard-interactive failed!\n");
            goto shutdown;
        } else {
            fprintf(stderr,
                "\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)) {
            fprintf(stderr, "\tAuthentication by public key failed!\n");
            goto shutdown;
        } else {
            fprintf(stderr, "\tAuthentication by public key succeeded.\n");
        }
    } else {
        fprintf(stderr, "No supported authentication methods found!\n");
        goto shutdown;
    }

（6）请求一个shell

if(!(channel = libssh2_channel_open_session(session)))

（7）设置一些环境变量，并上传给服务器

libssh2_channel_setenv(channel, "F00", "bar");

（8）请求一个vanilla的终端模拟。

libssh2_channel_request_pty(channel, "vanilla")

（9）在上一步请求的pty上开启SHELL。

libssh2_channel_shell(channel)

（10）至此，可以交互使用shell了

libssh2_channel_read();
libssh2_channel_read_stderr();
libssh2_channel_write();

libssh2_channel_write_stderr();


/* 打开或关闭阻塞模式 */

libssh2_channel_set_blocking();

/* 如果服务器发送EOF */

libssh2_channel_eof()返回非0；

/* 关闭channel */

libssh2_channel_close();

/* 释放一个channel */

libssh2_channel_free();

（11）ssh交互完成后，关闭会话并释放会话

libssh2_session_disconnect(session, "Normal Shutdown");
libssh2_session_free(session);

（12）关闭sock并退出libssh2

close(sock);
libssh2_exit();