286 lines
8.8 KiB
C
286 lines
8.8 KiB
C
#include "reverse-tunnel.h"
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#include <pthread.h>
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#include <libssh2.h>
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#include <netinet/in.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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const char *keyfile1 = "/home/aixiao/.ssh/id_rsa.pub";
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const char *keyfile2 = "/home/aixiao/.ssh/id_rsa";
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const char *username = "aixiao";
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const char *password = "12345";
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const char *server_ip = "127.0.0.1";
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const char *remote_listenhost = "0.0.0.0"; /* 由远程服务器解析 */
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int remote_wantport = 33;
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int remote_listenport;
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const char *local_destip = "0.0.0.0";
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int local_destport = 22;
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struct tunnel_args {
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LIBSSH2_CHANNEL *channel;
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LIBSSH2_SESSION *session;
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};
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enum {
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AUTH_NONE = 0,
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AUTH_PASSWORD,
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AUTH_PUBLICKEY
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};
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int forward_tunnel(LIBSSH2_SESSION *session, LIBSSH2_CHANNEL *channel)
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{
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int i, rc = 0;
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struct sockaddr_in sin;
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fd_set fds;
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struct timeval tv;
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ssize_t len, wr;
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char buf[16384];
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int forwardsock = -1;
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fprintf(stdout, "接受到远程连接。连接到本地服务器 %s:%d\n", local_destip, local_destport);
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forwardsock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
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if (forwardsock == -1) {
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fprintf(stderr, "打开socket错误\n");
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goto shutdown;
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}
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sin.sin_family = AF_INET;
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sin.sin_port = htons(local_destport);
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if (INADDR_NONE == (sin.sin_addr.s_addr = inet_addr(local_destip))) {
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fprintf(stderr, "无效的本地IP地址\n");
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goto shutdown;
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}
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if (-1 == connect(forwardsock, (struct sockaddr *)&sin, sizeof(struct sockaddr_in))) {
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fprintf(stderr, "连接失败！\n");
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goto shutdown;
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}
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fprintf(stdout, "将连接从远程 %s:%d 转发到本地 %s:%d\n", remote_listenhost, remote_listenport, local_destip, local_destport);
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/* 设置会话为非阻塞IO */
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libssh2_session_set_blocking(session, 0);
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while (1) {
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FD_ZERO(&fds);
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FD_SET(forwardsock, &fds);
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tv.tv_sec = 0;
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tv.tv_usec = 100000;
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rc = select(forwardsock + 1, &fds, NULL, NULL, &tv);
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if (-1 == rc) {
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fprintf(stderr, "socket未准备好！\n");
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goto shutdown;
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}
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if (rc && FD_ISSET(forwardsock, &fds)) {
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len = recv(forwardsock, buf, sizeof(buf), 0);
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if (len < 0) {
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fprintf(stderr, "从forwardsock读取时出错！\n");
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goto shutdown;
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} else if (0 == len) {
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fprintf(stderr, "本地服务器 %s:%d 断开连接！\n", local_destip, local_destport);
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goto shutdown;
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}
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wr = 0;
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do {
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i = libssh2_channel_write(channel, buf, len);
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if (i < 0) {
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fprintf(stderr, "在SSH通道上写入时出错: %d\n", i);
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goto shutdown;
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}
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wr += i;
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} while (i > 0 && wr < len);
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}
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while (1) {
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len = libssh2_channel_read(channel, buf, sizeof(buf));
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if (LIBSSH2_ERROR_EAGAIN == len)
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break;
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else if (len < 0) {
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fprintf(stderr, "从SSH通道读取时出错: %d\n", (int)len);
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goto shutdown;
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}
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wr = 0;
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while (wr < len) {
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i = send(forwardsock, buf + wr, len - wr, 0);
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if (i <= 0) {
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fprintf(stderr, "在forwardsock上写入时出错！\n");
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goto shutdown;
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}
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wr += i;
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}
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if (libssh2_channel_eof(channel)) {
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fprintf(stderr, "远程客户端 %s:%d 断开连接！\n", remote_listenhost, remote_listenport);
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goto shutdown;
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}
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}
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}
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shutdown:
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close(forwardsock);
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/* 将会话设置回阻塞IO */
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libssh2_session_set_blocking(session, 1);
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return rc;
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}
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void *handle_tunnel(void *arg)
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{
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LIBSSH2_CHANNEL *channel = ((struct tunnel_args *)arg)->channel;
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LIBSSH2_SESSION *session = ((struct tunnel_args *)arg)->session;
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forward_tunnel(session, channel);
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libssh2_channel_free(channel);
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free(arg); // 释放为参数分配的内存
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return NULL;
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}
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int main(int argc, char *argv[])
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{
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int rc, i, auth = AUTH_NONE;
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struct sockaddr_in sin;
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const char *fingerprint;
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char *userauthlist;
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LIBSSH2_SESSION *session;
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LIBSSH2_LISTENER *listener = NULL;
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LIBSSH2_CHANNEL *channel = NULL;
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int sock = -1;
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if (argc > 1)
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server_ip = argv[1];
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if (argc > 2)
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username = argv[2];
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if (argc > 3)
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password = argv[3];
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if (argc > 4)
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remote_listenhost = argv[4];
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if (argc > 5)
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remote_wantport = atoi(argv[5]);
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if (argc > 6)
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local_destip = argv[6];
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if (argc > 7)
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local_destport = atoi(argv[7]);
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rc = libssh2_init(0);
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if (rc != 0) {
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fprintf(stderr, "libssh2初始化失败 (%d)\n", rc);
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return 1;
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}
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/* 连接到SSH服务器 */
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sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
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if (sock == -1) {
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fprintf(stderr, "打开socket错误\n");
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return -1;
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}
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sin.sin_family = AF_INET;
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if (INADDR_NONE == (sin.sin_addr.s_addr = inet_addr(server_ip))) {
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fprintf(stderr, "无效的远程IP地址\n");
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return -1;
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}
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int optval = 1;
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if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)) < 0)
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{
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perror("setsockopt");
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exit(1);
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}
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sin.sin_port = htons(22); /* SSH端口 */
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if (connect(sock, (struct sockaddr *)(&sin), sizeof(struct sockaddr_in)) != 0) {
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fprintf(stderr, "连接失败！\n");
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return -1;
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}
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/* 创建会话实例 */
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session = libssh2_session_init();
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if (!session) {
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fprintf(stderr, "无法初始化SSH会话！\n");
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return -1;
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}
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/* 启动会话。这将交换欢迎消息，交换密钥，并设置加密、压缩和MAC层 */
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rc = libssh2_session_handshake(session, sock);
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if (rc) {
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fprintf(stderr, "启动SSH会话时出错: %d\n", rc);
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return -1;
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}
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/* 此时我们还没有进行身份验证。首先要做的是检查主机密钥的指纹是否与我们的已知主机匹配。你的应用程序可以硬编码它，可以去文件中读取，可以向用户展示，这取决于你。 */
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fingerprint = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1);
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fprintf(stdout, "指纹: ");
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for (i = 0; i < 20; i++)
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fprintf(stdout, "%02X ", (unsigned char)fingerprint[i]);
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fprintf(stdout, "\n");
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/* 检查可用的身份验证方法 */
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userauthlist = libssh2_userauth_list(session, username, strlen(username));
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fprintf(stderr, "身份验证方法: %s\n", userauthlist);
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if (strstr(userauthlist, "password"))
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auth |= AUTH_PASSWORD;
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if (strstr(userauthlist, "publickey"))
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auth |= AUTH_PUBLICKEY;
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/* 检查选项 */
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if (argc > 8) {
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if ((auth & AUTH_PASSWORD) && !strcasecmp(argv[8], "-p"))
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auth = AUTH_PASSWORD;
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if ((auth & AUTH_PUBLICKEY) && !strcasecmp(argv[8], "-k"))
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auth = AUTH_PUBLICKEY;
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}
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if (auth & AUTH_PASSWORD) {
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if (libssh2_userauth_password(session, username, password)) {
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fprintf(stderr, "密码认证失败。\n");
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goto shutdown;
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}
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} else if (auth & AUTH_PUBLICKEY) {
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if (libssh2_userauth_publickey_fromfile(session, username, keyfile1, keyfile2, password)) {
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fprintf(stderr, "公钥认证失败！\n");
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goto shutdown;
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}
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fprintf(stderr, "公钥认证成功。\n");
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} else {
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fprintf(stderr, "未找到支持的认证方法！\n");
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goto shutdown;
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}
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fprintf(stdout, "请求服务器监听远程 %s:%d\n", remote_listenhost, remote_wantport);
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listener = libssh2_channel_forward_listen_ex(session, NULL, remote_wantport, &remote_listenport, 2);
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if (!listener) {
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fprintf(stderr, "无法启动tcpip-forward监听器！\n" "(请注意，这可能是服务器的问题！请查看服务器日志。）\n");
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goto shutdown;
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}
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fprintf(stdout, "服务器正在监听 %s:%d\n", remote_listenhost, remote_listenport);
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while (1) {
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fprintf(stdout, "等待远程连接\n");
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channel = libssh2_channel_forward_accept(listener);
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if (!channel) {
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fprintf(stderr, "libssh2_channel_forward_accept() 无法接受连接！\n" "(请注意，这可能是服务器的问题！请查看服务器日志。）\n");
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goto shutdown;
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}
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forward_tunnel(session, channel);
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libssh2_channel_free(channel);
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}
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shutdown:
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if (channel)
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libssh2_channel_free(channel);
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if (listener)
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libssh2_channel_forward_cancel(listener);
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libssh2_session_disconnect(session, "客户端正常断开连接");
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libssh2_session_free(session);
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close(sock);
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libssh2_exit();
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return 0;
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}
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