C SSH远程执行命令

我正在尝试通过ssh连接到远程服务器并执行一个简单的命令。使用libssh库和以下代码

ssh_key pKey;
ssh_session session;
ssh_channel channel;
int rc = ssh_pki_import_privkey_file(PC_PRIVATE_KEY_FILE, NULL, NULL, NULL, &pKey);
char buffer[1024];
unsigned int nbytes;

printf("Session...\n");
session = ssh_new();
if (session == NULL) exit(-1);

ssh_options_set(session, SSH_OPTIONS_HOST, PC_HOST);
ssh_options_set(session, SSH_OPTIONS_USER, PC_USER);
ssh_options_set(session, SSH_OPTIONS_PORT, &PC_PORT);
ssh_options_set(session, SSH_OPTIONS_LOG_VERBOSITY, &PC_VERBOSITY);

printf("Connecting...\n");
rc = ssh_connect(session);
if (rc != SSH_OK) error(session);

printf("Channel...\n");
channel = ssh_channel_new(session);
if (channel == NULL) exit(-1);

printf("Opening...\n");
rc = ssh_channel_open_session(channel);
if (rc != SSH_OK) error(session);

printf("Executing remote command...\n");
rc = ssh_channel_request_exec(channel, "ls -l");
if (rc != SSH_OK) error(session);

printf("Received:\n");
nbytes = ssh_channel_read(channel, buffer, sizeof(buffer), 0);
while (nbytes > 0) {
    fwrite(buffer, 1, nbytes, stdout);
    nbytes = ssh_channel_read(channel, buffer, sizeof(buffer), 0);
}

ssh connect工作成功，但当它到达创建通道并执行命令的代码部分时，我会收到以下消息：

channel_open:  Creating a channel 43 with 64000 window and 32768 max packet
packet_send2:  packet: wrote [len=44,padding=19,comp=24,payload=24]
channel_open:  Sent a SSH_MSG_CHANNEL_OPEN type session for channel 43
ssh_socket_unbuffered_write:  Enabling POLLOUT for socket
ssh_packet_socket_callback:  packet: read type 3 [len=12,padding=6,comp=5,payload=5]
ssh_packet_process:  Dispatching handler for packet type 3
ssh_packet_unimplemented:  Received SSH_MSG_UNIMPLEMENTED (sequence number 3)

我做了一些研究，发现了一个类似于我现在讨论的问题，但被问题的首要答案弄糊涂了。还有，a，但没有解决我的问题的方法

我不知道如何解决我的问题。任何帮助都将不胜感激