Linux 如何一直实时查看TCP连接的情况

您可以使用命令行工具`tcpdump`和`ss`来实时查看TCP连接的情况。

`tcpdump`是一款网络抓包工具，可以捕获网络数据包，并将其输出到终端。您可以使用以下命令来实时查看TCP连接的情况：

sudo tcpdump -i eth0 tcp

其中，`-i`参数指定要监听的网络接口，`tcp`参数表示只捕获TCP数据包。

另外，您也可以使用`ss`命令来查看TCP连接的状态。以下命令可以实时显示所有TCP连接及其状态：

watch -n1 'ss -tan'

其中，`watch`命令可以定时执行一个命令，并将其输出显示在终端上，`-n1`参数表示每一秒执行一次命令。`ss -tan`命令用于显示所有TCP连接及其状态。

相关问题

linux建立服务端能一直接收客户端连接接受信息 c语言代码

可以使用socket编程实现，以下是一个简单的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>

#define PORT 8888
#define MAX_CLIENTS 10

int main() {
    int server_fd, new_socket, valread;
    struct sockaddr_in address;
    int opt = 1;
    int addrlen = sizeof(address);
    char buffer[1024] = {0};
    char *hello = "Hello from server";

    // 创建socket
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    // 设置socket选项
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, sizeof(opt))) {
        perror("setsockopt failed");
        exit(EXIT_FAILURE);
    }

    // 绑定地址和端口
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(PORT);

    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }

    // 监听连接
    if (listen(server_fd, MAX_CLIENTS) < 0) {
        perror("listen failed");
        exit(EXIT_FAILURE);
    }

    printf("Server listening on port %d\n", PORT);

    // 接受连接并处理请求
    while (1) {
        if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {
            perror("accept failed");
            exit(EXIT_FAILURE);
        }

        printf("New client connected: %s:%d\n", inet_ntoa(address.sin_addr), ntohs(address.sin_port));

        // 接收客户端发送的数据
        valread = read(new_socket, buffer, 1024);
        printf("Received message from client: %s\n", buffer);

        // 发送响应给客户端
        send(new_socket, hello, strlen(hello), 0);
        printf("Hello message sent to client\n");

        // 关闭连接
        close(new_socket);
    }

    return 0;
}

这个代码可以建立一个简单的TCP服务端，可以接收客户端的连接并接收数据，然后发送响应给客户端。你可以根据自己的需求修改代码。

qt做客户端 linux服务器 利用TCP实现登陆注册

下面是一个简单的示例代码，演示如何利用Qt实现TCP通信，实现客户端登陆注册功能：

客户端代码：

#include <QtNetwork>
#include <QDataStream>
#include <QDebug>

class Client : public QObject
{
    Q_OBJECT

public:
    Client(QObject *parent = nullptr)
        : QObject(parent)
    {
        m_socket = new QTcpSocket(this);

        connect(m_socket, &QTcpSocket::connected, this, &Client::onConnected);
        connect(m_socket, &QTcpSocket::disconnected, this, &Client::onDisconnected);
        connect(m_socket, &QTcpSocket::readyRead, this, &Client::onReadyRead);
        connect(m_socket, QOverload<QAbstractSocket::SocketError>::of(&QAbstractSocket::error), this, &Client::onError);

        m_socket->connectToHost("127.0.0.1", 1234);
    }

    void login(const QString &username, const QString &password)
    {
        QByteArray data;
        QDataStream stream(&data, QIODevice::WriteOnly);
        stream << qint8(1) << username << password;
        m_socket->write(data);
    }

    void registerUser(const QString &username, const QString &password)
    {
        QByteArray data;
        QDataStream stream(&data, QIODevice::WriteOnly);
        stream << qint8(2) << username << password;
        m_socket->write(data);
    }

private slots:
    void onConnected()
    {
        qDebug() << "Connected to server.";
    }

    void onDisconnected()
    {
        qDebug() << "Disconnected from server.";
    }

    void onReadyRead()
    {
        QDataStream stream(m_socket);
        while (!stream.atEnd()) {
            qint8 cmd;
            stream >> cmd;

            switch (cmd) {
            case 1: { // login response
                bool success;
                stream >> success;
                if (success) {
                    qDebug() << "Login successful.";
                } else {
                    qDebug() << "Login failed.";
                }
                break;
            }
            case 2: { // register response
                bool success;
                stream >> success;
                if (success) {
                    qDebug() << "Registration successful.";
                } else {
                    qDebug() << "Registration failed.";
                }
                break;
            }
            default:
                qDebug() << "Unknown command:" << cmd;
                break;
            }
        }
    }

    void onError(QAbstractSocket::SocketError error)
    {
        qDebug() << "Socket error:" << error << m_socket->errorString();
    }

private:
    QTcpSocket *m_socket;
};

服务器端代码：

#include <QtNetwork>
#include <QDataStream>
#include <QDebug>

class Server : public QObject
{
    Q_OBJECT

public:
    Server(QObject *parent = nullptr)
        : QObject(parent)
    {
        m_server = new QTcpServer(this);

        connect(m_server, &QTcpServer::newConnection, this, &Server::onNewConnection);

        if (!m_server->listen(QHostAddress::Any, 1234)) {
            qDebug() << "Failed to start server:" << m_server->errorString();
            return;
        }

        qDebug() << "Listening on port 1234...";
    }

private slots:
    void onNewConnection()
    {
        QTcpSocket *socket = m_server->nextPendingConnection();
        qDebug() << "New connection from" << socket->peerAddress().toString() << socket->peerPort();

        connect(socket, &QTcpSocket::disconnected, socket, &QTcpSocket::deleteLater);
        connect(socket, &QTcpSocket::readyRead, this, &Server::onReadyRead);
        connect(socket, QOverload<QAbstractSocket::SocketError>::of(&QAbstractSocket::error), this, &Server::onError);

        m_clients.append(socket);
    }

    void onReadyRead()
    {
        QTcpSocket *socket = qobject_cast<QTcpSocket *>(sender());
        Q_ASSERT(socket);

        QDataStream stream(socket);
        while (!stream.atEnd()) {
            qint8 cmd;
            stream >> cmd;

            switch (cmd) {
            case 1: { // login request
                QString username, password;
                stream >> username >> password;
                bool success = checkLogin(username, password);
                QByteArray data;
                QDataStream response(&data, QIODevice::WriteOnly);
                response << qint8(1) << success;
                socket->write(data);
                break;
            }
            case 2: { // register request
                QString username, password;
                stream >> username >> password;
                bool success = registerUser(username, password);
                QByteArray data;
                QDataStream response(&data, QIODevice::WriteOnly);
                response << qint8(2) << success;
                socket->write(data);
                break;
            }
            default:
                qDebug() << "Unknown command:" << cmd;
                break;
            }
        }
    }

    void onError(QAbstractSocket::SocketError error)
    {
        QTcpSocket *socket = qobject_cast<QTcpSocket *>(sender());
        Q_ASSERT(socket);

        qDebug() << "Socket error:" << error << socket->errorString();

        m_clients.removeOne(socket);
        socket->deleteLater();
    }

private:
    bool checkLogin(const QString &username, const QString &password)
    {
        // TODO: check username and password against database
        return true;
    }

    bool registerUser(const QString &username, const QString &password)
    {
        // TODO: add username and password to database
        return true;
    }

    QTcpServer *m_server;
    QList<QTcpSocket *> m_clients;
};

在这个示例中，客户端与服务器端都是单线程的，因此接收到数据时会一直阻塞，直到数据全部接收完成。如果需要支持并发处理，可以将每个连接分配给一个新线程处理。另外，此示例中的用户名和密码是明文传输的，需要添加加密传输的支持来保护用户隐私。