回环地址是什么（lo回环地址）

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 <p id="2UN7P9AQ"><br/>在计算机网络中，环回（Loopback）IP地址是一种特殊的IP地址，通常被用于测试网络软件、网络设备和网络协议，而无需实际的数据包通过物理网络。IPv4中最常见的环回地址是<strong>127.0.0.1</strong>，而在IPv6中则是<strong>::1</strong>。环回地址为可以简洁的验证网络配置和调试网络应用程序。</p><p class="f_center"><img src="https://nimg.ws.126.net/?url=http%3A%2F%2Fdingyue.ws.126.net%2F2024%2F0816%2Fd323a852j00siawet00aad000v900jdp.jpg&thumbnail=660x&quality=80&type=jpg"/><br/>环回IP地址：原理、应用<br/></p><p id="2UN7P9AT"><strong>原理</strong></p><p id="2UN7P9AU">环回IP地址主要用于自我通信。当一个计算机系统通过环回地址发送数据包时，数据包并不经过网络传输，而是被网络协议栈直接返回给发送应用程序。这种机制使得开发人员能够在不影响网络的情况下测试和调试网络应用。</p><p id="2UN7P9AV">在TCP/IP协议中，任何指向127.0.0.0/8的地址都被视为环回地址，但通常只使用127.0.0.1。使用环回地址时，数据包只在主机内部传输，不会在任何物理网络中出现。这不仅简化了测试过程，还提高了网络测试的安全性。</p><p id="2UN7P9B0"><strong>应用</strong></p><p id="2UN7P9B1">网络应用测试：开发人员可以使用环回地址在同一台机器上测试客户端和服务器的网络通信。这使得在应用发布之前，对其进行广泛的功能性测试成为可能。</p><p id="2UN7P9B2">网络配置验证：系统管理员通过环回地址验证网络服务的配置，如数据库服务等，而无需实际的网络连接。</p><p id="2UN7P9B3">开发环境的隔离：在开发环境中，开发者可以使用环回地址将测试流量与实际网络流量隔离，防止开发中的应用对网络产生影响。</p><p id="2UN7P9B4">https://www.ipdatacloud.com/?utm-source=LMN&amp;utm-keyword=?2091</p><p id="2UN7P9B5">网络故障排除：通过环回地址，网络工程师可以验证本地网络堆栈的功能性，从而区分本地和远程网络故障。</p><p id="2UN7P9B6"><strong>编程示例</strong></p><p id="2UN7P9B7">Python示例</p><p id="2UN7P9B8">“<strong># server.py</strong></p><p id="2UN7P9B9"><strong>import socket</strong></p><p id="2UN7P9BA"><strong>HOST = '127.0.0.1' #环回地址</strong></p><p id="2UN7P9BB"><strong>PORT = 65432 #任意非保留端口</strong></p><p id="2UN7P9BC"><strong>with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:</strong></p><p id="2UN7P9BD"><strong>s.bind((HOST, PORT))</strong></p><p id="2UN7P9BE"><strong>s.listen()</strong></p><p id="2UN7P9BF"><strong>print('Server listening on', (HOST, PORT))</strong></p><p id="2UN7P9BG"><strong>conn, addr = s.accept()</strong></p><p id="2UN7P9BH"><strong>with conn:</strong></p><p id="2UN7P9BI"><strong>print('Connected by', addr)</strong></p><p id="2UN7P9BJ"><strong>while True:</strong></p><p id="2UN7P9BK"><strong>data = conn.recv(1024)</strong></p><p id="2UN7P9BL"><strong>if not data:</strong></p><p id="2UN7P9BM"><strong>break</strong></p><p id="2UN7P9BN"><strong>conn.sendall(data)</strong></p><p id="2UN7P9BO"><strong># client.py</strong></p><p id="2UN7P9BP"><strong>import socket</strong></p><p id="2UN7P9BQ"><strong>HOST = '127.0.0.1' #环回地址</strong></p><p id="2UN7P9BR"><strong>PORT = 65432 #与服务器相同的端口</strong></p><p id="2UN7P9BS"><strong>with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:</strong></p><p id="2UN7P9BT"><strong>s.connect((HOST, PORT))</strong></p><p id="2UN7P9BU"><strong>s.sendall(b'Hello, world')</strong></p><p id="2UN7P9BV"><strong>data = s.recv(1024)</strong></p><p id="2UN7P9C0"><strong>print('Received', repr(data))</strong>”</p><p id="2UN7P9C1">C示例</p><p id="2UN7P9C2">“<strong>// server.c</strong></p><p id="2UN7P9C3"><strong>#include</strong></p><p id="2UN7P9C4"><strong>#include</strong></p><p id="2UN7P9C5"><strong>#include</strong></p><p id="2UN7P9C6"><strong>#include</strong></p><p id="2UN7P9C7"><strong>#include</strong></p><p id="2UN7P9C8"><strong>#include</strong></p><p id="2UN7P9C9"><strong>#define PORT 65432</strong></p><p id="2UN7P9CA"><strong>#define BUFFER_SIZE 1024</strong></p><p id="2UN7P9CB"><strong>int main() {</strong></p><p id="2UN7P9CC"><strong>int server_fd, new_socket;</strong></p><p id="2UN7P9CD"><strong>struct sockaddr_in address;</strong></p><p id="2UN7P9CE"><strong>char buffer[BUFFER_SIZE] = {0};</strong></p><p id="2UN7P9CF"><strong>int opt = 1;</strong></p><p id="2UN7P9CG"><strong>int addrlen = sizeof(address);</strong></p><p id="2UN7P9CH"><strong>//创建socket文件描述符</strong></p><p id="2UN7P9CI"><strong>if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {</strong></p><p id="2UN7P9CJ"><strong>perror("socket failed");</strong></p><p id="2UN7P9CK"><strong>return -1; }</strong></p><p id="2UN7P9CL"><strong>//将socket绑定到地址和端口</strong></p><p id="2UN7P9CM"><strong>address.sin_family = AF_INET;</strong></p><p id="2UN7P9CN"><strong>address.sin_addr.s_addr = INADDR_ANY;</strong></p><p id="2UN7P9CO"><strong>address.sin_port = htons(PORT);</strong></p><p id="2UN7P9CP"><strong>if (bind(server_fd, (struct sockaddr *)&amp;address, sizeof(address)) &lt; 0) {</strong></p><p id="2UN7P9CQ"><strong>perror("bind failed");</strong></p><p id="2UN7P9CR"><strong>return -1; }</strong></p><p id="2UN7P9CS"><strong>//监听连接</strong></p><p id="2UN7P9CT"><strong>if (listen(server_fd, 3) &lt; 0) {</strong></p><p id="2UN7P9CU"><strong>perror("listen");</strong></p><p id="2UN7P9CV"><strong>return -1; }</strong></p><p id="2UN7P9D0"><strong>printf("Server listening on port %d

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”, PORT);

//接受连接

if ((new_socket = accept(server_fd, (struct sockaddr )&address, (socklen_t)&addrlen)) < 0) {

perror(“accept”);

return -1; }

//读取客户端发送的数据并回传

read(new_socket, buffer, BUFFER_SIZE);

printf(“Received: %s “, buffer);

send(new_socket, buffer, strlen(buffer), 0);

close(new_socket);

close(server_fd);

return 0;}

// client.c

#include

#define PORT 65432

#define BUFFER_SIZE 1024

int main() {

int sock = 0;

struct sockaddr_in serv_addr;

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char *hello = “Hello from client”;

char buffer[BUFFER_SIZE] = {0};

//创建socket文件描述符

if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {

printf(” Socket creation error “);

return -1; }

//设置服务器地址

serv_addr.sin_family = AF_INET;

serv_addr.sin_port = htons(PORT);

//转换环回地址

if (inet_pton(AF_INET, “127.0.0.1”, &serv_addr.sin_addr) <= 0) {

printf(” Invalid address/ Address not supported “);

return -1; }

//连接到服务器

if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {

printf(” Connection Failed “);

return -1;}

//发送数据并接收回传

send(sock, hello, strlen(hello), 0);

read(sock, buffer, BUFFER_SIZE);

printf(“Received: %s “, buffer);

close(sock);

return 0;}”

安全性

由于环回地址不在网络上进行传输，所以是非常安全的。所以被用来测试应用程序或网络服务，避免意外的数据泄漏或安全问题。但仍需注意确保在实际部署环境中进行适当的网络和安全配置，以防止潜在的攻击。

回环地址是什么（lo回环地址）

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