无法在VPN中连接到本地服务器

Question

我在多个iOS、MacOS中尝试过以下代码。

这是服务器代码

void *run_server(void *thread_id) {
int server_fd, new_socket;
struct sockaddr_in server, client;
int opt = 1;
int addrlen = sizeof(server);

// Creating socket file descriptor
if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
perror("socket");
return NULL;
}
// Forcefully attaching socket to the port
if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt))) {
perror("setsockopt");
return NULL;
}
server.sin_family = AF_INET;
server.sin_addr.s_addr = ip("10.10.10.20"); // bind IP
server.sin_port = htons(27042);

// Forcefully attaching socket to the port
if (bind(server_fd, (struct sockaddr *)&server, sizeof(server)) < 0) {
perror("bind");
return NULL;
}
if (listen(server_fd, 3) < 0) {
perror("listen");
return NULL;
}
printf("Server is running with %u:%dn", server.sin_addr.s_addr, htons(server.sin_port));
while (1) {
if ((new_socket = accept(server_fd, (struct sockaddr *)&client, (socklen_t*)&addrlen))<0) {
perror("accept");
return NULL;
}

printf("Client connected with %u:%dn", client.sin_addr.s_addr, client.sin_port);
}
}

这是客户端代码

void scan(unsigned int ip, int port) {
int sock = 0;
struct sockaddr_in serv_addr;
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
printf("nSocket creation errorn");
return;
}
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(port);
serv_addr.sin_addr.s_addr = ip;
printf("IP %u, port %dn", ip, port);
int connected = connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr));
if (connected != 0) {
char errorMsg[256];
strerror_r(errno, errorMsg, 256);
printf("Error %sn", errorMsg);
}
if (connected < 0) {
close(sock);
return;
}
}
void *run_scan(void *thread_id) {
while (1) {
scan(ip("10.10.10.20"), 27042);
usleep(1000000);
}
return NULL;
}

以及的主要功能

int main(int argc, const char * argv[]) {
pthread_t thread1;
if (pthread_create(&thread1, NULL, run_server, (void *)1)) {
printf("Can't create thread run_server");
}
pthread_t thread2;
if (pthread_create(&thread2, NULL, run_scan, (void *)2)) {
printf("Can't create thread run_scan");
}
while (1) sleep(1);
return 0;
}

问题描述：此代码与本地IP(DHCP分配的IP(一起正常工作。然而，当我连接到VPN并将服务器IP绑定到PPP网络接口IP时，该IP为10.10.10.20(如上示例代码所示(。我无法打开与该IP的连接。错误是"；连接超时"；。注意，其他主机仍然可以连接到IP为10.10.10.20的服务器。

如果有任何关于这种情况的知识分享，我们将不胜感激。

Answer 1

找到了答案，基本上这是Linux内核施加的限制。

更多信息：https://www.softether.org/4-docs/1-manual/B._Troubleshooting_and_Supplemental/11.1_Troubleshooting