Linux 连接错误：“没有到主机的路由”
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connect Error: "No route to host"
提问by user2772956
i'm writing a server/client c program based on AX.25 protocol. The server creating the socket, binding Successfully and listening for coming connections. the client running in a different thread but fails on connect with " No route to host"
我正在编写一个基于 AX.25 协议的服务器/客户端 c 程序。服务器创建套接字，成功绑定并侦听即将到来的连接。客户端在不同的线程中运行但连接失败并显示“没有到主机的路由”
Server code
服务器代码
#include <sys/socket.h>
#include <netax25/ax25.h>
#include <netax25/axlib.h>
#include <netax25/axconfig.h>
#include <stdio.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <syslog.h>
#include <sys/types.h>
#include <linux/socket.h>
#include <stdlib.h>
#include <sys/un.h>
#include <string.h>
#include <errno.h>
int main(int argc,char **argv,char **envp) {
int ax25_socket = -1;
unsigned char buffer[512];
struct full_sockaddr_ax25 addr, axconnect ;
char *port ="3";// sm0 port number:3
char *call = "OH2BNS-8";// sm0 callsign
bzero((char *) &addr, sizeof(struct full_sockaddr_ax25));
addr.fsa_ax25.sax25_family = AF_AX25;
addr.fsa_ax25.sax25_ndigis = 1;
if (ax25_config_load_ports() == 0) {
printf( "Problem with axports file");
//return -1;
}
char* ax25port = (char*) ax25_config_get_addr(port);
ax25_aton_entry( call, addr.fsa_ax25.sax25_call.ax25_call);
ax25_aton_entry( ax25port, addr.fsa_digipeater[0].ax25_call);
ax25_socket = socket(AF_AX25, SOCK_SEQPACKET, 0);
if (ax25_socket < -1)
printf( "error in create socket");
if (bind(ax25_socket, (struct sockaddr *)&addr, sizeof(struct full_sockaddr_ax25)) < 0) {
perror("bind--");
return -1;
}
if(listen(ax25_socket,2) != 0)
{
printf("cannot listen on socket!\n");
close(ax25_socket);
return 0;
}
puts("listening");
//bzero((char *) &axconnect, sizeof(struct full_sockaddr_ax25));
int len =sizeof(struct full_sockaddr_ax25);
int temp_sock_desc = accept(ax25_socket, (struct sockaddr*)&axconnect, &len);
if (temp_sock_desc == -1)
{
printf("cannot accept client!\n");
close(ax25_socket);
return 0;
}
return 0;
}
Client code
客户端代码
#include <sys/socket.h>
#include <netax25/ax25.h>
#include <netax25/axlib.h>
#include <netax25/axconfig.h>
#include <stdio.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <syslog.h>
#include <sys/types.h>
#include <linux/socket.h>
#include <stdlib.h>
#include <sys/un.h>
#include <string.h>
#include <errno.h>
int main(int argc, char *argv[])
{
int ax25_socket = -1;
unsigned char buffer[512];
struct full_sockaddr_ax25 axconnect ;
char *port ="3";// sm0 port number:3
char *call ="OH2BNS-8";// sm0 callsign
bzero((char *) &axconnect, sizeof(struct full_sockaddr_ax25));
axconnect.fsa_ax25.sax25_family = AF_AX25;
axconnect.fsa_ax25.sax25_ndigis = 1;
if (ax25_config_load_ports() == 0) {
printf( "Problem with axports file");
//return -1;
}
char* ax25port = (char*) ax25_config_get_addr(port);
ax25_aton_entry( call, axconnect.fsa_ax25.sax25_call.ax25_call);
ax25_aton_entry( ax25port, axconnect.fsa_digipeater[0].ax25_call);
ax25_socket = socket(AF_AX25, SOCK_SEQPACKET, 0);
if (ax25_socket < -1)
printf( "error in create socket");
if (connect(ax25_socket, (struct sockaddr *)&axconnect, sizeof(struct full_sockaddr_ax25)) != 0) {
perror("--");
switch (errno) {
case ECONNREFUSED:
printf("*** Connection refused\r");
break;
case ENETUNREACH:
printf("*** No known route\r");
break;
case EINTR:
printf("*** Connection timed out\r");
break;
default:
printf("ERROR: cannot connect to AX.25 callsign\r");
break;
}
close(ax25_socket);
}
printf("Connected!!\r");
int n = write(ax25_socket,"Message!!!!",18);
if(n = -1)
{
perror("write--");
}
return 0;
}
回答by Manoj Pandey
Simply put, a " No route to host"" would mean that there is no route for the server IP address in the client's routing table. Are you able to ping the server's IP address? Most likely you should not be able to and ping should say that the server is not reachable. If so, then this error has nothing to do with your program, you are probably running into a connectivity issue.
简单地说，“没有到主机的路由”意味着在客户端的路由表中没有服务器 IP 地址的路由。你能 ping 通服务器的 IP 地址吗？很可能你不应该能 ping 通说服务器无法访问。如果是这样，那么这个错误与您的程序无关，您可能遇到了连接问题。
Can you find the entry for your server in the output of "route -n". If there is none, then you should check for a bigger prefix for the subnet of the server. If that also is not present, then you should confirm that you have a default route setup.
你能在“route -n”的输出中找到你的服务器的条目吗？如果没有，那么您应该检查服务器子网的更大前缀。如果这也不存在，那么您应该确认您有默认路由设置。
To further confirm, I would do the following two tests. First, what happens if you try to run the client/server on the same box? Second, what happens if you try to run the client/server on two boxes (present in the same subnet) and on the same LAN? If you do not see this issue and your application works just fine, then this should confirm that you are running into a connectivity issue.
为了进一步确认，我将进行以下两个测试。首先，如果您尝试在同一台机器上运行客户端/服务器会发生什么？其次，如果您尝试在两个机器（位于同一子网中）和同一 LAN 上运行客户端/服务器，会发生什么情况？如果您没有看到此问题并且您的应用程序运行良好，那么这应该确认您遇到了连接问题。
回答by Steven R. Loomis
I know this is an old question, but I would suspect a problem with ax25port- should be something like YOURCALL-0where YOURCALL matches the HWaddr of an existing ax25 port ( try /sbin/ifconfig | fgrep AX.25
我知道这是一个老问题，但我怀疑有问题ax25port- 应该类似于YOURCALL-0YOURCALL 匹配现有 ax25 端口的 HWaddr（尝试/sbin/ifconfig | fgrep AX.25
