Ошибка соединения 595 no route to host

When you’re trying to connect to a service on Linux, “No route to host” is one of the last things you want to hear. It’s a broad message that means your computer can’t reach the target server, whether a local server daemon running on your system or a remote server that you can’t access for whatever reason. Here we show you how to fix the “no route to host” connection error in Linux.

Why Am I Getting the “No Route to Host” error?

There are many reasons why you could be getting that error. Networking in Linux is a somewhat complicated stack that’s pretty intricate, and as a result, it’s tough to determine exactly where the issue is.

Host Is Offline/Service Isn’t Running

It may seem painfully obvious, but you should first check that the server that you’re trying to connect to is even online. It might have been taken down for maintenance or be experiencing issues.

The service itself might not have been started. If it’s your server, you can check to see if the service has been started and is running properly. To do that with Systemd, run the following command.

sudo systemctl status SERVICENAME

Wrong Port

You may be trying to connect on the incorrect port. Many system administrators choose to run commonly targeted services like SSH on different ports to help thwart would-be attackers.

If the server isn’t your own, check the available documentation or contact their support services.

For your own server, you can try using NMAP to figure out where you started your service.

sudo nmap -sS your.server.ip

If you think you used a really obscure port, you can use the -p- flag to scan them all. It will take a while though.

Iptables Is Blocking the Connection

You may have accidentally configured iptables to block connections on that port. You would receive the same message whether you configured iptables on the server or your desktop, so it’s worth checking both. To see your iptables rules, run the following command.

Your DNS Is Improperly Configured

If all else fails, you should try to ping the IP address that you’re looking to connect to. It could be that your computer isn’t connecting to a DNS server properly.

If the ping works but connecting a domain name doesn’t, you’re looking at a DNS issue.

Systemd users can run systemd-resolve --status to check the DNS servers that your system is using. It’s broken down by interface, so make sure to check the one that you’re actually trying to connect through.

In most cases your computer will discover the relevant DNS information over DHCP. If you’re using a static IP or something on your network is configured differently, you may have to set your DNS manually.

Open “/etc/systemd/resolved.conf.” In that file, uncomment the DNS line and add either the IP of your router or another known DNS server. The default fallback DNS for Systemd is Google’s DNS servers listed under FallbackDNS.

If you’re using OpenRC or another Systemd alternative, you can find your DNS information in “/etc/resolv.conf.”

If there’s nothing there, enter the IP address of your router or any other known DNS server that you’d prefer to use.

After, either restart networking or your entire computer.

The GUI Way

If you’re using a graphical desktop with Network Manager, you can edit your connection information that way. Open the applet or go through your system settings. Select your connection and find the “IPv4” tab. Switch the connection to “Manual” and manually enter in the IP address of your computer and the IP of your router as the gateway. Then, in the DNS field below, enter your router’s IP or the IP of another DNS server.

Incorrect Network or Host Configuration

There are several other configuration options that may be incorrect. Any of them would make it impossible for your computer to connect to the server.

First, make sure that your computer’s network configuration is correct. Double-check the configuration files themselves and, of course, see if you can connect to the Internet another way.

If you’re using a specific hostname to connect or you’ve set up specific hosts on either the server or the client, you need to make sure both machines can connect to each other. Check the configurations of “/etc/hosts,” “/etc/hosts.allow,” and “/etc/hosts.deny.”

Finally, check your server configuration. Something may be improperly configured on the server, preventing clients from connecting properly.

Hopefully, using these tips has allowed you to fix whatever issues were happening that caused the “No Route to Host” error. Meanwhile, you can learn how to control your Wi-Fi network in Linux or check if your firewall is blocking any incoming and outgoing connection.

Linux is more often than not a hassle-free operating system to use. However, no OS on the planet is immune to networking issues, and the same stands true for Linux.

In this article, we’re looking at the “no route to host” error in Linux, its causes and how you can fix the problem.

What causes the ‘no route to host’ issue?

The error is primarily triggered when the network, server or host you’re trying to connect to you is not responding. It could indicate an inactive internet connection, incorrectly set up router profiles or any number of settings that can restrict your access to the particular server you’re trying to reach.

Also read: How to change file permissions recursively using Chmod in Linux?

How to fix the ‘no route to host’ issue?

Here are six solutions to try out and fix the no route to host issue.

Check your internet connection

Minecraft requires an active internet connection to work. If you have an unstable internet connection, chances are you’re going to miss out on notifications. Suppose you’re on WiFi check to see if you’ve got internet access and strong signals. If you’re on mobile data, check to see if data is enabled and that you’ve got good network coverage.

Incorrect network or host configuration files

Linux uses a bunch of configuration files to define several rules, which it then uses to connect to either the internet or a dedicated host over the internet or even your local network. Check to see if these files are in order and allow outgoing connections. Be sure to check the following three files at least:

/etc /hosts
/etc /hosts.allow
/etc /hosts.deny

Check your services

The most obvious thing can be whether the service you’re trying to connect to you is running or not. If you’re trying to connect to an external server, check its status to see if it’s running or not.

If you’re operating a server yourself, use the systemctl command to see if the service is running. 

sudo systemctl status [service name]

Also read: How to rename a directory in Linux?

Check the port

If the service is online, the next point of failure is most likely the port you’re connecting to. Most services change their default port as a security measure to avoid attackers from snooping in and causing damage. Check to see if you’re using the right port number.

If you’re using your server, try using NMAP to determine which port your service is running using the following command.

sudo nmap -sS [your server's IP]

Check IPTables

Another possible reason for the error could be IPTables blocking connections on the port the service is trying to communicate through. Check to see if the service is allowed to get through IPTables.

sudo iptables -S

DNS issues

If you can ping your server’s IP address but can’t resolve the domain name, you’re most likely facing a DNS issue. In most cases, your PC will fetch DNS information automatically using DHCP, but things can be different if you’re using static IP assignments. 

Here’s how you can set up your DNS manually.

Step 1: Navigate to the following directory and open the resolved.conf file.

/etc/systemd/

Step 2: Uncomment the DNS= line and add your router’s default IP.

If you’re using OpenRC or any other systemd alternative, your DNS files will be in /etc/resolve.conf. Once you’ve updated the rules, try restarting your router and PC. 

Also read: How to access command line history on Linux?

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»

Server code

#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

#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 refusedr");
                                                    break;
                                                case ENETUNREACH:
                                                    printf("*** No known router");
                                                    break;
                                                case EINTR:
                                                    printf("*** Connection timed outr");
                                                    break;
                                                default:
                                                    printf("ERROR: cannot connect to AX.25 callsignr");
                                                    break;
                                            }

                                            close(ax25_socket);
                                    }
                        printf("Connected!!r");
                        int n = write(ax25_socket,"Message!!!!",18);
                                if(n = -1)
                                    {
                                            perror("write--");
                                    }


                return 0;
}