In this tutorial you will learn:
- How to test internet connection
- How to test DNS resolution
- How to test Local Area network
- How to check your DNS resolution
Software Requirements and Conventions Used
|Category||Requirements, Conventions or Software Version Used|
|System||Installed or upgraded Ubuntu 20.04 Focal Fossa|
|Other||Privileged access to your Linux system as root or via the |
|Conventions|| # - requires given linux commands to be executed with root privileges either directly as a root user or by use of |
How to test Internet connection on Linux step by step instructionsLet's take a top-down approach to test and troubleshoot your Internet connection. Each of the steps below might provide you with hints on what the the problem with your internet connection might be and how to fix it.
- The first and the most obvious way on how to test your internet connection is to open up any Internet browser at your disposal and browse any live website. Fro example, navigate your browser to
In case you do not have graphical user interface available, use one of the many command line tools to connect to any website. For example try to use
curlcommand from your terminal:
$ curl -I https://linuxconfig.org HTTP/1.1 200 OK
200 OKwhen using the
curlcommand you might be happy to know that your Internet connection test was successful and you are connected to the Internet. If you still have issues to connect to any other desired Internet services then the issue might be related to firewall on your operating system, router and internet service provider.
- In case the first step did not resolve your issue, then it is time to check your internet connection on a lower level. To do so execute the following
pingcommand which will send network packets to an external server using its IP address. In this case let's try to ping Google's DNS server :
$ ping -c 2 18.104.22.168 PING 22.214.171.124 (126.96.36.199) 56(84) bytes of data. 64 bytes from 188.8.131.52: icmp_seq=1 ttl=54 time=10.4 ms 64 bytes from 184.108.40.206: icmp_seq=2 ttl=54 time=10.2 ms --- 220.127.116.11 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 1006ms rtt min/avg/max/mdev = 10.157/10.291/10.425/0.134 msThe above command should result in
0% packet loss.
- In case you are unable to ping the above IP address as shown in the previous step then you are either disconnected from the internet or your gateway settings of your network interface are incorrect.
Therefore, first retrieve your gateway IP address and try to see if you can reach it by using the
pingcommand. For example, first use the
ipcommand to to obtain your default gateway IP address:
$ ip r default via 192.168.1.1 dev enp0s3 proto dhcp metric 100Next, try to
pingthis IP address:
$ ping -c 1 192.168.1.1 PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. 64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=2.77 ms --- 192.168.1.1 ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 2.765/2.765/2.765/0.000 ms
- Next, step is to check your DNS server network configuration settings:
$ systemd-resolve --status | grep Current Current Scopes: DNS Current DNS Server: 192.168.1.1Our system is set to use DNS server host with an IP address
192.168.1.1. Make sure that you can reach your DNS server. Again, the
pingis a handy tool also here:
$ ping -c 2 192.168.1.1 PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. 64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.535 ms 64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=0.570 ms --- 192.168.1.1 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 1016ms rtt min/avg/max/mdev = 0.535/0.552/0.570/0.017 msOnce again, the output of the above command should result in
0% packet loss.
In case you cannot reach your DNS it could mean that it either, does not respond to ping's ICPM packages, it is behind the firewall or the server is down. In which case update your
/etc/resolv.confwith an alternative DNS server.
- Test you DNS server by attempting to resolve DNS name eg.
$ dig @192.168.1.1 linuxconfig.org ; <<>> DiG 9.16.1-Ubuntu <<>> @192.168.1.1 linuxconfig.org ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10032 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;linuxconfig.org. IN A ;; ANSWER SECTION: linuxconfig.org. 187 IN A 18.104.22.168 linuxconfig.org. 187 IN A 22.214.171.124 ;; Query time: 4 msec ;; SERVER: 192.168.1.1#53(192.168.1.1) ;; WHEN: Thu May 07 11:01:41 AEST 2020 ;; MSG SIZE rcvd: 76
- Confirm system-wide settings by trying to resolve DNS host name. Example:
$ resolvectl query linuxconfig.org linuxconfig.org: 126.96.36.199 -- link: enp0s3 188.8.131.52 -- link: enp0s3 -- Information acquired via protocol DNS in 2.7ms. -- Data is authenticated: no