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Introduction
Troubleshooting is the process in which we analyse and solve a series of problems in the system. Similarly, network troubleshooting is the act in which we discover the issue and improve it with regard to its security, connectivity, and many more. It is the duty of sysadmins to perform this task regularly. Thus, it becomes important to know the correct tool to achieve the results in a faster and more accurate way.
In this blog, we will look at various network troubleshooting tools in Linux in detail. So without any further wait, let’s start learning!
About Linux
Linux was released by Linus Torvalds in the year 1991. It is an open-source operating system with a wide global user base. Linux is an operating system just like Windows, Mac, and iOS. It was created for personal computers but later used in mainframe computers, servers, etc. It is also used in routers, televisions, video recorders, smartwatches, etc.
Now, let us look at some of the most used network troubleshooting tools in Linux.
ip Command
The IP stands for Internet Protocol. It is a command in Linux which is available in net-tools. This command is used to show and manipulate devices, routing, and tunnels. It is an all-in-one command which can manipulate network objects on your Linux system.
Syntax
ip < object > [command]
Some of the most common objects used are:
link: It displays link layer information.
address: It shows all IP addresses of all network devices.
route: It is used to handle routing table entries.
Examples
Let’s now look at some examples around ip command.
Show all the IP addresses
In order to show all the IP addresses of all the associated devices, we can use the below syntax:
ip address
This will show the IP address of the interfaces on the system.
Show the IP address of a particular interface
To show the IP address of a particular interface, you can use the below syntax:
ip address show interface_name
The link command will display the link layer information. It will fetch the information of networking devices which has a driver loaded.
Show the link status of networking devices
The command to show the link status of networking devices is:
ip link
Show the statistics of network interfaces
To show the statistics of network interfaces, you can use the below command:
ip -s link
Get information about a particular interface
You can get information about a particular interface by just adding a show command followed by the interface name.
Display the routing table of your network
The route command will display the routing table of your network.
ip route
The first entry is the default route of the network.
nslookup Command
The nslookup stands for Name Server Lookup. It is a command that fetches information from the DNS server. It is used to troubleshoot DNS-related issues.
To install it, use the below command:
Syntax
nslookup <options>
Examples
Display the IP address of the domain name
The nslookup followed by the domain name will display the IP address of the domain name. It will query the domain name servers and fetch you the result.
Reverse DNS lookup
The above command performed a basic DNS lookup. Similarly, we can do a reverse DNS lookup by passing the IP address as the argument.
View all the available DNS records
We can also view all the available DNS records using the following command:
nslookup -type=any <address>
nmcli Tool
The nmcli is a command-line tool that is used to control the network manager. It will allow you to view the device status, create, edit, and delete network connections, etc.
Syntax
nmcli <object> [command]
Examples
Check the device status
In order to check the device status, you can use the below command:
nmcli dev status
It will show the type and state of the connected device in columns.
View the active connections
To view the active connections on the device, use the below command:
nmcli connection
View a specific connection
To view a specific connection, you can use the following command:
nmcli connection show enp1s3
This will show the status of the specified interface.
Display help-related information
You can also display help-related information in case of any problem.
ping Command
The ping stands for Packet Internet Groper. It is a command which is used to check the network connectivity between the host and the server. It takes the URL as input and sends data packets to the specified address, and gets back the response from the server.
Syntax
ping <hostname>
Examples
Control the ping number
The above command will ping the host and send packets to it continuously. To control the pink number, you can use the -c option followed by the number of pings.
Here, the min, avg, and max are the minimum, average, and maximum time to get the response.
Change the default packet size
You can change the default packet size sent to the host using the -s option.
Change the default wait period
By default, the ping waits for 1 sec to send the consecutive packet. We can change this period using the -i option.
Completely stop the pinging
To completely stop the pinging after a specific duration, use the -w options.
Here, we wanted to ping 5 times, but it happened only 3 times because, after 3 seconds, the ping was stopped due to the -w option.
Frequently Asked Questions
What are network troubleshooting tools in Linux?
In Linux, the network troubleshooting tools are the set of command line utilities that helps to diagnose and resolve network issues.
Which command is used to check network connectivity in Linux?
The ping command in Linux is used to check the connectivity to a specific domain name or IP address.
Which command is used to check the DNS resolution in Linux?
The nslookup command is used to query the DNS server and verify the domain name for a correct IP address.
How to list all the available network connections in Linux?
You can use the command nmcli connection show to list all the available network connections on your Linux system.
Conclusion
This article discusses the network troubleshooting tools in Linux. We discussed various commands available in Linux for network troubleshooting in detail. We hope this blog has helped you enhance your knowledge of network troubleshooting tools in Linux. If you want to learn more, then check out our articles.
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