Network monitoring and troubleshooting is an essential part of any Network administrator’s job and task list. There are lots of tools available in the market to troubleshoot a variety of different network conditions, outages, issues and connectivity problems.
In this tutorial, we will discuss some commonly used Network Troubleshooting Tools that will help you diagnose most networking issues.
Here is our list of the twelve best Linux network troubleshooting tools:
- ManageEngine OpManager (FREE TRIAL) A full-feature network monitoring and management system with a professional graphical user interface. OpManager can supervise the normal operations of your network and alert you when problems arise. Installs on Linux and Windows Server.
- Ping A very widely used command line utility that tests remote host availability and reports on roundtrip time, packet loss, and jitter.
- Ifconfig A command line system query that returns the current host’s IP addressing statuses.
- NetStat Displays both incoming and outgoing connections active on the current system.
- Dig A utility that enables you to test your current DNS server.
- NSLookup A DNS lookup and reverse lookup mechanism.
- Route View or alter entries in the local routing table.
- Host A DNS name lookup and reverse lookup tool.
- ARP Address Resolution Protocol implementation checker. Reads the mapping between IP addresses and MAC addresses.
- EthTool A command line tool that enables the Ethernet adapter settings to be viewed or edited.
- IWConfig View a wireless adapter configuration and edit it.
- Hostname View and change the host name of the current system.
Here’s the Best Free Linux Network Troubleshooting Tools & Utilities of 2021:
Before looking at simple commands to query network information from your network card or operating system, we’ll take a look at a full network monitoring package that will perform ongoing network performance supervision. ManageEngine OpManager will perform all of your network monitoring tasks on your behalf, freeing up your time for other tasks. This utility also includes an automated server status checker as well.
The systems underlying the functionality of OpManager are those commands that you are going to read about in the next sections of this guide. However, rather than sitting and constantly issuing commands to discover network data and check on performance, you can let the OpManager package do that. It will also collect and collate all results and display them in a pleasing graphical interface.
One of the network systems that isn’t covered in the following sections is the Simple Network Management Protocol (SNMP). This is a network data communication system that gathers status information from network devices and also enables the collection of traffic statistics and switch configuration and connection information.
The information that the SNMP standard can supply gives a network administrator just about all the information that needs to be discovered about network operations. OpManager sets thresholds of reasonable performance and then compares each status check feedback with those levels of expectation.
If a specific condition deteriorates, OpManager will raise an alert. The system console displays those alerts but can also forward them to you by SMS or email. That means that you don’t have to sit and watch network performance data all day. You will be able to get back to the dashboard to fix things in time to head off disaster should OpManager notice that standards are slipping.
OpManager also performs the same status checks with alerts on servers. It is able to communicate with all servers across a network – it doesn’t just monitor the server on which it is resident.
The OpManager software needs to be downloaded and hosted. It will run on a Linux server and you can also get a version that runs on Windows Server. ManageEngine offers a 30-day free trial of OpManager.
PING also known as a “Packet Internet Groper” is a most commonly used network diagnostic tool that can be used to provide a basic connectivity test between the source host and a destination host. It is commonly used in conjunction with Server Monitoring Tools to ensure uptime is present at all times for critical infrastructure!
PING uses an ICMP protocol to send an echo packet to a destination host and a mechanism to listen for a response from this host.
You can use ping command with hostname or IP address as shown below:
You can also use ping with -c option to exit after a specified number of request:
ifconfig is a command line tool that reports the IPv4 and IPv6 addresses, subnets, and default gateways for all network adapters on your system. You can also assign IP address, enable and disable network interface with this command.
You can list IP address of all the network interface connected to your system with the following command:
You can list IP address of specific interface with the following command:
You can assign an IP address to specific interface with the following command:
ifconfig wlan0 192.168.0.123 netmask 255.255.0.0
You can also disable and enable network interface with the following command:
To enable interface wlan0:
To disable interface wlan0
Netstat is a command line tool that can be used to displays active connections on your system both incoming an outgoing.
Netstat is very useful when verifying the status of a listening port on a system and see what remote systems are connected to a local host on a specific port.
You can see all the active connections on your system with the following command:
You can also see routing table information with the following command:
Dig also known as “domain information groper” is a command line tool that can be used to verify DNS resolution. You can troubleshoot DNS related query and see DNS related information like A Record, CNAME, MX Record with the help of Dig command.
You can look up the A records for the domain name google.com with the following command:
You can look up the MX record for the domain name google.com with the following command:
You can look up all the record for the domain name google.com with the following command:
nslookup is another command line tool to query and verify DNS name resolution. It can be used to obtain domain name or IP address of computers in the internet.
You can use nslookup with the domain name to display the “A Record” (IP Address) of the domain:
You can also do the reverse DNS look-up by providing the IP Address with nslookup command:
You can see NS records of domain google.com with the following command:
You can see MX records of domain google.com with the following command:
Route is a command line tool that can be used to show/manipulate the IP routing table. You can also setup static routes to specific host or networks via an interface.
You can use route command without any argument to see the details of the kernel routing table entries.
You can add the routing entry with the following command:
route add -net 192.168.0.0 netmask 255.255.0.0 gw 192.168.0.100
You can add the default gateway with route command as shown below:
route add default gw 192.168.0.100
You can also delete the default gateway with the following command:
route del default gw 192.168.0.100
If you want to reject routing the packets to a particular host/network, run the following command:
route add -host 192.168.0.201 reject
Host is a simple command line utility for performing DNS lookups. It can be used to convert names to IP addresses and vice versa.
You can use host command without any argument gives a brief description about each option:
You can resolve domain name to IP address and IP address to domain name with the following command:
You can use host command with -t to see the NS records of domain google.com:
To print all the details of domain google.com with the following command:
ARP also known as “Address Resolution Protocol” is a very useful tool to find IP to MAC address mappings. It is also used to manipulates or displays the kernel’s IPv4 network neighbor cache.
Use arp without any argument will display the current content of the table.
You can find the MAC address of specific host with the following command:
You should see the following output:
Address HWtype HWaddress Flags Mask Iface
192.168.0.1 ether c8:3a:35:59:49:b0 C wlan0
You can list all the options available with arp command as shown below:
The ethtool is a command line tool to display and change the Ethernet adapter settings.
Using ethtool, you can change network card speed, auto-negotiation, duplex mode and wake on LAN setting.
You can use ethtool command with network interface card (enp0s3) to displays ethernet card properties as shown below:
You can also see driver information of network interface card (enp0s3) as shown below:
iwconfig is a command line tool that can be used to configure and manage your wireless network interface.
You can your wireless network information with the following command:
You can list all the options available with iwconfig as shown below:
hostname is a command line tool used to see the hostname of your system.
Run the following command to see the hostname of your system
You should see the following output:
You can list all the options available with hostname command as shown below:
You can see all the information about your host with the following command:
You should see the following output:
Static hostname: ubuntu1804
Icon name: computer-vm
Machine ID: 9ce42836ca1e4a63959b17e47fca28e8
Boot ID: 0a63735b83e746609eacb75652f34994
Operating System: Ubuntu 18.04.1 LTS
Kernel: Linux 4.15.0-47-generic
You can also set hostname of your system with the following command:
hostnamectl set-hostname newhostname
We hope you have now enough knowledge to use the above tools to manage and troubleshoot network related problems as well as connectivity issues within your servers.
These tools can help you to fix a network related problems in minimal time and we them on a daily basis when helping customers troubleshoot issues with their Linux and even windows Systems!