What is the Linux command S that will tell you the interface name of the network interface device used to route the ICMP ping packets to www Google com?

A system administrator’s routine tasks include configuring, maintaining, troubleshooting, and managing servers and networks within data centers. There are numerous tools and utilities in Linux designed for administrative purposes.

In this article, we will review some of the most used command-line tools and utilities for network management in Linux, under different categories. We will explain some common usage examples, which will make network management much easier in Linux.

This list is equally useful to full-time Linux network engineers.

Network Configuration, Troubleshooting, and Debugging Tools

1. ifconfig Command

ifconfig is a command-line interface tool for network interface configuration and is also used to initialize interfaces at system boot time. Once a server is up and running, it can be used to assign an IP Address to an interface and enable or disable the interface on demand.

It is also used to view the IP Address, Hardware / MAC address, as well as MTU (Maximum Transmission Unit) size of the currently active interfaces. ifconfig is thus useful for debugging or performing system tuning.

Here is an example to display the status of all active network interfaces.

To list all interfaces which are currently available, whether up or down, use the -a flag.

To assign an IP address to an interface, use the following command.

To activate a network interface, type.

To deactivate or shut down a network interface, type.

Note: Although ifconfig is a great tool, it is now obsolete (deprecated), its replacement is the ip command which is explained below.

2. IP Command

ip command is another useful command-line utility for displaying and manipulating routing, network devices, interfaces. It is a replacement for ifconfig and many other networking commands. (Read our article “What’s Difference Between ifconfig and ip Command” to learn more about it.)

The following command will show the IP address and other information about a network interface.

To temporarily assign IP Address to a specific network interface (eth0), type.

To remove an assigned IP address from a network interface (eth0), type.

To show the current neighbor table in the kernel, type.

3. ifup, ifdown, and ifquery command

ifup command actives a network interface, making it available to transfer and receive data.

ifdown command disables a network interface, keeping it in a state where it cannot transfer or receive data.

ifquery command used to parse the network interface configuration, enabling you to receive answers to query about how it is currently configured.

4. Ethtool Command

ethtool is a command-line utility for querying and modifying network interface controller parameters and device drivers. The example below shows the usage of ethtool and a command to view the parameters for the network interface.

5. Ping Command

ping (Packet INternet Groper) is a utility normally used for testing connectivity between two systems on a network (Local Area Network (LAN) or Wide Area Network (WAN)). It uses ICMP (Internet Control Message Protocol) to communicate to nodes on a network.

To test connectivity to another node, simply provide its IP or hostname, for example.

You can also tell ping to exit after a specified number of ECHO_REQUEST packets, using the -c flag as shown.

6. Traceroute Command

Traceroute is a command-line utility for tracing the full path from your local system to another network system. It prints a number of hops (router IPs) in that path you travel to reach the end server. It is an easy-to-use network troubleshooting utility after the ping command.

In this example, we are tracing the route packets take from the local system to one of Google’s servers with IP address 216.58.204.46.

7. MTR Network Diagnostic Tool

MTR is a modern command-line network diagnostic tool that combines the functionality of ping and traceroute into a single diagnostic tool. Its output is updated in real-time, by default until you exit the program by pressing q.

The easiest way of running mtr is to provide it a hostname or IP address as an argument, as follows.

Sample Output

You can limit the number of pings to a specific value and exit mtr after those pings, using the -c flag as shown.

8. Route Command

The route is a command-line utility for displaying or manipulating the IP routing table of a Linux system. It is mainly used to configure static routes to specific hosts or networks via an interface.

You can view the Kernel IP routing table by typing.

There are numerous commands you can use to configure routing. Here are some useful ones:

Add a default gateway to the routing table.

Add a network route to the routing table.

Delete a specific route entry from the routing table.

9. Nmcli Command

Nmcli is an easy-to-use, scriptable command-line tool to report network status, manage network connections, and control the NetworkManager.

To view all your network devices, type.

To check network connections on your system, type.

To see only the active connections, add the -a flag.

Network Scanning and Performance Analysis Tools

10. Netstat Command

netstat is a command-line tool that displays useful information such as network connections, routing tables, interface statistics, and much more, concerning the Linux networking subsystem. It is useful for network troubleshooting and performance analysis.

Additionally, it is also a fundamental network service debugging tool used to check which programs are listening on what ports. For instance, the following command will show all TCP ports in listening mode and what programs are listening on them.

To view the kernel routing table, use the -r flag (which is equivalent to running the route command above).

Note: Although Netstat is a great tool, it is now obsolete (deprecated), its replacement is the ss command which is explained below.

11. ss Command

ss (socket statistics) is a powerful command-line utility to investigate sockets. It dumps socket statistics and displays information similar to netstat. In addition, it shows more TCP and state information compared to other similar utilities.

The following example shows how to list all TCP ports (sockets) that are open on a server.

To display all active TCP connections together with their timers, run the following command.

12. NC Command

NC (NetCat) also referred to as the “Network Swiss Army knife”, is a powerful utility used for almost any task related to TCP, UDP, or UNIX-domain sockets. It is used to open TCP connections, listen on arbitrary TCP and UDP ports, perform port scanning plus more.

You can also use it as a simple TCP proxy, for network daemon testing, to check if remote ports are reachable, and much more. Furthermore, you can employ nc together with pv command to transfer files between two computers.

[ You might also like: 8 Netcat (nc) Command with Examples ]

The following example will show how to scan a list of ports.

You can also specify a range of ports as shown.

The following example shows how to use nc to open a TCP connection to port 5000 on server2.tecmint.lan, using port 3000 as the source port, with a timeout of 10 seconds.

13. Nmap Command

Nmap (Network Mapper) is a powerful and extremely versatile tool for Linux system/network administrators. It is used to gather information about a single host or explores networks an entire network. Nmap is also used to perform security scans, network audits and finding open ports on remote hosts and so much more.

You can scan a host using its hostname or IP address, for instance.

Alternatively, use an IP address as shown.

Read our following useful articles on the nmap command.

DNS Lookup Utilities

14. host Command

host command is a simple utility for carrying out DNS lookups, it translates hostnames to IP addresses and vice versa.

15. dig Command

dig (domain information groper) is also another simple DNS lookup utility, that is used to query DNS related information such as A Record, CNAME, MX Record etc, for example:

16. NSLookup Command

Nslookup is also a popular command-line utility to query DNS servers both interactively and non-interactively. It is used to query DNS resource records (RR). You can find out the “A” record (IP address) of a domain as shown.

You can also perform a reverse domain lookup as shown.

Linux Network Packet Analyzers

17. Tcpdump Command

Tcpdump is a very powerful and widely used command-line network sniffer. It is used to capture and analyze TCP/IP packets transmitted or received over a network on a specific interface.

To capture packets from a given interface, specify it using the -i option.

To capture a specific number of packets, use the -c option to enter the desired number.

You can also capture and save packets to a file for later analysis, use the -w flag to specify the output file.

18. Wireshark Utility

Wireshark is a popular, powerful, versatile, and easy-to-use tool for capturing and analyzing packets in a packet-switched network, in real-time.

You can also save data it has captured to a file for later inspection. It is used by system administrators and network engineers to monitor and inspect the packets for security and troubleshooting purposes.

19. Bmon Tool

bmon is a powerful, command line-based network monitoring and debugging utility for Unix-like systems, it captures networking-related statistics and prints them visually in a human-friendly format. It is a reliable and effective real-time bandwidth monitor and rate estimator.

Linux Firewall Management Tools

20. Iptables Firewall

iptables is a command-line tool for configuring, maintaining, and inspecting the tables IP packet filtering and NAT ruleset. It is used to set up and manage the Linux firewall (Netfilter). It allows you to list existing packet filter rules; add or delete or modify packet filter rules; list per-rule counters of the packet filter rules.

You can learn how to use Iptables for various purposes from our simple yet comprehensive guides.

21. Firewalld

Firewalld is a powerful and dynamic daemon to manage the Linux firewall (Netfilter), just like iptables. It uses “networks zones” instead of INPUT, OUTPUT, and FORWARD CHAINS in iptables. On current Linux distributions such as RHEL/CentOS 7 and Fedora 21+, iptables is actively being replaced by firewalld.

To get started with firewalld, consult these guides listed below:

Important: Iptables is still supported and can be installed with the YUM package manager. However, you can’t use Firewalld and iptables at the same time on the same server – you must choose one.

22. UFW (Uncomplicated Firewall)

UFW is a well-known and default firewall configuration tool on Debian and Ubuntu Linux distributions. It is used to enable/disable system firewall, add/delete/modify/reset packet filtering rules, and much more.

To check UFW firewall status, type.

If the UFW firewall is not active, you can activate or enable it using the following command.

To disable the UFW firewall, use the following command.

Read our article How to Setup UFW Firewall on Ubuntu and Debian.

If you want to find more information about a particular program, you can consult its man pages as shown.

That’s all for now! In this comprehensive guide, we reviewed some of the most used command-line tools and utilities for network management in Linux, under different categories, for system administrators, and equally useful to full-time network administrators/engineers.

You can share your thoughts about this guide via the comment form below. If we have missed any frequently used and important Linux networking tools/utilities or any useful related information, also let us know.