added subtopic about network utils

README_ENG.md

@@ -54,6 +54,7 @@ This repository is a visual cheatsheet on the main topics in Backend-development
   * [Permissions](#permissions)
   * [Working with processes](#working-with-processes)
   * [Working with SSH](#working-with-ssh)
+  * [Network utils](#network-utils)
   * [Task Scheduler](#task-scheduler)
   * [System logs](#system-logs)
   * [Linux problems](#linux-problems)
@@ -928,6 +929,58 @@ There are a huge number of Linux distributions (preinstalled software bundles) t
 
 <div align="right"><a href="#top">Contents ⬆️</a></div>
 
+-   ### Network utils
+
+    For Linux there are many built-in and third-party utilities to help you configure your network, analyze it and fix possible problems.
+
+    -   Simple utils
+        ```bash
+        ip address # show info about IPv4 and IPv6 addresses of your devices
+        ip monitor # real time monitor the state of devices
+        ifconfig # config the network adapter and IP protocol settings
+        traceroute <host> # show the route taken by packets to reach the host
+        tracepath <host> # traces the network host to destination discovering MTU
+        ping <host> # check connectivity to host
+        ss -at # show the list of all listening TCP connections
+        dig <host> # show info about the DNS name server
+        host <host | ip-address> # show the IP address of a specified domain
+        mtr <host | ip-address> # combination of ping and traceroute utilities
+        nslookup # query Internet name servers interactively
+        whois <host> # show info about domain registration
+        ifplugstatus # detect the link status of a local Linux ethernet device
+        iftop # show bandwidth usage
+        ethtool <device name> # show detalis about your ethernet device
+        nmap # tool to explore and audit network security
+        bmon # bandwidth monitor and rate estimator
+        firewalld # add, configure and remove rules on firewall
+        ipref # perform network performance measurement and tuning
+        speedtest-cli # check your network download/upload speed
+        wget <link> # download files from the Internet
+        ```
+    -   [`tcpdump`](https://en.wikipedia.org/wiki/Tcpdump)
+        > A console utility that allows you to intercept and analyze all network traffic passing through your computer.
+    -   [`netcat`](https://en.wikipedia.org/wiki/Netcat)
+        > Utility for reading from and writing to network connections using TCP or UDP. It includes port scanning, transferring files, and port listening: as with any server, it can be used as a [backdoor](<https://en.wikipedia.org/wiki/Backdoor_(computing)>).
+    -   [`iptables`](https://en.wikipedia.org/wiki/Iptables)
+        > User-space utility program that allows configure the IP packet filter rules of the Linux kernel firewall, implemented as different Netfilter modules. The filters are organized in different tables, which contain chains of rules for how to treat network traffic packets.
+    -   [`curl`](https://en.wikipedia.org/wiki/CURL)
+        > Command-line tool for transferring data using various network protocols.
+
+<details>
+    <summary>🔗 <b>References</b></summary>
+
+1. 📄 [**21 Basic Linux Networking Commands You Should Know**](https://itsfoss.com/basic-linux-networking-commands/)
+2. 📄 [**Using tcpdump Command in Linux to Analyze Network**](https://linuxhandbook.com/tcpdump-command/)
+3. 📺 [**tcpdump - Traffic Capture & Analysis** – YouTube](https://youtu.be/1lDfCRM6dWk)
+4. 📺 [**tcpdumping Node.js server** – YouTube](https://youtu.be/g_tmQ5G-T2w)
+5. 📄 [**Beginner’s guide to Netcat for hackers**](https://medium.com/@HackTheBridge/beginners-guide-to-netcat-for-hackers-55abe449991d)
+6. 📄 [**Iptables Tutorial**](https://linuxhint.com/iptables-tutorial/)
+7. 📄 [**An intro to cURL: The basics of the transfer tool**](https://blog.logrocket.com/an-intro-to-curl-the-basics-of-the-transfer-tool/)
+8. 📺 [**Basic cURL Tutorial** – YouTube](https://youtu.be/7XUibDYw4mc)
+ </details>
+
+<div align="right"><a href="#top">Contents ⬆️</a></div>
+
 -   ### Task Scheduler
 
     <p align="center"><img src="./files/linux/cron_eng.png" alt="cron"/></p>