Networking

Networking configuration, diagnostics, and troubleshooting.

Checking open ports on a Linux system from the command line

Sep 2, 2026 • 11 min read

Check Open Ports in Linux: nmap, netcat, and Bash

Scan a Linux host or remote server for open ports with nmap, netcat, telnet, and Bash /dev/tcp, then distinguish closed ports from filtered connections.

Using the ss command to display socket statistics in Linux

Sep 2, 2026 • 12 min read

ss Command in Linux: Display Socket Statistics

Use the ss command to list TCP, UDP, and Unix sockets, filter by port and state, read queue columns, inspect timers, and replace common netstat commands.

Aug 28, 2026 • 13 min read

traceroute Command in Linux

Trace the path packets take to a host, read every field of the traceroute output, decode hops that show asterisks or !X, and map Windows tracert flags to Linux.

Aug 23, 2026 • 19 min read

dig Command in Linux: DNS Lookup

The dig command is a DNS lookup tool for querying name servers. This guide covers querying record types, reverse lookups, tracing resolution paths, and verifying DNSSEC.

Dig command querying DNS records in a Linux terminal

Aug 21, 2026 • 9 min read

DNS Record Types Explained: A, AAAA, CNAME, MX, TXT, and More

DNS record types map domains to servers, route email, publish verification data, and control certificate issuance. See zone-file examples and dig queries.

DNS record cards linking a domain to IP addresses, mail servers, and security policies

Jul 25, 2026 • 7 min read

How to Find Which Process Is Using a Port in Linux

Find the Linux process listening on a TCP or UDP port with ss, lsof, fuser, or netstat, then inspect and stop it safely.

Finding the process that is listening on a network port in Linux

Jul 24, 2026 • 6 min read

CIDR Notation and Subnetting Explained

CIDR notation defines IP network size with a prefix length. This guide explains subnet masks, address ranges, host counts, and practical IPv4 subnetting.

CIDR prefix dividing an IPv4 address into network and host bits

Jul 15, 2026 • 6 min read

How to Configure Networking with Netplan on Ubuntu

Configure Ubuntu networking with Netplan using practical YAML examples for DHCP, static IP addresses, DNS, Wi-Fi, bridges, and safe remote changes.

Configuring network interfaces on Ubuntu with Netplan YAML files

Jun 20, 2026 • 6 min read

TCP vs UDP: Differences and When to Use Each

Compare TCP vs UDP reliability, ordering, overhead, common ports, and use cases, with Linux ss commands for checking which transport a service uses.

Comparing the TCP and UDP transport protocols in Linux networking

Jun 14, 2026 • 6 min read

host Command in Linux: DNS Lookup

The host command is a simple DNS lookup tool. This guide covers forward and reverse lookups, querying specific record types, using a chosen name server, and reading the output.

Running DNS lookups with the host command in a Linux terminal

Jun 13, 2026 • 8 min read

IPv4 vs IPv6: Differences Explained

IPv4 and IPv6 are the two versions of the Internet Protocol. This guide explains how they differ in addressing, header format, and features, with a side-by-side comparison.

May 28, 2026 • 7 min read

Network Bandwidth Monitoring Tools: iftop, nload, bmon, and vnstat

Compare nload, iftop, bmon, and vnstat for checking Linux network bandwidth in real time and tracking historical traffic usage.

Command-line network bandwidth monitoring tools on Linux: iftop, nload, bmon, and vnstat

May 27, 2026 • 6 min read

localhost: 127.0.0.1 and Loopback Explained

Localhost is the hostname for your own computer. This guide explains how localhost, 127.0.0.1, ::1, loopback, /etc/hosts, and 0.0.0.0 work on Linux and other systems.

What is localhost and how the loopback interface works

May 25, 2026 • 8 min read

nslookup Command in Linux: Query DNS Records

The nslookup command queries DNS servers for domain records. This guide covers A, MX, NS, TXT, and AAAA lookups, reverse DNS, interactive mode, and choosing a specific name server.

nslookup command querying DNS records in a Linux terminal

May 25, 2026 • 7 min read

whois Command in Linux: Query Domain Registration Info

The whois command looks up domain registration, registrar, name server, expiry, IP allocation, and AS number details from Linux.

Querying domain registration with the whois command in Linux

May 17, 2026 • 7 min read

nmcli Command in Linux: NetworkManager CLI Reference

The nmcli command manages NetworkManager from the terminal. This guide covers device status, Wi-Fi connections, static IP configuration, DNS settings, and scripting-friendly output.