Network Connectivity & Security Tools

Overview

Linux is packed with powerful networking and security tools. This section covers the essential utilities you'll use to connect, diagnose, and secure your system.

Essential Networking Tools

🔑

OpenSSH

Secure Shell — encrypted remote login and file transfer. Replace telnet and FTP with this immediately. ssh user@host, scp file user@host:/path.

🔍

nmap

Network port scanner. Use it to find open ports on your own machine or network. nmap -sT localhost. Essential for security auditing.

📡

tcpdump

Command-line packet analyser. Capture and inspect network traffic in real time. tcpdump -i eth0 port 80.

🌐

netcat (nc)

The "Swiss Army knife" of networking. Create TCP/UDP connections, port scan, transfer files, banner grabbing. nc -zv host 22.

🔒

GnuPG (GPG)

GNU Privacy Guard — encrypt and sign files and email. gpg --gen-key to create your keypair.

Useful One-liners

$ ssh-keygen -t rsa          # generate SSH key pair
$ ssh-copy-id user@host       # install your pub key on remote
$ nmap -sT -O 192.168.1.0/24 # scan local network
$ tcpdump -i eth0 -w cap.pcap # capture to file
$ gpg -e -r name file.txt     # encrypt a file