A one‑stop reference for commands, protocols, and troubleshooting tools. It covers Linux, Windows, and cloud‑related networking essentials, so you can quickly diagnose, configure, and secure networks.

Basic Network Configuration

• View IP & Interfaces
  • ifconfig (Linux, legacy)
  • ip addr show (modern Linux)
  • ip link show → Show interfaces
  • ip link set eth0 up/down → Enable/disable interface
  • ip route show → Display routing table
  • netsh interface ip show config (Windows)
• Assign IP Address
  • sudo ip addr add 192.168.1.10/24 dev eth0
  • ifconfig eth0 192.168.1.10 netmask 255.255.255.0

Connectivity & Troubleshooting

• Ping → Test reachability
  • ping google.com
  • ping -c 5 8.8.8.8 (Linux, 5 packets)
  • ping -t 8.8.8.8 (Windows, continuous)
• Traceroute → Trace packet path
  • traceroute google.com (Linux)
  • tracert google.com (Windows)
• MTR (My Traceroute) → Continuous path + latency
  • mtr google.com
• Telnet / nc (Netcat) → Test port connectivity
  • telnet host 80
  • nc -zv host 443

DNS & Host Resolution

• Check DNS Resolution
  • nslookup example.com
  • dig example.com
  • host example.com
• Flush DNS Cache
  • sudo systemd-resolve --flush-caches (Linux)
  • ipconfig /flushdns (Windows)

Routing & ARP

• Routing Table
  • route -n (Linux)
  • netstat -rn (Windows/Linux)
• Add Default Gateway
  • route add default gw 192.168.1.1
• ARP Cache
  • arp -n → Show ARP table
  • arp -d 192.168.1.100 → Delete entry

Network Performance Testing

• Bandwidth Test (iPerf)
  • iperf3 -s → Start server
  • iperf3 -c <server_ip> → Run client test
• Packet Capture
  • tcpdump -i eth0 → Capture packets
  • tcpdump -i eth0 port 80 → Filter by port
  • wireshark → GUI packet analysis

Security & Firewalls

• Linux Firewall (iptables/nftables)
  • iptables -L → List rules
  • iptables -A INPUT -p tcp --dport 22 -j ACCEPT → Allow SSH
  • nft list ruleset → Modern firewall
• Windows Firewall
  • netsh advfirewall show allprofiles
  • netsh advfirewall firewall add rule name="AllowSSH" dir=in action=allow protocol=TCP localport=22

Wireless & Interfaces

• Wireless Config
  • iwconfig → Show wireless interfaces
  • iwlist wlan0 scan → Scan Wi‑Fi networks
• Hostname
  • hostname → Show hostname
  • sudo hostnamectl set-hostname newname

Debugging Labs

1. Connectivity Check → ping + traceroute
2. DNS Failure → dig + nslookup
3. Port Blocked → nc -zv host port
4. Packet Loss → mtr + iperf3
5. Suspicious Traffic → tcpdump + wireshark

Quick Recap

• Ping/Traceroute = Reachability & path.
• DNS Tools = Name resolution.
• Route/ARP = Path & neighbor discovery.
• iPerf/tcpdump/Wireshark = Performance & packet analysis.
• Firewalls = Security enforcement.