network-tools

# Network Tools and Diagnostics ## Overview Linux network diagnostics, port scanning, traffic analysis and other tool usage skills. ## Network Configuration ### View Configuration ```bash # IP address ip addr ip a ifconfig # Legacy command # Routing table ip route route -n netstat -rn # DNS configuration cat /etc/resolv.conf systemd-resolve --status ``` ### Configure Network ```bash # Temporary IP configuration ip addr add 192.168.1.100/24 dev eth0 ip addr del 192.168.1.100/24 dev eth0 # Enable/Disable interface ip link set eth0 up ip link set eth0 down # Add route ip route add 10.0.0.0/8 via 192.168.1.1 ip route del 10.0.0.0/8 ``` ## Connectivity Testing ### ping ```bash ping hostname ping -c 4 hostname # Send 4 packets ping -i 0.2 hostname # 0.2 second interval ping -s 1000 hostname # Specify packet size ``` ### traceroute ```bash traceroute hostname traceroute -n hostname # Don't resolve hostnames traceroute -T hostname # Use TCP mtr hostname # Real-time trace ``` ### DNS Query ```bash nslookup hostname dig hostname dig +short hostname dig @8.8.8.8 hostname # Specify DNS server host hostname ``` ## Ports and Connections ### ss Command (Recommended) ```bash # Listening ports ss -tlnp # TCP listening ss -ulnp # UDP listening ss -tlnp | grep :80 # All connections ss -tanp ...