Linux
Disk Tools
df: display free disk space
- df -a Show all mount points
- df -h "Human-readable" output
fdisk: partition maintenance program
- fdisk -l List partitions
- fdisk /dev/sda Start the partition manipulator
- fdisk -l /dev/sda View the /dev/sda disk partitions
- fdisk -s /dev/sda2 Check the size of a specific partition
Performance Tools
free: outputs a summary of RAM usage
- free -m Display memory in megabytes
- free -h Display memory figures in human-readable form
- free -t Display a total of all memory figures in each column
- free -s 3 keep a gap of 3 seconds
- free -s 3 -c 5 run only a set number of times
lsof: list all files opened by running processes
- lsof -u username List of all opened files of user
- lsof -i TCP:port Find out all the running process of specific port
- lsof -p pid Find out all the running process of specific PID
- lsof -i4 List all IPv4 network files
- lsof -i6 List all IPv6 network files
- lsof -i List all open sockets
- lsof /path List all processes accessing a particular file/directory
Other
- top Showing the active processes and other system information
- htop A newer program compared to top command
- ctop Provides a concise and condensed overview of real-time metrics for multiple containers
- vmstat -a Report virtual memory statistics
Network Tools
dig: querying DNS name servers
- dig google.com Query Domain “A” Record
- dig google.com +short Drastically cut the output
- dig google.com MX Query MX Record
- dig google.com TTL Query TTL Record
- dig google.com ANY +noall +answer Query ALL DNS Records
- dig -x 72.30.38.140 +short DNS Reverse Look-up
- dig @dns_server host lookups at DNS Server
- dig +trace host Lookup with trace
ip: configuring network interfaces
- ip addr Display all interfaces with addresses
- ip link set dev wlan0 {up|down} Take down/up the wireless adapter
- ip addr add 192.168.1.100/32 dev eth0 Set a static IP and netmask
- ip address flush dev eth0 Remove all IPs from an interface
- ip route Display all routes
- ip -6 route Display all routes for IPv6
- ip route add default via 192.168.1.1 Add default route via gateway IP
- ip route add 192.168.0.0/24 dev eth0 Add route via interface
- ip route get to 8.8.8.8 Get the route used for an destination
- ip link set dev eth0 address aa:bb:cc:dd:ee:ff Change your mac address
- ip neighbor show View neighbors (using ARP and NDP)
nmap: security & network scanner
- nmap host Simple target scan
- nmap -iL list.txt Scan from a list of targets
- nmap -O --osscan_guess host OS detection
- nmap -oN output.txt host Save output to text file
- nmap -source-port port host Scan a specific port
- nmap -A host Do an aggressive scan
- nmap -traceroute host Traceroute
- nmap -sP 192.168.0.0/24 Ping scan all machines on a class C network
- nmap -p 22 192.168.0.0/24 Scan for available SSH connections
other
- iptraf Real-time statistics in ncurses interfaces
- mtr --report host Debug routing/package loss issues
- arp -a Address resolution display and control
- route -n Displays and manipulates the routing table
- hostname host|ip Displays the domain name for a given IP address and IP address for a given hostname
- whois domain Fetch all the information related to a website
- tcpdump Captures the traffic that is passing through the network interface and displays it