Linux and Networking Commands Basics

Basic Linux Commands

• ls command lists directory contents
• cd command changes the directory
• pwd command prints the working directory
• cp command copies files/directories
• mv command moves/renames files/directories
• rm command removes files/directories
• chmod command changes file mode bits (permissions)
• chown command changes file owner and group
• grep command searches text using patterns

Networking Commands

• ifconfig and ip addr commands display network interfaces and IP addresses
• ping command checks connectivity to a host
• netstat command displays network connections, routing tables, and interface statistics
• ss command is a utility to investigate sockets
• traceroute command traces the route packets take to a network host
• nslookup and dig commands query Internet name servers for DNS information

Ports and Protocols

• HTTP uses port 80 for web traffic
• HTTPS uses port 443 for secure web traffic
• FTP uses port 21 for file transfers
• SSH uses port 22 for secure remote administration
• SMTP uses port 25 for email sending
• DNS uses port 53 for domain name resolution
• DHCP uses ports 67 and 68 for network device configuration
• RDP uses port 3389 for Windows remote desktop access

TCP and UDP Protocols

• TCP (Transmission Control Protocol) is a connection-oriented protocol, ensuring messages are delivered in order and checks for errors, like making a phone call
• UDP (User Datagram Protocol) is a connectionless protocol, sending data without establishing a connection, making it faster but without guarantees for delivery or order, suitable for streaming where speed is preferred over reliability