Basic Linux and Networking Commands

Basic Linux Commands

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

Networking Commands

• ifconfig/ip addr command displays 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/dig command queries Internet name servers for DNS information.

Network Protocols and Ports

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

TCP and UDP

• TCP is a connection-oriented protocol, ensuring messages are delivered in order and checks for errors, similar to making a phone call.
• UDP is a connectionless protocol, sent without establishing a connection, making it faster but without guarantees for delivery or order, suitable for streaming where speed is preferred over reliability.