ifconfig Basics: Viewing and Modifying Network Settings on Linux/macOS

 Ifconfig (Linux)

ifconfig (short for interface configuration) is a command-line utility used in Unix-like operating systems, including Linux, macOS, and BSD, to configure, control, and query network interface parameters. Here are some key points about ifconfig:

Functionality: It allows users to set IP addresses, subnet masks, and enable or disable network interfaces. It can also be used to view the current configuration of network interfaces.

Usage: Common commands include ifconfig to display all active interfaces, ifconfig [interface] up to enable an interface, and ifconfig [interface] down to disable an interface.

Deprecation: In many modern Linux distributions, ifconfig has been deprecated in favor of the ip command from the iproute2 package, which offers more features and better support for modern networking needs.

ext3 & ext4

 ext3 vs ext4

Ext4 is an advanced version of the ext3 file system for Linux that offers several improvements, including:

File and partition sizes:

Ext4 supports files up to 16 terabytes and partitions up to 1 exabyte, while ext3 supports files up to 2 terabytes and partitions up to 16 terabytes.

Sub-directories:

Ext4 supports unlimited sub-directories, while ext3 only supports up to 32,000.

Performance:

Ext4 is faster due to extents, contiguous blocks of data, and delayed allocation, which optimizes write operations.

Reliability:

Ext4 is more reliable due to checksums for the journal and metadata, as well as multi-block allocation.

Flexibility:

Ext4 has more flexibility with subvolumes and online defragmentation.

Scalability:

Ext4 is designed to support large file systems and keep up with increasing disk capacities.

Ext3 was the default file system for many Linux distributions, but ext4 is now the default for many.

Netstat - Native to Linux / Windows

 NETSTAT

Netstat is a tool built into both Linux and Windows, but the syntax is different between the two operating systems.

Several ways this local command line tool can be utilized:

• See what ports (services) are in a listening state, both TCP and UDP ports.
• See what files are being accessed and which computers are involved.
• See if any systems are connected before rebooting a server.
• See what process established the connection (such as Zoom, Firefox, Chrome, Edge, etc.)
• Display ethernet statistics
• Display the owning process ID
• Display the routing table

LINUX CLI COMMANDS

Here are the Linux commands that you will need to know for the exam:

cd: change directory - Allows a user to change between directories

chmod: Changes the permissions on the files listed

chown: Allows you to change group & user of a file

cp: copy - Allows a user to make a copy of a file

grep: Search feature to look for a string of text

head: outputs the first 10 lines of a file

locate: this is the find command, used to locate a file

logger: writes input to the local system log or to a remote syslog server

ls: Shows the user a list of the files in the current directory

man: manual - Will show all the information about a particular command

mkdir: make directory - Allows a user to make a new folder or directory

mv: move - Allows a user to move a file to another directory or folder

passwd: changes the users' password

ps: Allows the user to see the processes running on the PC/Server

pwd: Allows a user to know the name of the directory in which they are located

rm: remove - This command allows a user to remove files within a directory

rmdir: remove directory: Allows a user to remove a folder or directory

tail: outputs the last 10 lines of a file

LINUX PERMISSIONS

Linux permission attributes:

r (read)                                                        View file content

w (write)                                                     Modify file content

x (execute)                                                  Run a file (if it's an executable program & is combined
                                                                    with the read attribute)


An example of Linux permissions:

rwxrwxrwx

The first 3 belong to the user or owner: Owner level rwx: Owner can read, write & execute the file

The second 3 belong to the group: Group-level rwx: only members of the group to which the file belongs can read, write, & execute the file

The last 3 belong to other or world: Other level rwx: All users can read, write and execute

To change file permissions using the CLI, you would use "chmod"

Permissions example: rwxrw-r--

The owner has read, write, execute

Groups have read, write

Other have read