Networking and Linux Commands Practice

Vocabulary-style flashcards covering network troubleshooting commands, Windows/Linux utility syntax, package management, and file permissions based on lecture notes.

ping

A command that tests network connectivity using ICMP packets.

ping -t

A command that sends ICMP packets to a target until manually stopped.

ping -a

A command that resolves addresses to hostnames.

ping -n

A command that specifies the number of ICMP packets to send.

ping -

A command that specifies the packet size in bytes.

tracert

A Windows command that shows the path a packet takes to its destination.

traceroute

A Linux command that shows the path a packet takes to its destination.

Hop

Each device a packet passes through on its path to the destination.

pathping

A Windows command that combines the functionality of tracert and ping.

netstat

Displays network statistics including connections, open ports, and running programs.

netstat -a (Windows)

Displays all connections and listening ports in Windows.

netstat -b (Windows)

Displays the executable involved in creating each connection or listening port in Windows.

netstat -f (Windows)

Displays the FQDN (Fully Qualified Domain Name) for the foreign address when possible.

netstat -r

Displays the routing table.

netstat -p

Shows connections for a specified protocol such as TCP or UDP.

route

A command that shows the routing table in both Windows and Linux.

arp

A command that displays, adds, and removes ARP information, matching addresses to MAC addresses.

arp -a

Displays current ARP entries.

arp -d

Deletes the host specified by the internet address.

nslookup

A command used for DNS lookups in Windows to provide DNS server information, IP addresses, and domain names.

dig

A command used for DNS lookups in Linux.

ipconfig

A Windows command that displays local IP configuration, such as MAC address, IPv4/IPv6 address, and default gateway.

ifconfig

A Linux command that displays local IP configuration.

hping

A security tool used to check connectivity and analyze a target by sending ICMP, TCP, UDP, and RAW-IP packets.

netcat

A tool that can read and write data across TCP and UDP connections; it can create connections, send packets, and scan or listen on ports.

nmap

A network security scanner used to discover information such as open ports, running services, and operating system information.

nmap-ST

The Nmap command used to scan TCP ports.

nmap -SU

The Nmap command used to scan UDP ports.

yum list installed / dnf list installed

Commands used to list installed RPM packages.

apt autoremove

Automatically removes unused packages in Linux.

apt list

Lists installed packages in Linux.

dpkg get-selections

Displays installed Debian package selections.

yum erase packagename

The command to remove a package using yum.

systemctl --type-service-state-active

A command that shows active Linux services.

systemctl stop servicename

A command that immediately stops a Linux service.

man

A command used to research an unfamiliar Linux command or service.

apt-i nmap

The command used to install Nmap with apt according to the course.

netstat/ss -I

A Linux socket checking option that lists listening sockets.

netstat/ss -s

A Linux socket checking option that displays statistics for each protocol.

iptables

A Linux firewall utility that uses policy chains (INPUT, FORWARD, OUTPUT) and rules to allow or block network traffic.

iptables ACCEPT action

Allows the connection through the firewall.

iptables DROP action

Drops the connection without sending a response to the sender.

iptables REJECT action

Rejects the connection and sends a response to the sender.

sudo iptables -L

Lists current iptables rules.

sudo iptables -F

Clears (flushes) current iptables rules.

r (read)

Linux permission to access/view file contents or list directory contents; value is $4$.

w (write)

Linux permission to save changes or create/rename/delete files; value is $2$. Deleting or renaming directories also requires execute.

x (execute)

Linux permission to run a program/script or access a directory; value is $1$.

chmod $755$ home

Sets permissions where owner/user = rwx, group = r-x, and others = r-x.

/etc/passwd

The location where local Linux user account names are stored.

/etc/shadow

The location where Linux password hashes are stored.

passwd -I username

Locks the specified user account.

usermod -aG

Appends a user to a secondary group while retaining existing secondary group memberships.

userdel -r username

Removes the user account and the user's home directory.

ssh-keygen-tra

The command that creates an SSH RSA key pair according to the transcript.

SCP

Secure Copy; a command used to securely copy files using SSH protocol.

HTTPS

A secure form of HTTP that uses SSL or TLS to encrypt data; uses TCP port $443$.

SFTP

A secure file transfer protocol that uses SSH version $2$ to secure data transfers.

FTPS

FTP secured with SSL/TLS; it requires a server certificate.

TFTP

A file transfer protocol that uses UDP and provides no authentication, encryption, or error detection.