Computers Flashcards
What does every computer need to connect to the internet?
A network interface card or a wifi card
What is a daemon?
a background process that handles requests for services such as print spooling and file transfers, and is dormant when not required.
What is the role of the network interface card?
A physical and data link layer device used by computers to connect and communicate with other devices on a LAN.
What is the role of the hub?
Hubs transfer data to all nodes connected to the hub, and not just the recipient nodes, while others discard the data as they are not the recipient.
causes data collisions
take up bandwidth
old technology which has been replaced with switches
What is the role of the switch?
A switch is more intelligent way of dealing with data as it forwards data but also filters it using MAC addresses.
Switch has a mac address table, which has all of the different MAC addresses and the ports they are connected to
Layer 2 device of OSI
Not all nodes connected to the switch receive the packets, but only the correct recipient
What is the role of the router?
Modern routers are exactly like switches and can create a bridge to WAN.
connects multiple different networks together, like the lan and the internet.
what is ARP? how can it be exploited?
ARP is used to discover MAC addresses, and an ARP request is sent out to every device on the network to ask whether it is the gateway.
Router responds with its MAC and then it is stored in the node’s ARP cache for future routing of data.
ARP cache’s can be poisoned by tricking devices into thinking that malicious devices are the gateway.
What is DHCP? How can it be exploited?
All devices need an IP address to communicate on the network, which is the role of DHCP.
DHCP discover packet is sent out on the first connection to a network to every device DHCP client (server) runs on a router, and runs the allocated IP server to the host which asked for the IP
DHCP IP addresses are not permanent and have an expiration until the device asks for another IP address allocation
on port 67-68
What is a shell?
A shell is something which communicates with the OS.
A terminal is needed to interact with a shell.
There are different types of shells
> bash
cmd
powershell
How does SSH work?
Secure Shell.
Often ran over TCP.
How does a reverse shell work?
It makes the victim device connect to the hacker.
It’s an outbound connection so it bypasses the firewall.
The hacker is listening on a particular address and port and is waiting for the victim to connect to their server.
What is Nmap used for?
Used to scan for network clients and the open ports on their machines. This is used to find vulnerabilities and to find specific applications running on the devices
It can be detected by intrusion detection systems,
so ping - it won't send packets to any of the clients # nmap -sp 192.100.1.1/24
Detect operating systems
nmap -O
What are cookies?
Cookies are small indentifiers unique to the user which web servers send to browsers. These cookies are sent back to the webserver each time you reconnect to a website. That is how the website remembers your preferences, what you do and what device you’re using.
