Networking Flashcards
What is the OSI model?
A way of thinking about networking operations. If there is an issue with one layer then the message will not get through. Can be used in troubleshooting.
What are the 7 layers of the OSI model?
Please Do Not Throw Sausage Pizza Away
Physical- CAT5, fibre optic cable Data link- MAC Network- IP, ARP Transport- TCP Session- Setup, negotiation Presentation- TLS/SSL, compression Application- Web browser
What does the application layer do?
Interprets the messages in HTTP protocol and renders HTML
Does AWS allow multicast?
No
What is unicast?
one on one conversation between servers
like a phone call
What is multicast?
When a network card/server sends messages to everyone on a network- layer 2 (MAC)
What are the 3 main communication protocols used in AWS networking?
1) TCP (layer 4)
2) UDP (layer 4)
3) ICMP (layer 3)
What are the characteristics of TCP and its common uses?
A connection-based stateful communication protocol that acknowledges receipt
e.g. web, email or file transfer
What are the characteristics of UDP and its common uses?
Connectionless stateless with no transmission delays
e.g. streaming media, DNS (why… it’s simple)
What are the characteristics of ICMP and its common uses?
Used by network devices to exchange information
e.g. Traceroute, ping
What is an ephemeral port?
A short-lived transport protocol port used in IP communication
What port ranges are used for ephemeral ports?
Suggested range = 49152 to 65535
linux generally use 32568 to 61000
windows default from 1025
Who defines the ephemeral port number during TCP communication?
The client! e.g. Dial on port 80 (HTTP) and use port 56784 to respond…
Which protocols use ephemeral ports to transfer data?
1) TCP
2) UDP
Why use UDP instead of TCP for large streaming data?
Because there is no acknowledgement. Acknowledging every receipt during streaming would be burdensome
How many IP addresses are reserved in an AWS VPC and what are they? and what are they used for?
5
1) 10.0.0.0- Network address
2) 10.0.0.1- Reserved for AWS for the VPC router
3) 10.0.0.2- Reserved for Amazon DNS
4) 10.0.0.3- Reserved for future use
5) 10.0.0.255- VPCs do no support broadcast for AWS reserves this
Are the reserved IP addresses tied to a specific IP addresses (or numbers)?
No, the IP number doesn’t matter, it is the position in the address that matters!
What consideration do you need to make when creating a VPC?
Ensure that you have enough IP addresses available
e. g. 10.0.0.0/16 ~
10. 0.0.0/32
How many IP addresses will be available for the CIDR block 10.0.0.0/28?
16
How many IP addresses will be available for the CIDR block 10.0.0.0/16?
65536
What are the 8 methods of connecting on-prem network with a VPC?
1) AWS managed VPN
2) AWS managed VPN-Redundant
3) AWS Direct Connect
4) AWS Direct Connect plus VPN
5) AWS VPN Cloud Hub
6) Software VPN
7) Transit VPC
What, when, pros and cons of…. AWS managed VPN
What- iPsec VPN connection
when- want quick and easy, secure connection to a VPC, can be used as a redundant link for direct connect
Pros- Supports static routes or BGP peering and routing
Cons- Dependent on internet connection
What are the 5 steps to set up a AWS managed VPN?
1) Designate an appliance to act as your customer gateway, this is usually your on-prem router
2) Create the VPN connection in AWS and download the config file for your customer gateway
3) Configure your customer gateway using the information from the config file e.g. IPSEC encryption
4) Generate traffic from your side of the VPN connection to bring up the VPN tunnel
5) Configure BGP routing if required
What, when, pros and cons of…. AWS managed VPN- redundant
what- secondary VPN connection
when- want additional redundancy for your AWS VPN
pros- provides redundant architecture
cons- You will have to manually deal with failover, additional cost?
What, when, pros and cons of…. AWS Direct connect
What- Dedicated network connection over PRIVATE lines straight into AWS backbone
when- When you require a “big pipe” into AWS, lots of resources or services being provided on AWS to your corporate users
Pros- More predictable network performance up to 10Gbps connections, supports BGP peering and routing
cons- may require additional telecom and hosting provider relationships and or new network circuits
How do you set up AWS Direct Connect?
Work with your existing provider, create a virtual interface (VIF) to connect a VPC (private VIF) or to other AWS services like S3 (public VIF)
How would you increase the redundancy of a direct connect connection?
You would need to set up a second direct connect connection, ideally using a different provider
What, when, pros and cons of…. Direct connect plus VPN
what- IPSEC VPN connection over private lines
when- Want added security of an encrypted tunnel over direct connect
pros- More secure (in theory) than direct connect alone
cons- more complexity by adding a VPN layer
How would you set up a Direct Connect plus VPN connection?
Organise this through your existing data networking provider
What, when, pros and cons of…. AWS VPN CloudHub
what-Connect locations in a hub and spoke manner using AWS’s virtual private gateway
when- If you wanted to link remote offices for back-up or primary WAN access to AWS resources and each other
pros- Uses existing internet connection, iPSEC VPN connection, support BGP routes to direct traffic e.g. uses MPLS first then Cloud Hub VPN as a backup
cons- Dependent on internet connection; no inherent redundancy
How would you set up a AWS VPN CloudHub
1) create single virtual private gateway
2) create multiple customer gateways, each with the public IP address of the gateway. You must use unique BGP ASNs for each customer gateway
3) Create dynamically routed site-to-site VPN connection from each customer gateway to the common virtual gateway
4) configure the customer gateway devices to advertise a site-specific pre-fix (e.g. 10.0.0.0/24, 10.0.1.0) to the virtual private gateway. These routing advertisements are received and re-advertised to each BGP peer, enabling each site to send data to and receive data from the other sites
5) configure the routes in your subnet route table to enable instances in your VPC to communicate with your sites
What, when, pros and cons of…. software VPN
What- You provide your own VPN endpoints and software
when- When you must manage both ends of the VPN connection for compliance reasons you want to use a VPN option not supported by AWS e.g. openVPN
Pros- Ultimate flexibility and manageability
cons- You must design for any needed redundancy across the whole chain
How would you go about setting up a software VPN?
Install the VPN software via a market place appliance or on an EC2 instance
What, when, pros and cons of…. Transit VPC?
What- common strategy for connecting geographically disperse VPCs and locations in order to create a global network transit center
when- locations and VPC-deployed assets across multiple regions that need to communicate with one another
pros- ultimate flexibility and manageability but also AWS-managed VPN hub and spokes between VPCs, good for one VPC as a pass through and to deploy across different cloud providers
cons- You must design for any redundancy across the whole chain
How do you set up a transit VPC?
Contact provider such as cisco that link their equipment with an AWS VPC
What are the two types of VPC to VPC connections?
1) VPC peering
2) AWS private link
What, when, pros and cons of….VPC peering
What- AWS provided network connectivity between 2 VPCs
when- When you have multiple VPCs that need to communicate or access each others resources
pros- Uses AWS’s backbone without touching the internet
cons- Does not support transitive peering
How do you set up VPC peering?
You make a VPC peering request, acceptor accepts!
What, when, pros and cons of…. AWS private link?
What- AWS provided network connectivity between VPCs and or AWS services using interface endpoints
when- When you want to keep private subnets truely private by using the AWS backbone to reach the services rather than the public internet.
Pros- Redundant as it uses AWS backbone
cons- cost? time to set up manually?
How do you create an AWS private link?
Create endpoints for needed AWS or marketplace services in all needed subnet, access these via the provided DNS hostname
What are the 2 types of endpoints in AWS?
1) Interface endpoint
2) Gateway endpoint