Week 8 - Net Flashcards
What does DHCP stand for?
Dynamic host configuration protocol
What does DHCP allow?
automated address assignment
Do clients have public or private addresses?
private, used with NAT
Do clients need DNS entry?
No
Do servers need a DNS entry?
Yes, as clients lookup the server address
What is dynamic configuration?
automatically assigned address “leasing” from a pool of addresses
Does DHCP use LAN or WAN?
LAN broadcast
What is DHCP useful for?
- nomadic devices
- large number of hosts
Process of DHCP?
- client broadcasts message
- both servers broadcast reply
- broadcast confirmation; server B chosen
What is routing? In terms of an IP router?
– the process of discovering paths through the network,
gathering routing information, using a routing protocol
-– A metric value (a “cost”) is assigned to each route
What is forwarding? In terms of an IP router?
– the process of transmitting packets using the discovered
routing information.
What is forwarding? In terms of an IP host?
– discover locally available route(s) for destinations
– make local forwarding decisions.
what is a destination
another network
What is used to choose the route for forwarding?
longest prefix match
How does longest prefix match work?
- apply network mask of routing entry to destination address in packet
- the longest mask that produces a match between the local forwarding entry and destination address is used
What to use if no prefix matches?
default route
what does NAT stand for?
network address translation
What is NAT?
process where a network device, assigns a public address to a computer inside a private network
What is the main use of NAT?
to limit the number of public IP addresses an organization or company must use, for both economy and security purposes.
Describe some problems with NAT?
- lose end-to-end model
- makes end-to-end security harder
- single point of failure
What does a firewall prevent?
- packets leaving site network
- packets entering site network
where is a firewall situated?
border router
What are some on the wire threats?
eavesdropping
traffic modification
- modification of genuine packets
man in the middle
Explain symmetric cryptography?
single key
used for both encyprtion and decryption
must be known and kept secure by both parties
explain public key cyrptography?
paired keys
different keys but complimentary
What does a hash algorithm do?
creates a fixed size bit pattern from any input of bits
properties of a hash algorithm?
- fixed size hash value as output
- cannot reporudce original message from hash
- Very low probability of
producing two messages with
the same hash.
explain message authentication codes
sender sends message and MAC
reciever recieves message and MAC, and encrypts using their key and check if both MAC’s match to ensure no tampering
how does digital checksum work?
Signature - public key:
– create hash
– encrypt with kS
– check at receiver using kP
What does TLS stand for?
transport layer security
What does TLS allow?
- client to authenticate server, and vise versa
- client and server to select crypto protocols for use over a communication session
- client and server to exchange keys securely
- confidential sessions between client and server
