mirror of
https://github.com/jackyzha0/quartz.git
synced 2025-12-28 07:14:05 -06:00
138 lines
4.3 KiB
Markdown
138 lines
4.3 KiB
Markdown
---
|
|
title: "25-network-security-2"
|
|
aliases:
|
|
tags:
|
|
- cosc203
|
|
- lecture
|
|
sr-due: 2022-12-06
|
|
sr-interval: 22
|
|
sr-ease: 270
|
|
---
|
|
|
|
|
|
# TLS
|
|
- security protocol above transport layer.
|
|
- supported by most browsers
|
|
- prvides, confidentaility, integrity, authentication
|
|
- replaced SSL
|
|
|
|
- provides API that any application can use
|
|
- 
|
|
- QUIC and http3: moves transpor tlayer functions to app layer, on top of UDP
|
|
|
|
how
|
|
- handshake: use certificates, private keys to authenticate each other, exchange or create shared secret
|
|
- key derivation: use shared secret to derive set of keys
|
|
- data transfer: as a series of records, not just one time transactions
|
|
- connection closure: special message to close message
|
|
|
|
|
|
protocols
|
|
- handshake protocol
|
|
- changechipherspec protocol
|
|
- choose encryption algerithms
|
|
- alert Protocol
|
|
- terminate
|
|
- error reporting
|
|
- record protocol
|
|
- divide data to segments
|
|
- encrypt and authenticate and send
|
|
|
|
handshake
|
|
- 
|
|
|
|
cryptographic keys
|
|
- bad to use the same key for more than one crytographic algorithm (encryption and authentication)
|
|
- uses master secret
|
|
- 
|
|
|
|
record protocol
|
|
- encrypt and athenticate data
|
|
- 
|
|
- divide in to small segements, encrypt each one, MAC (message authentication code)
|
|
|
|
changeCipherSpec and alert
|
|
|
|
|
|
https and ssh
|
|
- https = http over tls
|
|
- ssh
|
|
- replacement for telnet
|
|
- similar to tls
|
|
- data encryption
|
|
- authentication
|
|
|
|
# IPSec
|
|
- IP layer security
|
|
- datagram level encryption, authentication, integrity
|
|
- both user traffic and control traffic
|
|
- two modes
|
|
- transport mode
|
|
- only payload not header encrypted, and authenticated
|
|
- tunnel mode
|
|
- entire datagram is encrypted
|
|
- encrypted datagram encapsulated in new datagram with new IP header, tunneled to destination (new IP different from first e.g., next router)
|
|
|
|
Authentication header (AH) protocol
|
|
- provides source authenticatio and data inegrity not confidentiality
|
|
|
|
encapsulation security protocol (ESP)
|
|
- provides source authentication, data integrity, and confidentiality
|
|
- used more than AH
|
|
- 
|
|
- ESP trailer: padding for block ciphers
|
|
- ESP header: SPI so recieving entity knows what to do
|
|
- sequence number, to thwart replay attacks
|
|
- MAC in ESP auth field created with shared secret key
|
|
- path
|
|
- at R1: appends ESP trailer, encrypts result using algorithm and key
|
|
- appends header to front
|
|
- created authentication MAC
|
|
- appends MAC forming payload
|
|
- creates new IP header, new IP header fields, addresses to tunnel endpoint
|
|
|
|
# firewall
|
|
- isolates orgs internal network from larger internet, allowiing some packets to pass, blocking others
|
|
|
|
three types
|
|
- stateless packet fiiltering
|
|
- filters packet by packet, decision to forward/drop based on
|
|
- source, dest IP
|
|
- TCP/UDP source, dest port
|
|
- ICMP type
|
|
- TCP SYN, ACK bits
|
|
- e.g., block incoming and outgoing datagrams with IP protocol field = 17 and with either source or dest port = 23
|
|
- ACL access control list:
|
|
- 
|
|
- stafeful
|
|
- track status of every TCP connection
|
|
- using SYN, FIN segments => determine if packets "make sense"
|
|
- timeout inactinve connections at firewall: no longer admit packets
|
|
- 
|
|
- more powerful, more computation
|
|
- application gateways
|
|
- filters on application data as well as header fields
|
|
- e.g., allow seletc internal users to telnet outside
|
|
- require all telnet users to go through gateway
|
|
- for auth'd users, gateway sets up telnet connection to dest host
|
|
- gateway relays data between
|
|
- router filter blocks all telnet connections not from gateway
|
|
|
|
limitaitons
|
|
- IP spoofing
|
|
- if multiple apps need special treatment, each has own app. gateway
|
|
- client software must know how to contact gateway
|
|
- e.g., must set IP of proxy in browser
|
|
- filters oftenuser all or nothing policy for UDP
|
|
- tradeoff: access with security
|
|
|
|
# IDS
|
|
- instrusion detection system
|
|
- deep packet inspection
|
|
- look at contents (e.g., check strings in packet against DB of known virus, attack strings)
|
|
- examine correlation among packets
|
|
- port scanning
|
|
- network mapping
|
|
- DoS attack
|
|
|
|
multiple IDSs: different types of checking at different locations |