SystemsSec 2018W Lecture 5

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Lecture 5 Audio


- Basic structure of the internet

  • client => net => server
  • basic client server model
  • processes on client and server talk to each other
  • network firewall sits between net and server, protects the network from malicious incoming traffic
  • host firewall sits between net and server, sits in front of server
  • each process has a unique port number
  • IP address identifies hosts

- IP addresses are very easy to spoof - Initially, servers would talk to any client, very risky - Finger daemon lists for finger requests

  • process that can find out anyone's personal info (eg. name, phone number, etc.)
  • eg: finger
  • outputs a "plan" file with user's personal info

- chargen = character generator - localhost:631 = url for CUPS

  • web-based printer management console for unix systems
  • config file has basic access control (ie. IP address restriction)
  • not openly available, secure for single host, not so good for multiple hosts (ie. network)

- security issues?

  • different config files for different OS, tedious to setup
  • ideally, we want a uniform way of combining policy

- TCP wrappers "libwrap"

  • came before host based, widespread firewall support

- what is a firewall?

  • 2 types: host and network, differs by who enforces the rules

- what is a vpn?

  • virtual private network
  • can be problematic, misused if used to download media onto your machine while connected to a company network
  • viruses can enter the network this way

- to increase network security, turn off unnecessary services that don't need to talk over the network like the finger daemon - outgoing traffic is safe but incoming traffic may not be - ntpd = network time protocol daemon - modern architecture uses VMs and containers like Docker

  • Processes in Docker separated into groups
  • 1 firewall per group