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Firewall. Matthew Prestifilippo, Bill Kazmierski, Pat Sparrow. Basics. Intended to stop unauthorized traffic from traveling from one network to another Between router and internal network setup. Basics.

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firewall
Firewall

Matthew Prestifilippo, Bill Kazmierski, Pat Sparrow

basics
Basics
  • Intended to stop unauthorized traffic from traveling from one network to another
  • Between router and internal network setup
basics1
Basics

All data arriving at or leaving the network passes through the firewall, where it can be accepted or denied.

A list of rules can be set, allowing the firewall to determine what types of data should not be allowed to pass through .

These rules can allow certain devices inside the network to have different privileges

filtering
Filtering
  • Packet Filters
    • This job is done in the transport and network layer
    • Looks at the packets to see if forbidden IP’s are trying to come in.
    • Not affective in the case of spoofing
  • Stateful Inspection
    • Use ACK and SYN packet for verification/correspondence
    • Keeps track of sessions
filtering1
Filtering
  • Application Proxies
    • Application level
    • Extra processing power needed, but more security provided
filtering2
Filtering
  • A firewall can filter packets based on the source or destination IP address
  • A firewall can filter packets based on the destination port
  • A firewall can filter packets based on the protocol (UDP, TCP, IP …)
interfaces
Interfaces
  • 3 basic interfaces:
    • 1. Inside – trusted network
    • 2. Outside – untrusted network
    • 3. DMZ – demilitarized zone
      • Web server
      • Why a DMZ?
slide8
NAT
  • Static
    • Permanent inside local -> inside global mapping
  • Dynamic
    • Pool of global addresses are defined. Machines that make a request to the outside are assigned accordingly.
slide9
NAT
  • Overloading (PAT)
    • When there are more nodes than there are global addresses available, use port space to map to extra machines
    • This means that one address can be used for multiple computers (hence the term overloading)
url filtering
URL Filtering
  • Need a N2H2 or a Websense server
  • Filtering process includes the PIX relying on the server to determine whether or not a website is allowed.
  • Could also use the access-list command
packet inspection
Packet Inspection
  • A Firewall must inspect every packet traveling in and out of a network
  • Too many rules can result in a bottleneck
  • Looking up domain names while logging can slow performance
  • Using VPN and other functions can slow the performance
pix 515e firewall
PIX 515e Firewall
  • 433 MHz Intel Celeron processor
  • 64 MB RAM
  • 16 MB onboard flash memory
  • 188 Mbps throughput
  • can handle more than 130,000 sessions
  • Recommended for small to medium-sized business networks
our setup
Our Setup
  • We reset the firewall with the inside IP address of 134.198.161.254 with a netmask of 255.255.248.0, which is the same as the inside address of the original network configuration
  • We set the outside IP address to 134.161.170.252, which is the same as the original network configuration.
  • The PIX515 has replaced the router.
  • By default, the firewall allows outgoing traffic to any IP address.
rules
Rules
  • Source and Destinations IPs
  • Source and Destination interface
  • Type of Packet
  • Default rule:

Source: 0.0.0.0 on inside interface

Destination: 0.0.0.0 on outside interface

Packet Type: IP

Action: Permit

our rules
Our Rules
  • Allow all traffic to enter the network

Source: 0.0.0.0 on the outside

Destination: 0.0.0.0 on the inside

Packet Type: IP

Action: Permit

  • Prevent hosts from accessing Playboy.com

Source: 216.163.137.3 on the outside

Destination: 0.0.0.0 on the inside

Packet Type: IP

Action: Deny

work with ids
Work With IDS
  • View IDS logs to find any bad IPS and add rules to prevent them from sending packets to the network