1. What are they and what do they (not) do?
Firewalls
What are they and what do they (not) do?

2. Firewalls What is a firewall?
A firewall is any mechanism that acts to restrict access to a network according to a set of defined rules.
Function as “front doors” to a network.

3. Firewalls How do they work?
By inspecting traffic that travels across/through them according to the policy that’s been set.

4. Firewalls How are they set up?
Act as a go-between for any two given networks
Have Rules been met?
Yes? You can go.
No, you can’t.
The Internet
Firewall
Your Network

5. Firewalls Two main types Steps have been taken to create hybrids
Routing based filters
From where did you come?
Where are you going?
Don’t care what you do once you get there.
Content based filters
What are you trying to do?
Not as common as Routing based because it’s harder to implement successfully
Steps have been taken to create hybrids

6. Firewalls Two ways to approach the rule sets:
Allow all except what is defined as unwanted
Place roadblocks/watch gates along a wide open road.
Deny all except what is defined as wanted
Build a wall and carve paths for everyone you like.

7. Firewalls
Problems:
Firewalls as filters can be considered for most part to be infallible... but as a security measure? They can only enforce rules (generally static)
The Internet
Firewall
Your Network

8. Your trusted friends who aren’t security aware
Firewalls
“Crunchy on the outside, but soft and chewy on the inside.”
Step 1
Your hacker
Step 2
The Internet
Your firewall
Your trusted friends who aren’t security aware
Your network

9. Firewalls Conclusions
People don’t just put up a thick front door for their sensitive belongings, you shouldn’t for your network either.
Firewalls are an effective start to securing a network. Not a finish.
Care must be taken to construct an appropriate set of rules that will enforce your policy.