Case study: build an e-commerce

Componenents

• Web server
• Replicated web server, for load-sharing and reliability
• System admins
• Development mahinces
• Developer access
• Console servers
• Environmental control systems - air conditioning, power, backup generators..
• Backup servers
• DNS servers
• ... (Many more!)

How to connect pieces?

• Which pieces should be separated?
• E.g A billing system: 4 different database..

Why so complex?

• Availability - primarily against ordinary fialtures.
• Everything is replicated: routers, links, Ethernets, servers..

Inverse proxy

• Inverse proxies are effectively firewalls: only ports 80 (http) and 443 (https).
• Database servers are not accessible from outside; when a request comes in, you must go through web server first.

What are the security goals:

• C.I.A
• Different sources have different goals.
  • Database: availability
  • Web server: confidentiality..

Protect web servers

• Within web servers, isolate different parts.
• Separate UIDs on the Web Server
  • Least Priviledge: login CGI script runs as different user than browsing CGIs.

Protect database machines

• If the database is tampered with, VERY BAD THINGS can happen.
• How can database machines attacked?
  • Hacking attack: web server falls $\rightarrow$ database machine (issue arbitrary SQL statements to database).
  • SQL injection attack: bypass web server and directly affects database machine.
• Protection: mandate the customer log in to the database.
  • All customer-type operation must be accompanied by customer-type authentication.

Protect inventory database

• Use a separate database and database machine for orders.
• Protecting information: credit card numbers not readable by web server.

Danger points

• How are these devices managed?