Computer Networks · free preview
Security Systems in Practice
The primitives and protocols of the previous lessons ship in a handful of working systems, PGP wrapping email in a web of trust, SSH replacing the password-in-the-clear remote login with strong authentication and session encryption plus port forwarding, TLS inserting a layer between applications and TCP that negotiates cipher suites in a handshake, authenticates the server by certificate, and derives session keys, which is what puts the lock icon beside the web's addresses, IPsec pushing security down to the IP layer with authentication headers and encapsulating security payloads in transport or tunnel mode, and firewalls enforcing the perimeter, filtering packets by policy between an inside and an outside, a complement to cryptography rather than a substitute.
1. Securing the Applications We Had
Securing the Applications We Had
2. The Handshake the Web Runs On
The Handshake the Web Runs On
3. Security at the IP Layer
Security at the IP Layer
4. The Perimeter and Its Limits
The Perimeter and Its Limits
5. The borrowed tunnel
What does SSH port forwarding provide, and why does it matter?
6. What the handshake buys
Which of these does the TLS handshake accomplish?
7. Why the server needs a certificate
Why does TLS authenticate the server with a certificate rather than a shared secret?
8. Headers and payloads
How do IPsec's two security protocols, the authentication header and the encapsulating security payload, differ in what they protect?
9. Tunnel mode's purpose
What does IPsec tunnel mode enable that transport mode does not?
10. The bypass problem
What is a firewall's structural weakness?
11. The web's layer
TLS inserts its security between the application and which transport protocol?
12. The remembered key
SSH clients authenticate servers by remembering what from the first connection?
13. The screened zone
What is the name of the screened network zone where a site places its exposed services between the outside and the soft interior?
14. The per-direction state
What does IPsec call the agreed keys, algorithms, and parameters protecting one direction of a conversation?
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