VPNs.md

IPSec

• a TCP/IP #encryption protocol
• used by l2tp
• uses IKE for key exchange

IKE

• Internet Key Exchange
• method for secure key exchange when setting up a secure tunnel

PPP

• Point to point protocol
• #vpn protocol
• #port:

PPTP

• Point to point tunneling protocol
• #vpn protocol
• #port: 1723
• Encapsulates & encrypts PPP packets
• uses CHAP authentication, vulnerable to attack.

L2TP

• Layer 2 tunneling protocol
• #vpn protocol
• #port: 1701
• connection between two devices not on same network
• stronger than pptp
• not encrypted by default: paired with IPSEC

Secure Association (SA)

• establishing secure connections by keys or certificates

Authentication Header (AH)

• Header information of the packets used in IPSec
• provides authenticity & integrity

ESP

• Encapsulating Security Payload
• more secure than just AH
• encapsulates, encrypts, & authenticates content of the IPSec packets
• Tunnel mode & transport mode
  • tunnel - for outside connections, totally encrypted
  • transport - for internal networks, leaves headers visible