1. Remote Access
Lecture 2

2. Security Protocols IPSec L2TP - Layer 2 Tunneling Protocol
SSL – Secure Socket Layers
Kerberos
SSH – Secure Shell
RADIUS – Remote Authentication Dial-in Service

3. Encryption
Process of encoding data using a mathematical algorithm that makes it difficult for unauthorized users to read the data if they intercept it.
Encryption requires a key (math. Algorithm) to read the data.
Two types of encryption
Symmetric – same key is used to encrypt/decrypt
Asymmetric – two keys – public key encrypts the message; the private key decrypts.
Key – binary number made up of a large number of bits
56 bit encryption – 256
128 bit encryption – used online

4. IPSec LANs or WANs using TCP/IP only Encrypts data Provides
Verification – data is from intended source
Protection – an intermediary did not alter the message
Privacy – unreadable by others
Operates at the network layer
Security operates at the higher layers

5. PPTP Point to Point Tunneling Protocol Dial-up Provides secure tunnel
Other connectivity protocols like PPP can be used inside the tunnel
PPTP control connection – between client IP and server IP - created using TCP
Uses port 1723

6. L2F Cisco proprietary protocol
Permits tunneling over insecure networks

7. L2TP – Layer 2 Tunneling Combination of PPTP and L2F Two phase process
Authenticates computer
Authenticates user
Operates at Layer 2
Protocol independent
Will not work with NAT
Requires digital certificate
key attached to the message
Offers greater security than PPTP

8. SSL Used on the Internet – HTTPS (port 443) Three services
Server authentication
Client verifies server identity
Client authentication
Server verifies client identity
Encrypted Connection
Uses public key encryption

9. Kerberos Provides client/server applications w/authentication
Server and clients must prove identities to one another
Each communicating party is issued a “ticket” which is embedded in messages and used to identify the user
Open source

10. SSH - Secure Shell Secure replacement for Telnet
Entire session is encrypted
Provides interoperability between
LINUX
UNIX
Windows 9x/NT/200x
Macintosh
Freeware: PuTTY

11. ICA – Independent Computing Architecture
Allows clients to access and run applications on a server using the server’s resources. (dumb terminal)
Thin client – only a small piece of software is needed on the client system.
Platform independent
Example: Citrix

12. RADIUS – Remote Auth. Dial-in User Service
Client/server protocol
Consists of
Central server
Database
Authentication – using PAP or CHAP – identifies users
Authorization – gives users’ access
Accounting – tracks user accesses, failed attempts, time, etc.
One or more dial-in servers

13. RADIUS Central server has database to determine user
RAS 1
RAS 2
Client dials in; could hit remote access server 1 or 2

14. Types of Access Dial-up VPN VPN Sessions Modem to modem Authentication
All O/S support
VPN
Provides low-cost (as compared to leased line) secure network connection
Point to point dedicated link over a public IP network
Creates a connection between two computers
Uses PPP
VPN Sessions
VPN client initiates connection to server
Server authenticates VPN clients
Protocols – PPTP or L2TP