Email Security

1. Email Security IPsec 1 * Essential Network Security Book Slides. IT352 | Network Security |Najwa AlGhamdi

2. IP Security • have a range of application specific security mechanisms • eg. S/MIME, PGP, Kerberos, SSL/HTTPS • however there are security concerns that cut across protocol layers • would like security implemented by the network for all applications

3. IP Security • general IP Security mechanisms • provides • authentication • confidentiality • key management • applicable to use over LANs, across public & private WANs, & for the Internet

4. IP Security Uses

5. Benefits of IPSec • IPsec in a firewall/router provides strong security to all traffic crossing the perimeter • IPsec in a firewall/router is resistant to bypass • is below transport layer, hence transparent to applications • can be transparent to end users • can provide security for individual users

6. IPSec Services • Access control • Connectionless integrity • Data origin authentication • Confidentiality (encryption) Two protocols are used to provide security: • an authentication protocol designated by the header of the protocol, Authentication Header (AH); • and a combined encryption/authentication protocol designated by the format of the packet for that protocol, Encapsulating Security Payload (ESP) • Both AH & ESP support two modes of use : Transport and Tunnel mode.

7. Transport and Tunnel Modes • Transport Mode • to encrypt & optionally authenticate IP data (payload) . • When AH is used : IP payload and selected portion of the header will be authenticated. • When ESP is used : IP payload wil be encrypted. • When ESP with authentication is used : IP payload will be encrypted and authenticated.

8. Transport and Tunnel Modes • Tunnel Mode • encrypts entire IP packet • add new header for next hop. • When AH is used : authenticate the entire inner header + inner payload + a selected portion of the outer header. • When ESP is used : entire inner IP packet will be encrypted. • When ESP with authentication is used : entire inner IP packet will be encrypted and authenticated

9. IPSec Modes of Operation • Transport Mode: protect the upper layer protocols IP Header TCP Header Data Original IP Datagram Transport Mode protected packet IP Header IPSec Header TCP Header Data protected • Tunnel Mode: protect the entire IP payload New IP Header IPSec Header Original IP Header TCP Header Data Tunnel Mode protected packet protected

10. Tunnel Mode • Host-to-Network, Network-to-Network Application Layer Protected Data Protected Data Application Layer Transport Layer Transport Layer Internet IP Layer IP Layer IPSec IPSec Host A Host B IP Layer IP Layer SG SG SG = Security Gateway

11. Transport Mode • Host-to-Host Application Layer Application Layer Transport Layer Transport Layer IPSec IPSec IP Layer IP Layer Data Link Layer Data Link Layer Host A Host B

12. Security Associations • a one-way relationship between sender & receiver that affords security for traffic flow • defined by 3 parameters: • Security Parameters Index (SPI) • IP Destination Address • Security Protocol Identifier • have a database of Security Associations

13. Security Policy Database • relates IP traffic to specific SAs • match subset of IP traffic to relevant SA • use selectors to filter outgoing traffic to map • based on: local & remote IP addresses, next layer protocol, name, local & remote ports

14. IP Traffic Processing IT352 | Network Security |Najwa AlGhamdi

15. IP Traffic Processing IT352 | Network Security |Najwa AlGhamdi