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Email Security IPsec 1 * Essential Network Security Book Slides. IT352 | Network Security |Najwa AlGhamdi 1
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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
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IP Security general IP Security mechanisms provides – authentication – confidentiality – key management applicable to use over LANs, across public & private WANs, & for the Internet
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IP Security Uses
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Benefits of IPSec 1.IPsec in a firewall/router provides strong security to all traffic crossing the perimeter 2.IPsec in a firewall/router is resistant to bypass 3.is below transport layer, hence transparent to applications 4.can be transparent to end users 5.can provide security for individual users
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IPSec Services 1.Access control 2.Connectionless integrity 3.Data origin authentication 4.Confidentiality (encryption) Two protocols are used to provide security: 1.an authentication protocol designated by the header of the protocol, Authentication Header (AH); 2. 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.
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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.
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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
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IPSec Modes of Operation Transport Mode: protect the upper layer protocols IP Header TCP Header Dat a Original IP Datagram IP Header TCP Header IPSec Header Dat a Transport Mode protected packet Tunnel Mode: protect the entire IP payload Tunnel Mode protected packet New IP Header TCP Header IPSec Header Dat a Original IP Header protected
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Tunnel Mode Host-to-Network, Network-to- Network Protecte d Data IPSec IP Layer SG Inter net Transpo rt Layer Applicat ion Layer IP Layer Host B Protecte d Data IPSec IP Layer SG Transpo rt Layer Applicat ion Layer IP Layer Host A SG = Security Gateway
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Transport Mode Transport Layer Application Layer Host-to-Host Transport Layer Application Layer IP Layer Data Link Layer IPSec Host B IP Layer Data Link Layer IPSec Host A
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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
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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
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IP Traffic Processing IT352 | Network Security |Najwa AlGhamdi 14
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IP Traffic Processing IT352 | Network Security |Najwa AlGhamdi 15
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