Tunnel IPSEC
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SER
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T
UNNEL
IPSEC
I
NTRODUCTION
IPSec is the abbreviation of IP Security and it is an open standard that exchange data in confidential
and encrypted mode, for layer 3 connections. IPSec make secure connection, by adding
cryptography and authentication to the IP packets.
The fact that protection is implemented on layer 3 of the OSI stack, makes this protocol transparent
to the application level, which continue to work with no needs of any software adjustment.
This chapter provides basic guidelines about the configuration of IPSec module, while a thorough
understanding of this protocol is beyond the scope of this manual.
B
UILDING IPSEC TUNNEL
S
The VPN IPSec configuration system allows to distinguish the configuration parameter related to
Phase I from those characteristics of Phase II. In this way, listings are much more synthetic and
more comprehensible.
For example, to configure the parameters referred to Phase I of a VPN IPSec connection in main
mode, the following commands are to be used:
set ipsec phase1 MAIN exchange-mode main
set ipsec phase1 MAIN local-end eth0
set ipsec phase1 MAIN remote-end 10.10.100.39
set ipsec phase1 MAIN encryption-algorithm 3des
set ipsec phase1 MAIN hash-algorithm sha1
set ipsec phase1 MAIN dh-group 2
set ipsec phase1 MAIN authentication-method pre_shared_key
The above parameters are the expression of:
the VPN IPSec mode is main
the local interface from which IPSec will start the connection (the parameter
local-end
accept as argument either the router interface or an IP address on the same router)
the IP address of the VPN terminator
the encryption algorithm
the hash algorithm
the Diffie-Hellman group