User guide

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An arbitrary 32-bit number called a Security Parameters Index

(SPI), as well as the destination host’s address and the IPSEC

protocol identiﬁer, identify each SA. An SPI is assigned to an SA

when the SA is negotiated. The SA can be referred to by using

an SPI in AH and ESP transformations. SA is unidirectional. SAs

are commonly setup as bundles, because typically two SAs are

required for communications. SA management is always done

on bundles (setup, delete, relay).

serial communication. Method of data transmission in which

data bits are transmitted sequentially over a communication

channel

SHA-1. An implementation of the U.S. Government Secure

Hash Algorithm; a 160-bit authentication algorithm.

Soft MBytes. Setting the Soft MBytes parameter forces the

renegotiation of the IPSec Security Associations (SAs) at the

conﬁgured Soft MByte value. The value can be conﬁgured

between

1 and 1,000,000 MB

and refers to data trafﬁc passed.

If this value is not achieved, the Hard MBytes parameter is

enforced.

Soft Seconds. Setting the Soft Seconds parameter forces the

renegotiation of the IPSec Security Associations (SAs) at the

conﬁgured Soft Seconds value. The value can be conﬁgured

between 60 and 1,000,000 seconds.

SPI . The Security Parameter Index is an identiﬁer for the

encryption and authentication algorithm and key. The SPI indi-

cates to the remote ﬁrewall the algorithm and key being used to

encrypt and authenticate a packet. It should be a unique num-

ber greater than 255.