Modbus
Cellular
Gateway
Index
skipping
is
used
to
reserve
slots
for
new
function
insertion,
when
required.
207
5.5.3
IPSec
Internet
Protocol
Security
(IPSec)
is
a
protocol
suite
for
securing
Internet
Protocol
(IP)
communications
by
authenticating
and
encrypting
each
IP
packet
of
a
communication
session.
IPSec
includes
protocols
for
establishing
mutual
authentication
between
agents
at
the
beginning
of
the
session
and
negotiation
of
cryptographic
keys
to
be
used
during
the
session.
An
IPSec
VPN
tunnel
is
established
between
IPSec
client
and
server.
Sometimes,
we
call
the
IPSec
VPN
client
as
the
initiator
and
the
IPSec
VPN
server
as
the
responder.
There
are
two
phases
to
negotiate
between
the
initiator
and
responder
during
tunnel
establishment,
IKE
phase
and
IPSec
phase.
At
IKE
phase,
IKE
authenticates
IPSec
peers
and
negotiates
IKE
SAs
(Security
Association)
to
set
up
a
secure
channel
for
negotiating
IPSec
SAs
in
phase
2.
At
IPSec
phase,
IKE
negotiates
IPSec
SA
parameters
and
sets
up
matching
IPSec
SAs
in
the
peers.
After
these
both
phases,
data
is
transferred
between
IPSec
peers
based
on
the
IPSec
parameters
and
keys
stored
in
the
SA
database.
In
"IPSec"
page,
there
is
the
"Configuration"
window
to
enable
the
IPSec
for
VPN
function
to
activate
network
neighborhood
between
the
Intranets
of
local
and
remote
peers.
It
enables
the
VPN
tunnels
even
the
gateway
is
under
a
NAT
router
and
specify
the
maximum
concurrent
IPSec
tunnels.
In
addition,
there
is
one
more
"Tunnel
List
&
Status"
window
lists
the
created
IPSec
VPN
tunnels
and
their
connection
status.
To
add
and
create
a
new
tunnel,
click
on
the
"Add"
button.
There
are
some
configuration
windows
for
you
to
setup.
They
are
"Tunnel
Configuration",
"Local
&
Remote
Configuration",
"Authentication",
"IKE
Phase",
"IKE
Proposal
Definition",
"IPSec
Phase",
and
"IPSec
Proposal
Definition"
windows.
