Modbus
Cellular
Gateway
Index
skipping
is
used
to
reserve
slots
for
new
function
insertion,
when
required.
243
The
security
gateway
for
Network
‐
A
has
the
IP
address
of
10.0.76.2
for
LAN
interface
and
203.95.80.22
for
WAN
interface.
It
serves
as
a
L2TP
server.
However,
Network
‐
B
is
in
the
mobile
office
and
the
subnet
of
its
Intranet
is
10.0.75.0/24.
The
security
gateway
for
Network
‐
B
has
the
IP
address
of
10.0.75.2
for
LAN
interface
and
118.18.81.33
for
WAN
interface.
It
serves
as
a
L2TP
client.
L2TP
server
provides
two
user
accounts,
User
‐
1
and
User
‐
2,
for
L2TP
clients
dialing
in.
Establish
a
L2TP
VPN
tunnel
by
starting
from
the
L2TP
client
site.
So
both
Intranets
of
10.0.75.0/24
and
10.0.76.0/24
can
securely
communicate
each
other.
Finally,
the
client
hosts
in
the
Intranet
of
Network
‐
B
at
mobile
office
can
access
the
server
or
database
resources
in
the
Intranet
of
Network
‐
A
at
HQ
in
a
secured
link.
L2TP
VPN
Client
Scenario
When
you
want
the
security
gateway
to
play
a
L2TP
client
role,
check
the
"Enable"
box
and
choose
"Client"
option
in
the
"L2TP
Configuration"
window.
And
make
its
related
configuration
in
following
sections.
L2TP
Client
Configuration
"L2TP
Client
Configuration"
window
can
let
you
enable
the
L2TP
client
function
by
checking
the
"Enable"
box.
L2TP
Client
List
&
Status
"L2TP
Client
List
&
Status"
window
shows
your
defined
L2TP
clients
and
their
tunnel
status.
Only
some
important
information
for
all
tunnels
are
shown
in
the
list
as
following
diagram.
Configuration
for
A
L2TP
Client
"Configuration
for
A
L2TP
Client"
window
let
you
specify
the
required
parameters
for
a
L2TP
VPN
client,
such
as
"L2TP
Client
Name",
"Interface",
"Operation
Mode",
"L2TP
over
IPSec",
"Remote
LNS
IP/FQDN",
"Remote
LNS
Port",
"User
Name",
"Password",
"Tunneling
Password",
"Default
Gateway/Remote
Subnet",
"Authentication
Protocol",
"MPPE
Encryption",
"NAT
before
Tunneling",
"LCP
Echo
Type",
"Service
Port",
and
tunnel
activation.
Please
be
noted
that
"Default
Gateway/Remote
Subnet"
configuration
item.
There
are
two
options,
"Default
Gateway"
and
"Remote
Subnet".
When
you
choose
"Remote
Subnet",
you
need
specify
one
more
setting:
the
remote
subnet.
It
is
for
the
Intranet
of
L2TP
VPN
server.
So,
at
L2TP
client
peer,
the
packets
whose
destination
is
in
the
dedicated
subnet
will
be
transferred
via
the
L2TP
VPN
