Modbus
Cellular
Gateway
Index
skipping
is
used
to
reserve
slots
for
new
function
insertion,
when
required.
227
5.5.5
PPTP
The
Point
‐
to
‐
Point
Tunneling
Protocol
(PPTP)
is
a
method
for
implementing
virtual
private
networks.
PPTP
uses
a
control
channel
over
TCP
and
a
GRE
tunnel
operating
to
encapsulate
PPP
packets.
The
PPTP
specification
does
not
describe
encryption
or
authentication
features
and
relies
on
the
Point
‐
to
‐
Point
Protocol
being
tunneled
to
implement
security
functionality.
However,
the
most
common
PPTP
implementation
shipping
with
the
Microsoft
Windows
product
families
implements
various
levels
of
authentication
and
encryption
natively
as
standard
features
of
the
Windows
PPTP
stack.
The
intended
use
of
this
protocol
is
to
provide
security
levels
and
remote
access
levels
comparable
with
typical
VPN
products.
Deploy
a
security
gateway
for
local
office
and
establish
a
virtual
private
network
with
the
remote
gateway
of
another
office
by
using
PPTP
tunneling.
So,
all
client
hosts
behind
local
security
gateway
can
make
data
communication
with
others
behind
remote
gateway.
Or
when
you
are
a
mobile
user
with
a
notebook
or
carrying
along
a
security
gateway
and
you
want
to
access
the
servers
and
database
in
company
headquarters
(HQ).
In
addition,
the
security
gateway
in
HQ
supports
the
PPTP
VPN
server
function.
So
you
can
dial
in
the
HQ
gateway
and
access
the
HQ
resources
by
establishing
a
PPTP
VPN
tunnel.
It
is
a
virtual
private
network
between
your
device
and
HQ
gateway
for
your
resource
accessing.
In
"PPTP"
page,
there
is
the
"Configuration"
window
to
enable
the
PPTP
VPN
function.
Moreover,
the
security
gateway
can
play
either
"PPTP
Server"
role
or
"PPTP
Client"
role
or
they
both
at
the
same
