<s>
Split	B-Application
tunneling	I-Application
is	O
a	O
computer	B-Architecture
networking	I-Architecture
concept	O
which	O
allows	O
a	O
user	O
to	O
access	O
dissimilar	O
security	B-Protocol
domains	I-Protocol
like	O
a	O
public	O
network	O
(	O
e.g.	O
,	O
the	O
Internet	O
)	O
and	O
a	O
local	B-General_Concept
area	I-General_Concept
network	I-General_Concept
or	O
wide	O
area	O
network	O
at	O
the	O
same	O
time	O
,	O
using	O
the	O
same	O
or	O
different	O
network	O
connections	O
.	O
</s>
<s>
This	O
connection	O
state	O
is	O
usually	O
facilitated	O
through	O
the	O
simultaneous	O
use	O
of	O
a	O
LAN	B-General_Concept
network	I-General_Concept
interface	O
controller	O
(	O
NIC	O
)	O
,	O
radio	O
NIC	O
,	O
Wireless	B-Architecture
LAN	I-Architecture
(	O
WLAN	B-Architecture
)	O
NIC	O
,	O
and	O
VPN	B-Application
client	I-Application
software	O
application	O
without	O
the	O
benefit	O
of	O
an	O
access	O
control	O
.	O
</s>
<s>
For	O
example	O
,	O
suppose	O
a	O
user	O
utilizes	O
a	O
remote	B-Protocol
access	I-Protocol
VPN	B-Application
software	O
client	O
connecting	O
to	O
a	O
campus	B-General_Concept
network	I-General_Concept
using	O
a	O
hotel	O
wireless	B-General_Concept
network	I-General_Concept
.	O
</s>
<s>
The	O
user	O
with	O
split	B-Application
tunneling	I-Application
enabled	O
is	O
able	O
to	O
connect	O
to	O
file	B-Application
servers	I-Application
,	O
database	B-Application
servers	I-Application
,	O
mail	B-Protocol
servers	I-Protocol
and	O
other	O
servers	O
on	O
the	O
corporate	B-General_Concept
network	I-General_Concept
through	O
the	O
VPN	B-Application
connection	O
.	O
</s>
<s>
When	O
the	O
user	O
connects	O
to	O
Internet	O
resources	O
(	O
websites	O
,	O
FTP	B-Protocol
sites	I-Protocol
,	O
etc	O
.	O
</s>
<s>
)	O
,	O
the	O
connection	O
request	O
goes	O
directly	O
out	O
the	O
gateway	B-Application
provided	O
by	O
the	O
hotel	O
network	O
.	O
</s>
<s>
However	O
,	O
not	O
every	O
VPN	B-Application
allows	O
split	B-Application
tunneling	I-Application
.	O
</s>
<s>
Some	O
VPNs	B-Application
with	O
split	B-Application
tunneling	I-Application
include	O
Private	B-Application
Internet	I-Application
Access	I-Application
(	O
PIA	O
)	O
,	O
ExpressVPN	B-Application
,	O
and	O
Surfshark	B-Application
.	O
</s>
<s>
Split	B-Application
tunneling	I-Application
is	O
sometimes	O
categorized	O
based	O
on	O
how	O
it	O
is	O
configured	O
.	O
</s>
<s>
A	O
split	B-Application
tunnel	I-Application
configured	O
to	O
only	O
tunnel	O
traffic	O
destined	O
to	O
a	O
specific	O
set	O
of	O
destinations	O
is	O
called	O
a	O
split-include	O
tunnel	O
.	O
</s>
<s>
One	O
advantage	O
of	O
using	O
split	B-Application
tunneling	I-Application
is	O
that	O
it	O
alleviates	O
bottlenecks	B-Protocol
and	O
conserves	O
bandwidth	O
as	O
Internet	O
traffic	O
does	O
not	O
have	O
to	O
pass	O
through	O
the	O
VPN	B-Application
server	I-Application
.	O
</s>
<s>
Split	B-Application
tunneling	I-Application
prevents	O
the	O
user	O
from	O
having	O
to	O
continually	O
connect	O
and	O
disconnect	O
.	O
</s>
<s>
A	O
disadvantage	O
is	O
that	O
when	O
split	B-Application
tunneling	I-Application
is	O
enabled	O
,	O
users	O
bypass	O
gateway	B-Application
level	O
security	O
that	O
might	O
be	O
in	O
place	O
within	O
the	O
company	O
infrastructure	O
.	O
</s>
<s>
For	O
example	O
,	O
if	O
web	O
or	O
content	B-Protocol
filtering	I-Protocol
is	O
in	O
place	O
,	O
this	O
is	O
something	O
usually	O
controlled	O
at	O
a	O
gateway	B-Application
level	O
,	O
not	O
the	O
client	O
PC	O
.	O
</s>
<s>
ISPs	O
that	O
implement	O
DNS	B-Protocol
hijacking	I-Protocol
break	O
name	O
resolution	O
of	O
private	O
addresses	O
with	O
a	O
split	B-Application
tunnel	I-Application
.	O
</s>
<s>
A	O
variant	O
of	O
this	O
split	B-Application
tunneling	I-Application
is	O
called	O
"	O
inverse	O
"	O
split	B-Application
tunneling	I-Application
.	O
</s>
<s>
By	O
default	O
all	O
datagrams	B-Protocol
enter	O
the	O
tunnel	O
except	O
those	O
destination	O
IPs	O
explicitly	O
allowed	O
by	O
VPN	B-Application
gateway	B-Application
.	O
</s>
<s>
The	O
criteria	O
for	O
allowing	O
datagrams	B-Protocol
to	O
exit	O
the	O
local	B-General_Concept
network	I-General_Concept
interface	O
(	O
outside	O
the	O
tunnel	O
)	O
may	O
vary	O
from	O
vendor	O
to	O
vendor	O
(	O
i.e.	O
</s>
<s>
This	O
keeps	O
control	O
of	O
network	B-Application
gateways	I-Application
to	O
a	O
centralized	O
policy	O
device	O
such	O
as	O
the	O
VPN	B-Application
terminator	O
.	O
</s>
<s>
This	O
can	O
be	O
augmented	O
by	O
endpoint	O
policy	O
enforcement	O
technologies	O
such	O
as	O
an	O
interface	O
firewall	B-Application
on	O
the	O
endpoint	O
device	O
's	O
network	O
interface	O
driver	O
,	O
group	O
policy	O
object	O
or	O
anti-malware	B-Application
agent	O
.	O
</s>
<s>
A	O
form	O
of	O
split-tunneling	O
that	O
derives	O
the	O
IP	B-Protocol
addresses	I-Protocol
to	O
include/exclude	O
at	O
runtime-based	O
on	O
a	O
list	O
of	O
hostname	B-Protocol
rules/policies	O
.	O
</s>
<s>
Internal	O
IPv6	B-Protocol
content	O
can	O
be	O
hosted	O
and	O
presented	O
to	O
sites	O
via	O
a	O
unique	B-Protocol
local	I-Protocol
address	I-Protocol
range	O
at	O
the	O
VPN	B-Application
level	O
,	O
while	O
external	O
IPv4	B-Protocol
&	O
IPv6	B-Protocol
content	O
can	O
be	O
accessed	O
via	O
site	O
routers	O
.	O
</s>
