T
E
L
KO
MNIK
A
, V
ol
.
1
7
,
No.
6
,
Dec
e
mb
er
201
9
, p
p.
31
68
~
31
74
IS
S
N: 1
69
3
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93
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accr
ed
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F
irst
Gr
ad
e b
y K
em
en
r
istekdikti,
Decr
ee
No: 2
1/E/
K
P
T
/20
18
DOI:
10.12928/TE
LK
OM
N
IK
A
.v
1
7
i
6
.
13119
◼
31
68
Rec
ei
v
ed
May
14
,
20
1
9
; R
ev
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s
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J
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, 2
01
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; A
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th
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Key
w
ords
:
c
e
n
tra
l
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z
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d
SDN c
o
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tro
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l
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r,
d
i
s
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b
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t
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d
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tr
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l
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r
,
n
e
two
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k
s
e
c
u
r
i
ty
,
SDN
c
o
n
tro
l
l
e
r s
e
c
u
ri
t
y
,
s
o
ft
war
e
d
e
f
i
n
e
d
n
e
two
rk
Copy
righ
t
©
2
0
1
9
Uni
v
e
rsi
t
a
s
Ahm
a
d
D
a
hl
a
n.
All
rig
ht
s
r
e
s
e
rve
d
.
1.
Int
r
o
d
u
ctio
n
A
s
oft
w
are
de
fi
n
ed
ne
tw
ork
i
s
ne
twork
th
at
c
an
be
progr
am
me
d
.
T
hi
s
i
m
pl
i
es
tha
t,
the
eq
ui
pm
e
nt
i
n
tr
ad
i
ti
on
a
l
ne
tw
ork
s
uc
h
as
,
r
ou
ters
or
s
wi
tc
he
s
c
an
be
r
e
pl
ac
e
d
by
s
oft
war
e
progr
am
s
.
A
nd
s
uc
h
d
ev
i
c
es
c
an
be
c
o
ntro
l
l
e
d
by
a
s
oft
war
e
progr
a
m
t
ha
t
i
s
n
ot
e
mb
e
dd
e
d
i
n
the
ha
r
dware
i
ts
el
f.
F
or
ex
am
p
l
e,
i
n
th
e
tr
ad
i
ti
on
a
l
n
et
wor
k
,
a
l
i
nk
ba
n
dwi
dth
on
E
the
r
ne
t
s
wi
tc
h
i
s
c
on
f
i
gu
r
ed
on
the
s
wi
t
c
h
i
ts
e
l
f,
bu
t
i
n
s
o
ftware
de
f
i
n
ed
ne
tw
ork
,
th
i
s
c
a
n
b
e
d
on
e
o
n
the
O
p
en
F
l
ow c
on
tr
ol
l
er [1
]
.
A
s
the
nu
mb
er
of
de
v
i
c
es
c
on
ne
c
ted
t
o
the
n
et
wor
k
i
nc
r
ea
s
e
da
y
by
d
ay
an
d
the
c
ap
a
bi
l
i
ty
of
the
r
o
uti
ng
tab
l
e
i
s
l
i
mi
t
ed
,
a
tr
a
di
t
i
on
al
I
P
ne
t
wor
k
be
c
o
me
i
nc
r
ea
s
i
n
gl
y
di
ff
i
c
ul
t
to
m
an
a
ge
th
e
de
v
i
c
es
’
i
n
a
ne
t
wor
k
a
nd
c
on
fi
gu
r
a
ti
o
n
err
ors
ha
v
e
b
ec
o
me
s
c
om
mo
n
probl
em
s
[
2
-
5].
T
h
e
a
dm
i
ni
s
tr
ato
r
ha
s
to
i
s
s
ue
us
u
al
l
y
a
v
en
do
r
s
pe
c
i
fi
c
c
o
mm
a
nd
s
to
s
et
po
l
i
c
i
es
,
r
o
uti
ng
i
nfo
r
ma
t
i
on
an
d
ma
ny
n
etwo
r
k
p
aram
e
ters
r
eq
ui
r
e
d
for
t
he
ne
tw
ork
i
ng
d
ev
i
c
e
to
fun
c
ti
on
a
nd
op
era
te
s
m
oo
t
hl
y
.
T
he
c
om
p
l
ex
i
ty
of
d
ev
i
c
e
s
ma
na
g
em
e
nt
ha
d
the
r
e
fore,
mo
t
i
v
ate
d
the
r
es
e
a
r
c
he
r
s
to
thi
nk
ab
ou
t
a
ne
w
ne
t
wor
k
i
ng
p
arad
i
g
m,
wh
i
c
h
i
s
the
s
oft
war
e
de
f
i
ne
d
ne
twork
.
Unl
i
k
e,
the
tr
ad
i
t
i
on
al
n
etwo
r
k
,
th
e
ne
w
ap
proac
h
i
s
ba
s
ed
o
n
de
c
ou
pl
ed
ha
r
dware,
c
o
ntrol
pro
gram,
whi
c
h
i
s
c
al
l
ed
th
e
S
D
N
c
o
ntrol
l
er.
T
he
de
c
ou
pl
i
n
g
of
the
s
oft
w
are
fr
om
t
he
h
ard
war
e
s
i
m
pl
i
fi
es
ne
twork
m
an
a
ge
me
nt
an
d i
s
c
os
t e
ffe
c
ti
v
e
whe
n
c
om
p
ared to
th
e
trad
i
ti
on
a
l
a
pp
r
o
ac
h.
T
he
s
oft
war
e
de
f
i
ne
d
ne
t
wor
k
i
s
a
ne
twork
arc
h
i
te
c
ture
wh
ere
t
he
c
o
ntrol
l
o
gi
c
a
nd
forwar
di
ng
fu
nc
ti
o
na
l
i
t
i
es
are
s
ep
arat
ed
i
nto
d
i
ffe
r
e
nt
l
ay
ers
,
the
c
o
ntrol
l
a
bl
e
progr
am
a
nd
the
p
hy
s
i
c
al
i
nfras
tr
uc
tur
e l
ay
ers
. The k
ey
pri
nc
i
p
l
es
of
s
oft
war
e
de
f
i
ne
d n
etwo
r
k
a
r
e [
6]:
-
Cont
r
o
l
p
l
an
e
-
de
al
s
w
i
th
I
P
r
ou
ti
n
g a
nd
f
orw
ard
i
ng
de
c
i
s
i
on
s
-
Data
pl
a
ne
-
r
es
po
ns
i
b
l
e f
or
en
d t
o e
nd
d
el
i
v
ery
of
d
ata
i
n t
he
n
etwo
r
k
.
-
P
r
og
r
a
mm
a
bl
e n
e
twork
c
en
tr
al
l
y
ma
n
ag
e
d
-
the
m
a
na
g
em
en
t fu
nc
ti
o
na
l
i
t
i
es
are
c
e
ntral
i
z
ed
.
-
O
pe
n
i
nte
r
f
ac
es
be
t
wee
n t
h
e d
ev
i
c
e
i
n
th
e
c
on
tr
o
l
p
l
an
e a
n
d t
h
e d
a
ta
p
l
a
ne
.
In
s
oft
w
are
d
efi
ne
d
ne
t
wor
k
,
the
c
o
ntro
l
p
l
an
e,
ma
n
ag
es
the
en
t
i
r
e
de
v
i
c
e
i
n
the
ne
tw
ork
;
th
erefore,
i
t
i
s
the
c
or
e
e
l
e
me
nt
of
th
e
ne
tw
ork
.
T
he
r
ou
t
i
ng
po
l
i
c
i
es
or
th
e
f
l
ow
Evaluation Warning : The document was created with Spire.PDF for Python.
T
E
L
KO
MNIK
A
IS
S
N: 1
69
3
-
6
93
0
◼
A
r
ev
i
e
w on
s
oft
war
e d
e
fi
n
ed
n
etwo
r
k
s
ec
urit
y
r
i
s
k
s
a
nd
c
ha
l
l
en
g
es
(
T
s
eh
ay
A
d
ma
s
s
u A
s
s
eg
i
e
)
3169
r
ul
es
,
s
ec
uri
ty
po
l
i
c
y
a
nd
ev
ery
ma
n
ag
e
me
n
t
as
p
ec
t
of
t
he
ne
tw
ork
are
c
en
tr
al
i
z
e
d
t
hroug
h
the
us
e
of
S
DN
c
on
tr
o
l
l
er.
W
h
i
l
e
the
us
e
of
t
he
c
en
tr
al
i
z
e
d
S
DN
c
o
ntrol
l
er
i
s
an
op
p
ortun
i
ty
to
s
i
mp
l
i
fy
th
e
ne
tw
ork
ma
n
ag
em
en
t
an
d
ad
mi
n
i
s
tr
at
i
on
,
i
t
ha
s
al
s
o
i
ntrod
uc
ed
n
ew
s
ec
urit
y
i
s
s
ue
s
be
c
au
s
e
of
the
c
e
ntral
i
z
e
d
S
DN
c
on
tr
ol
l
er
arc
hi
tec
t
ure
[7]
.
O
n
e
ac
h
l
ay
ers
of
the
s
oft
w
are
de
fi
ne
d
ne
t
wor
k
,
th
ere
are
di
ff
erent
s
ec
urit
y
r
i
s
k
s
,
a
nd
th
e
foc
us
of
th
i
s
p
ap
er
i
s
on
s
ec
ur
i
ty
i
s
s
ue
s
an
d
r
i
s
k
s
on
th
e c
on
tr
ol
p
l
an
e.
2.
Rela
t
ed
W
o
r
ks
T
hi
s
s
ec
ti
on
f
oc
us
es
o
n
s
om
e
of
the
r
es
ea
r
c
h
w
ork
s
r
el
at
ed
t
o
t
he
i
m
pl
em
e
n
tat
i
on
,
c
ha
l
l
en
g
es
a
nd
fut
ur
e
d
i
r
ec
ti
on
s
of
the
s
oft
w
are
de
fi
ne
d
n
etwo
r
k
pr
i
m
aril
y
,
the
s
ec
urit
y
c
ha
l
l
en
g
es
at
c
on
tr
ol
l
ay
er.
A
l
tho
ug
h,
the
r
e
are
s
om
e
w
ork
s
r
el
ate
d
to
t
h
e
de
s
i
gn
a
nd
i
mp
l
e
me
nt
ati
on
of
s
ec
ure
s
oft
war
e
d
efi
ne
d
n
etwo
r
k
ar
c
hi
tec
tures
tha
t
c
a
n
s
o
l
v
e
t
he
prob
l
em
s
of
s
ec
urit
y
i
n
s
oft
war
e
de
fi
n
e
d
ne
t
wor
k
,
s
oft
w
are
d
efi
ne
d
ne
t
wor
k
i
s
s
ti
l
l
i
n
i
ts
i
nf
a
nc
y
an
d
f
urthe
r
r
es
ea
r
c
he
s
are
r
e
qu
i
r
ed
t
o
ad
dres
s
th
e
s
ec
uri
ty
c
ha
l
l
en
ge
s
t
o
t
he
c
e
ntral
i
z
ed
s
oft
war
e
de
f
i
n
ed
ne
twork
(
S
D
N)
c
on
tr
o
l
l
er.
A
s
oft
w
are
de
fi
n
ed
n
etw
o
r
k
as
a
ne
w
tec
h
no
l
og
i
c
al
ad
v
an
c
e
me
nt
i
n
ne
tw
ork
i
ng
,
i
s
s
up
po
s
ed
t
o
s
ol
v
e
th
e
tr
a
di
t
i
on
al
n
etwo
r
k
i
ng
c
om
p
l
e
x
i
ty
i
s
s
ue
s
by
break
i
ng
d
own
the
da
ta
forwar
di
ng
s
po
k
e
fr
o
m
th
e
brai
n
or
c
on
tr
ol
s
oft
wa
r
e.
B
ut
th
e
s
hi
ft
fr
o
m
the
tr
ad
i
t
i
on
al
to
the
s
oft
w
are
de
fi
n
ed
n
etwo
r
k
s
i
s
fac
i
ng
a
l
ot
of
prac
ti
c
al
i
mp
l
em
en
t
ati
on
pro
bl
em
s
.
O
ne
of
t
he
s
e
probl
em
s
i
s
s
ec
urit
y
i
s
s
u
es
as
s
oc
i
ate
d
w
i
th
c
en
tr
al
i
z
e
d
s
oft
war
e
de
f
i
ne
d
n
etwo
r
k
(
S
DN)
c
on
tr
ol
l
ers
[8]
.
S
oft
w
are
de
fi
ne
d
ne
twork
b
ei
n
g
a
pl
atf
orm
th
at
pr
ov
i
de
s
a
c
os
t
-
eff
ec
ti
v
e
mo
r
e
f
l
ex
i
bl
e
an
d
c
en
tr
al
l
y
c
on
tr
ol
l
ed
hi
gh
s
p
ee
d
ne
twork
s
erv
i
c
es
wh
en
c
om
pa
r
ed
w
i
th
the
tr
a
di
ti
o
na
l
n
etwo
r
k
[
9,
1
0],
h
as
a
l
s
o
i
ntro
du
c
ed
a
s
ec
urit
y
r
i
s
k
s
wh
i
c
h
are
th
e
ma
i
n
c
on
c
er
ns
i
n t
he
tra
di
t
i
o
na
l
ne
t
wor
k
an
d n
ew
s
ec
urit
y
r
i
s
k
s
.
Unl
i
k
e,
i
n
tr
ad
i
t
i
on
al
ne
tw
ork
s
where
ev
ery
de
v
i
c
e
i
s
m
an
ag
ed
by
a
pro
gram
em
b
ed
de
d
i
nto
th
e
d
ev
i
c
e
by
i
ts
ma
nu
f
ac
turer
,
i
n
s
of
t
war
e
de
fi
n
ed
ne
tw
ork
,
th
e
c
e
ntral
c
on
tr
o
l
l
er
i
s
us
ed
to
ma
na
ge
ea
c
h
de
v
i
c
e
i
n
th
e
ne
twork
.
A
n
d t
h
e d
ev
i
c
es
a
r
e c
on
ne
c
t
ed
t
o t
he
c
en
tr
al
c
on
tr
ol
l
er w
i
th
the
he
l
p
of
s
tan
da
r
d
pro
toc
ol
s
s
uc
h
as
the
O
pe
n
F
l
ow
protoc
o
l
.
T
h
i
s
m
ak
es
ne
twork
ma
na
ge
me
nt
ta
s
k
s
i
mp
l
e
r
an
d
be
tt
er n
etwo
r
k
f
l
ex
i
bi
l
i
t
y
an
d
progr
a
mm
ab
i
l
i
ty
. W
i
t
h t
h
i
s
ap
proac
h,
de
v
i
c
es
fr
o
m
di
ffe
r
en
t
v
e
n
do
r
s
m
ay
be
us
e
d
i
n
th
e
ne
t
wor
k
us
i
ng
th
i
s
s
ta
nd
ard
.
H
owev
er,
the
de
v
i
c
es
i
n
s
oft
war
e
d
efi
ne
d
n
etwo
r
k
c
an
r
ec
e
i
v
e
a
ma
n
i
pu
l
at
ed
f
l
ow
r
u
l
es
,
a
nd
po
l
i
c
i
es
fr
om
the
c
en
tr
al
i
z
ed
S
DN c
o
ntrol
l
er, th
i
s
i
s
o
ne
of
th
e s
ec
urit
y
r
i
s
k
i
n t
h
i
s
ap
pr
oa
c
h.
O
ne
of
th
e
mo
s
t
s
i
g
ni
f
i
c
a
nt
r
i
s
k
fac
tor
i
n
s
oft
w
are
de
fi
ne
d
ne
tw
ork
i
s
the
po
s
s
i
bi
l
i
ty
of
c
om
pro
mi
s
i
ng
the
S
D
N
c
on
tr
ol
l
er,
k
n
own
as
an
att
ac
k
on
th
e
c
on
tr
o
l
l
er.
Due
t
o
the
c
en
tr
al
i
z
ati
on
of
S
DN
c
on
tr
ol
l
er,
an
a
tta
c
k
er
c
a
n
c
on
tr
o
l
th
e
e
nti
r
e
ne
tw
o
r
k
i
f
the
S
DN
c
on
tr
ol
l
er
i
s
att
ac
k
ed
an
d
i
n
th
e
w
ors
t
c
as
es
th
e
en
ti
r
e
n
etwo
r
k
ma
y
g
o
d
own,
be
c
a
us
e,
the
att
ac
k
ers
m
ay
a
l
s
o
be
mo
t
i
v
at
ed
on
th
e
c
en
tr
al
i
z
ed
S
DN
c
on
tr
o
l
l
er
t
o
ma
n
i
pu
l
ate
or
al
t
er
the
ne
twork
.
T
he
S
DN
c
o
ntrol
l
ay
er
i
s
al
s
o
s
us
c
ep
t
i
bl
e
to
d
en
i
al
o
f
s
erv
i
c
e
att
ac
k
(
DO
S
)
,
an
att
ac
k
er
c
a
n
us
e
t
he
s
wi
tc
he
s
to
c
au
s
e
the
s
oft
war
e
de
f
i
ne
d
n
etw
ork
c
on
t
r
ol
pl
a
ne
to
be
fl
oo
de
d
wi
th
nu
m
erous
r
e
q
ue
s
ts
tha
t
p
os
s
i
bl
y
c
a
us
es
a
d
el
ay
or
dro
p
o
f
th
e
r
e
qu
es
ts
[1
1]
t
o
the
c
on
tr
o
l
l
er.
T
he
p
os
s
i
b
l
e
de
fen
s
e
ag
a
i
ns
t
t
o
th
i
s
form
of
att
ac
k
i
s
i
mp
l
e
me
n
ti
n
g
a
di
s
tr
i
bu
t
ed
ph
y
s
i
c
al
s
of
tware
de
f
i
ne
d n
etwo
r
k
c
on
tr
o
l
l
ers
.
T
he
c
ha
r
ac
teri
s
ti
c
fea
t
ures
of
s
ec
urit
y
r
i
s
k
s
an
d
c
ha
l
l
e
ng
es
i
n s
o
ftware
d
efi
ne
d
ne
twork
s
are
d
i
ff
erent
i
n
s
o
me
as
p
ec
ts
[12
]
fr
o
m
tha
t
o
f
t
he
tr
ad
i
t
i
on
al
n
etwo
r
k
,
du
e
t
o
the
p
arti
c
u
l
ar
ne
twork
i
m
pl
em
e
nta
t
i
o
n
an
d
S
DN’
s
c
ha
r
ac
ter
i
s
ti
c
c
o
n
tr
ol
an
d
pro
gram
ma
b
i
l
i
ty
c
ha
r
ac
teri
s
t
i
c
s
.
F
or
ex
am
pl
e,
th
e
c
on
c
ep
t
of
the
c
en
tr
a
l
i
z
e
d
c
on
tr
o
l
l
o
gi
c
ma
y
ex
po
s
e
t
he
f
l
ow
r
ul
es
an
d
c
on
fi
g
urat
i
on
fi
l
es
to
at
t
ac
k
ers
an
d
the
ab
i
l
i
ty
to
di
r
ec
tl
y
ac
c
es
s
th
e c
on
tr
o
l
p
l
a
ne
r
es
ul
ts
i
n a
ne
w
att
ac
k
s
urfac
e [
1
3]
a
nd
t
he
po
s
s
i
bi
l
i
ti
es
of
th
e e
nti
r
e
ne
twork
ge
tt
i
ng
do
wn.
S
ev
era
l
s
tud
i
es
[14
]
ha
v
e
att
em
pte
d
to
s
tu
dy
di
s
tr
i
bu
te
d
S
D
N
c
on
tr
o
l
l
ers
.
Howev
er,
de
s
pi
t
e
th
ei
r
a
tte
mp
t
at
d
i
s
tr
i
bu
ti
ng
t
he
c
o
ntrol
pl
an
e
,
the
y
r
eq
ui
r
e
a
c
on
s
i
s
t
en
t
ne
tw
ork
wi
de
v
i
ew
i
n
a
l
l
the
c
on
tr
o
l
l
ers
.
B
ut
di
s
tr
i
bu
t
i
on
of
t
he
c
o
nt
r
ol
l
ers
c
r
ea
t
es
an
oth
er
pro
bl
e
m,
th
at
i
s
,
s
y
nc
hroni
z
ati
on
of
d
i
s
tr
i
b
u
ted
S
D
N
c
on
tr
ol
l
ers
an
d
c
on
c
urr
en
c
y
c
on
tr
ol
i
n
a
hi
g
hl
y
dy
na
mi
c
s
oft
war
e
d
efi
ne
d
ne
tw
ork
en
v
i
r
on
me
n
t
i
s
c
ha
l
l
e
ng
i
ng
.
S
i
nc
e
th
e
S
D
N
s
wi
t
c
he
s
l
oo
k
to
the
c
on
tr
o
l
l
ers
for
an
s
wer
s
wh
i
l
e
ha
n
dl
i
ng
u
nfa
mi
l
i
ar
fl
ows
,
k
no
w
i
ng
w
hi
c
h
c
on
tr
ol
l
er
t
o
as
k
i
s
i
mp
ortant
.
M
oreov
er,
the
c
on
tr
ol
l
ers
t
he
ms
e
l
v
es
n
ee
d
to
ha
v
e
me
t
ho
do
l
og
i
es
t
o
de
c
i
de
who
c
on
tr
ol
s
wh
i
c
h
s
wi
tc
h,
a
n
d
who
r
ea
c
ts
to
wh
i
c
h
e
v
en
ts
.
A
nd
mo
s
t
of
a
l
l
,
c
on
s
i
s
ten
c
y
i
n
the
s
ec
ur
i
ty
p
ol
i
c
i
es
pres
en
t
on
th
e
c
o
ntrol
l
er
i
s
pa
r
am
ou
nt,
th
e
ab
s
en
c
e
of
wh
i
c
h
mi
g
ht
r
es
u
l
t
i
n
Evaluation Warning : The document was created with Spire.PDF for Python.
◼
IS
S
N: 16
93
-
6
93
0
T
E
L
KO
MNIK
A
V
ol
.
1
7
,
No
.
6
,
D
ec
em
b
er
20
19
:
31
68
-
31
74
3170
att
ac
k
ers
us
i
n
g
a
pp
l
i
c
at
i
o
n
tr
av
ers
i
n
g
ac
r
os
s
mu
l
t
i
pl
e
pa
r
t
i
ti
on
s
o
f
th
e
S
D
N
en
v
i
r
o
nm
en
t
wi
th
ou
t
pe
r
m
i
s
s
i
on
s
.
3.
S
DN
S
ec
u
r
it
y Cl
as
sificati
o
n
T
he
s
ep
arat
i
on
of
c
on
tr
o
l
l
o
gi
c
fr
om
the
da
ta
pl
a
ne
i
n
S
DN
h
as
i
ntrod
uc
e
d
n
ew
v
ul
ne
r
a
bi
l
i
t
i
es
,
w
hi
c
h
are
n
ot
fou
nd
i
n
th
e
tr
ad
i
ti
on
a
l
n
etwo
r
k
.
F
or
ex
am
pl
e
,
the
u
s
e
of
tr
an
s
po
r
t
l
ay
er
s
ec
urit
y
i
s
op
ti
o
na
l
i
n
the
O
pe
nFl
o
w
ne
t
wor
k
.
T
he
na
t
ure
of
t
he
c
o
mm
u
ni
c
ati
on
protoc
o
l
c
an
thu
s
i
ntrod
uc
e
s
ec
urit
y
i
s
s
ue
s
s
uc
h
as
DoS
att
ac
k
,
fak
e
fl
o
w
r
ul
e
i
ns
ert
i
o
n,
an
d
ev
e
n
fl
ow
r
ul
e
al
terat
i
on
[1
5].
F
i
g
ure
1
de
mo
ns
tr
at
es
th
e
di
ff
erent
c
o
mp
on
e
nts
of
S
DN:
(
1)
ap
p
l
i
c
a
ti
o
n
l
ay
er,
(
2)
c
o
ntrol
l
ay
er
an
d
(
3)
i
nfras
tr
uc
ture
l
ay
ers
,
wh
i
c
h
are
ex
po
s
e
d
to
att
ac
k
s
.
F
or
ex
am
pl
e,
the
r
e
c
an
b
e
s
oft
w
are
v
ul
n
erabi
l
i
ti
es
i
n
S
D
N
c
on
tr
o
l
l
ers
,
s
uc
h
as
P
O
X
wh
i
c
h
c
an
be
ex
pl
oi
ted
by
an
att
ac
k
er
to
p
erfor
m
a
n
att
ac
k
on
c
on
tr
o
l
p
l
an
e
.
A
dd
i
ti
on
a
l
l
y
,
t
he
c
om
mu
ni
c
at
i
on
p
ath
s
be
twe
en
th
e
thre
e
l
ay
ers
i
n
the
S
DN
,
t
h
e
no
r
th
bo
un
d
i
nt
erfac
es
c
on
ne
c
t
i
ng
t
he
c
on
tr
ol
l
er
wi
t
h
ap
p
l
i
c
at
i
on
l
ay
er
an
d
t
he
s
ou
th
bo
u
nd
i
n
terfac
es
c
on
n
ec
ti
ng
t
he
i
n
fr
as
tr
uc
ture
l
ay
er
to
th
e
S
DN
c
on
tr
ol
l
er,
c
a
n
fac
e
s
ec
ur
i
ty
att
ac
k
s
.
S
o
me
of
t
he
po
s
s
i
bl
e
a
tta
c
k
s
ag
a
i
ns
t
ea
c
h
l
ay
er
of
the
s
oft
war
e d
efi
ne
d n
e
two
r
k
is
di
s
c
us
s
ed
i
n d
e
tai
l
b
el
ow
:
-
A
pp
l
i
c
at
i
o
n
l
ay
er
s
ec
urit
y
:
T
he
ap
p
l
i
c
a
ti
o
ns
i
m
pl
e
me
n
ted
for
th
e
ad
a
pta
t
i
o
n
an
d
oth
er
S
DN
op
erat
i
o
ns
c
an
ha
v
e
s
ec
ur
i
ty
v
ul
ne
r
a
bi
l
i
t
i
es
.
A
l
l
th
e
s
e
c
urit
y
i
s
s
ue
s
tha
t
c
an
b
e
p
r
es
en
t
i
n
a
ty
pi
c
al
s
of
tware
ap
p
l
i
c
at
i
o
n
s
uc
h
as
,
a
b
uff
er
ov
erf
l
ow
att
ac
k
al
s
o
ap
pl
y
to
t
he
s
oft
w
are
de
fi
ne
d
ne
tw
ork
.
A
nd
t
he
ma
l
i
c
i
o
us
or
a
c
om
pro
mi
s
e
d
ap
p
l
i
c
at
i
o
n
al
l
ow
b
l
o
wout
of
att
ac
k
i
n
the
c
om
pl
ete
ne
tw
ork
[1
6].
-
Cont
r
o
l
l
ay
er
s
ec
urit
y
:
T
he
c
on
tr
ol
pl
an
e
c
o
ns
i
s
ts
of
o
ne
or
m
ore
c
on
tr
ol
l
ers
,
s
uc
h
as
NO
X
,
P
O
X
,
an
d
o
the
r
progr
a
ms
us
ed
f
or
m
an
a
gi
ng
t
he
i
n
fr
as
tr
uc
ture
l
ay
er
d
ev
i
c
e
an
d
ha
nd
l
i
ng
di
ff
erent
k
i
nd
s
o
f
prot
oc
ol
s
s
uc
h
as
,
th
e
O
pe
nFl
o
w.
T
he
att
ac
k
er
c
an
g
en
era
te
tr
aff
i
c
fr
o
m
s
po
ofe
d
I
P
ad
dres
s
an
d
s
e
nd
a
hu
g
e
v
o
l
um
e
of
tr
aff
i
c
to
th
e
c
on
tr
ol
l
er
as
d
i
s
c
us
s
ed
by
[17
].
B
y
pe
r
f
ormi
ng
s
uc
h a
tta
c
k
s
, th
e
c
om
mu
n
i
c
at
i
on
b
etwe
en
t
he
s
w
i
tc
h
an
d t
h
e c
o
ntr
ol
l
er c
an
be
s
atu
r
ate
d
,
th
us
i
nc
r
ea
s
i
ng
s
erv
i
c
e
l
at
en
c
y
or
i
n
th
e
wor
s
t
c
as
e
bri
ng
i
ng
do
w
n
the
S
DN
c
on
tr
ol
l
er wh
i
c
h res
u
l
ts
i
n t
he
e
nti
r
e
ne
t
wor
k
ge
tt
i
n
g d
own.
-
Inf
r
as
tr
uc
ture
l
ay
er
s
ec
urit
y
:
an
att
ac
k
er
c
an
de
l
ay
tr
aff
i
c
be
twee
n
the
S
DN
c
o
ntrol
l
er
an
d
i
nfras
tr
uc
ture
l
ay
er
by
g
en
e
r
ati
ng
n
etwo
r
k
tr
af
fi
c
w
i
th
p
oi
s
on
ed
ad
dres
s
es
an
d
for
war
di
ng
t
he
tr
aff
i
c
t
o
the
c
on
tr
o
l
l
er
t
o
ov
erlo
a
d
i
t
[18
].
B
uf
fer
ov
erfl
o
w
att
ac
k
i
s
an
oth
er
po
s
s
i
bl
e
at
tac
k
o
n
i
nfras
tr
uc
ture
l
ay
er.
T
he
s
wi
tc
he
s
are
r
es
po
ns
i
b
l
e
fo
r
forwar
di
n
g
da
t
a
bu
t,
f
ak
e
fl
ow
r
u
l
es
ge
ne
r
ate
d
by
att
ac
k
er
c
an
ov
erfl
ow
t
he
s
wi
tc
h’
s
fl
ow
t
ab
l
e
s
i
nc
e
t
he
y
ha
v
e
l
i
m
i
te
d m
em
ory
.
-
T
he
C
om
m
un
i
c
ati
o
n
C
ha
nn
el
s
s
ec
ur
i
ty
:
T
h
e
c
om
m
un
i
c
ati
on
c
h
an
n
el
be
tw
ee
n
the
i
nfras
tr
uc
ture
l
ay
er
d
ev
i
c
es
,
s
uc
h
as
s
wi
tc
h
es
an
d
t
he
S
DN
c
o
ntrol
l
er
,
whi
c
h
i
s
the
s
ou
t
hb
o
un
d
i
nte
r
f
ac
e
,
the
S
D
N
c
on
tr
o
l
l
er
a
nd
the
ap
p
l
i
c
at
i
o
n
l
ay
er,
whi
c
h
i
s
the
no
r
t
hb
o
un
d
i
nte
r
f
ac
e
a
r
e
ex
po
s
ed
to
a
m
an
-
in
-
th
e
-
mi
d
dl
e
att
ac
k
as
s
ho
wc
a
s
ed
i
n
[1
9],
the
s
w
i
tc
h’
s
f
l
ow
tab
l
e
c
an
ev
en
be
f
i
l
l
e
d
w
i
th
a
f
ak
e
fl
ow
r
ul
es
an
d
by
po
i
s
on
i
ng
th
e
f
l
ow
tab
l
e,
tr
a
ffi
c
c
a
n
b
e
r
ed
i
r
ec
ted
t
o
a
ma
n
i
n
t
he
mi
dd
l
e.
O
the
r
a
tta
c
k
s
r
es
ea
r
c
he
d
by
au
t
ho
r
s
tha
t
c
a
n
be
pe
r
for
me
d
on
t
he
c
o
mm
u
ni
c
at
i
o
n
c
ha
nn
e
l
i
nc
l
ud
e
e
av
es
drop
pi
n
g
tr
a
f
fi
c
be
twe
en
ho
s
ts
,
a
nd
s
tea
l
th
i
l
y
mo
di
fy
i
ng
the
tr
af
fi
c
be
tw
e
en
ho
s
ts
as
th
ey
tr
av
er
s
e
thro
ug
h
the
p
hy
s
i
c
al
c
o
mm
u
ni
c
a
ti
o
n c
ha
n
ne
l
.
3.1.
Cent
r
ali
z
ed
S
DN
Co
n
t
r
o
ll
er
In
th
i
s
s
ec
ti
on
,
we
w
i
l
l
bri
ef
l
y
i
ntro
du
c
e
th
e
c
en
tr
a
l
i
z
ed
S
DN
c
on
tr
ol
l
er
arc
hi
t
ec
tur
e
an
d
the
s
ec
ur
i
ty
c
ha
l
l
en
g
es
a
s
s
oc
i
ate
d
wi
t
h
t
hi
s
arc
hi
t
ec
ture,
prim
aril
y
on
th
e
c
on
tr
ol
l
ay
er.
T
he
c
en
tr
a
l
i
z
ed
S
DN
c
on
tr
ol
l
er
arc
hi
tec
t
ure
i
s
i
l
l
us
t
r
ate
d
i
n
F
i
g
ure
1.
A
s
d
e
mo
ns
tr
at
ed
i
n
F
i
gu
r
e
1,
th
e
arc
h
i
tec
ture
i
s
l
ay
ered
i
nto
thre
e
l
ay
ers
,
the
c
on
tr
ol
l
er,
ap
p
l
i
c
a
ti
o
n
an
d
n
etwo
r
k
i
nfras
tr
uc
ture,
an
d we
fo
c
u
s
on
th
e s
ec
urit
y
i
s
s
u
es
on
c
on
tr
ol
l
er.
T
he
c
en
tr
al
i
z
ed
c
o
ntrol
or
l
og
i
c
a
l
l
y
c
e
ntral
i
z
ed
c
on
tr
o
l
tha
t
i
s
,
d
i
s
tr
i
b
ute
d
bu
t
c
oo
r
di
n
ate
d
c
on
tr
ol
fun
c
t
i
on
ex
p
os
es
t
he
da
ta
s
uc
h
as
c
on
f
i
g
ura
ti
on
f
i
l
e
,
v
u
l
ne
r
a
bl
e
t
o
th
e
att
ac
k
ers
[20
].
A
tta
c
k
ers
ma
y
att
e
mp
t
t
o
op
erat
e
th
e
c
om
mo
n
ne
tw
ork
s
erv
i
c
es
or
ev
en
c
on
t
r
ol
th
e
e
nti
r
e
ne
twork
by
m
i
s
l
e
ad
i
ng
or
c
om
prom
i
s
i
n
g
th
e
c
on
tr
o
l
l
e
r
w
hi
c
h
i
s
the
h
ea
r
t
o
f
the
ne
twork
.
T
he
c
en
tr
a
l
i
z
e
d
arc
h
i
tec
t
ure
of
S
DN
c
o
ntrol
l
er
an
d
l
ac
k
of
d
efe
nd
ers
c
ap
ab
i
l
i
ty
,
an
d
un
de
v
e
l
o
pe
d
tec
h
no
l
og
y
p
os
s
i
bl
y
w
i
l
l
be
ne
f
i
t
the
att
ac
k
ers
.
F
or
i
ns
tan
c
e,
th
e
i
ntrod
uc
ti
on
of
ma
l
i
c
i
o
us
c
on
tr
o
l
l
er
pr
og
r
a
ms
ma
y
al
l
ow
a
w
i
de
r
i
m
pa
c
t
o
f
t
he
att
ac
k
[
21
].
T
he
s
o
l
ut
i
on
to
Evaluation Warning : The document was created with Spire.PDF for Python.
T
E
L
KO
MNIK
A
IS
S
N: 1
69
3
-
6
93
0
◼
A
r
ev
i
e
w on
s
oft
war
e d
e
fi
n
ed
n
etwo
r
k
s
ec
urit
y
r
i
s
k
s
a
nd
c
ha
l
l
en
g
es
(
T
s
eh
ay
A
d
ma
s
s
u A
s
s
eg
i
e
)
3171
thi
s
i
s
s
ue
i
s
s
tori
n
g
th
e
c
r
i
ti
c
al
c
o
nfi
gu
r
at
i
on
fi
l
e
s
an
d
th
e
fl
ow
r
u
l
es
i
n
a
c
om
p
l
et
el
y
di
s
tr
i
b
ute
d
c
on
tr
o
l
do
ma
i
n.
T
he
d
i
s
tr
i
bu
ted
S
DN
c
o
ntr
ol
l
er
arc
hi
t
ec
ture
i
s
di
s
c
us
s
ed
i
n
d
et
ai
l
i
n
the
f
ol
l
ow
i
ng
s
ec
t
i
o
n.
A
no
t
he
r
i
s
s
ue
w
i
th
s
oft
w
ar
e
de
fi
ne
d
ne
tw
ork
aris
es
fr
om
i
ts
fl
ex
i
bi
l
i
ty
.
T
he
i
nc
r
ea
s
ed
fl
ex
i
bi
l
i
ty
de
c
r
ea
s
es
t
he
po
s
s
i
bi
l
i
ty
of
s
tr
on
g
er
d
efe
nd
i
ng
me
c
h
an
i
s
m
f
or
th
e
s
of
tware
de
f
i
ne
d
ne
twork
.
B
ec
au
s
e
of
th
i
s
fea
ture
th
e
S
DN
b
ec
om
es
dy
na
mi
c
an
d
i
n
s
uc
h
c
on
fi
gu
r
ati
on
s
the
s
tat
e
of
t
he
s
y
s
tem
i
s
d
i
ffi
c
u
l
t
t
o
de
t
erm
i
ne
.
T
hi
s
w
i
l
l
c
r
ea
t
e
an
op
po
r
tu
ni
ty
for
the
at
tac
k
ers
,
on
c
e
th
ey
ga
i
n
ac
c
es
s
i
nto
the
s
y
s
tem
;
i
d
en
t
i
f
i
c
ati
on
of
th
e
l
eg
i
ti
ma
te
us
ers
fr
o
m
the
att
ac
k
er
i
s
di
f
fi
c
u
l
t.
F
i
gu
r
e
1
.Th
e Ce
ntral
i
z
ed
S
DN
c
on
tr
o
l
l
er ar
c
hi
t
ec
ture
[
22
,
2
3]
3.2.
Distribu
t
ed
S
DN Co
n
t
r
o
l
l
er
T
hi
s
s
ec
ti
o
n
d
i
s
c
us
s
es
s
oft
war
e
de
fi
ne
d
ne
tw
ork
c
on
tr
ol
l
er
i
mp
l
em
en
ta
ti
o
n
o
pti
on
s
an
d
the
prop
os
ed
d
i
s
tr
i
bu
ted
s
oft
war
e
d
efi
ne
d
n
etw
ork
c
on
tr
ol
l
er
arc
hi
tec
ture.
W
h
i
l
e
the
s
oft
war
e
de
fi
ne
d
ne
tw
ork
c
on
tr
ol
l
er
c
en
tr
al
i
z
ati
on
h
as
s
ol
v
ed
t
he
prob
l
e
ms
of
n
etwo
r
k
m
an
ag
ea
b
i
l
i
ty
i
t
ha
s
c
r
ea
te
d
a
c
o
mp
r
o
mi
s
e
an
d
ma
y
c
au
s
e
s
i
ng
l
e
po
i
nt
of
f
ai
l
ure
i
f
t
he
s
y
s
tem
i
s
c
om
prom
i
s
ed
by
ma
l
i
c
i
ou
s
gu
y
s
or a
tta
c
k
ers
.
T
he
orig
i
na
l
de
s
i
gn
of
S
D
N
was
ba
s
ed
o
n
a
c
e
ntral
i
z
e
d
c
on
tr
ol
p
l
an
e
as
th
e
o
bj
e
c
ti
v
e
of
S
DN
i
s
t
o
s
e
pa
r
at
e
t
he
c
on
tr
ol
pl
an
e
fr
om
t
he
da
t
a
pl
a
ne
an
d
a
l
l
ow
t
he
g
l
ob
al
v
i
e
w
of
th
e
w
ho
l
e
ne
twork
.
T
h
i
s
al
l
ows
t
he
c
on
tr
ol
l
er
w
i
th
a
c
om
pr
eh
e
ns
i
v
e
n
et
wor
k
-
wi
d
e
v
i
ew
a
nd
pe
r
mi
ts
for
the
de
v
el
op
me
nt
of
c
on
tr
o
l
ap
p
l
i
c
at
i
on
s
an
d f
or
ea
s
i
er
po
l
i
c
y
en
f
orc
em
en
t. H
owev
er, c
en
tr
a
l
i
z
i
ng
the
c
on
tr
ol
pl
a
ne
i
n
S
DN
i
s
fr
au
g
ht
w
i
th
s
c
al
ab
i
l
i
ty
an
d
s
ec
uri
ty
c
ha
l
l
e
ng
es
a
s
s
oc
i
ate
d
w
i
th
the
S
DN c
on
tr
ol
l
er b
ei
ng
a
bo
tt
l
en
ec
k
[2
4].
S
ec
ure
s
of
tware
de
f
i
ne
d
ne
twork
arc
h
i
tec
ture
c
an
s
ol
v
e
th
e
pro
bl
e
ms
of
s
e
c
urit
y
i
n
s
o
ftware
de
fi
ne
d
ne
twor
k
[25
]
at
the
c
on
tr
ol
l
ay
er.
B
u
t
a
s
ol
uti
on
to
th
i
s
pro
bl
e
m
r
e
qu
i
r
es
an
i
n
-
de
pt
h
l
on
g
-
t
erm
r
es
e
arc
h.
W
i
tho
ut
th
e
us
e
of
a
s
ec
ure
arc
hi
tec
tur
e
for
S
D
N,
the
c
on
tr
ol
l
er
pl
a
ne
i
s
at
r
i
s
k
.
S
om
e
of
th
e
s
ol
uti
on
s
pro
po
s
e
d
to
de
al
w
i
th
th
e
s
ec
urit
y
i
s
s
ue
s
o
n
th
e
c
on
tr
ol
l
er
l
ay
er ar
e:
-
Har
de
n
i
n
g
th
e
c
on
tr
o
l
l
o
gi
c
progr
am
o
n
th
e
S
D
N
c
on
tr
ol
l
er
-
th
i
s
de
al
s
w
i
th
ma
k
i
n
g
the
c
o
ntrol
l
er
i
ts
e
l
f
s
ec
ur
e
f
r
om
a
ny
for
m
of
at
tac
k
.
A
s
the
r
e
i
s
n
o
c
o
mp
l
ete
l
y
s
ec
ure
s
y
s
tem
tha
t
i
s
ev
er
bu
i
l
t
s
i
nc
e,
t
hi
s
i
s
v
ery
c
om
pl
ex
an
d
on
e
da
y
th
e
S
DN
c
o
ntro
l
l
er
ma
y
b
e
c
om
prom
i
s
ed
.
-
Dec
en
tr
a
l
i
s
i
ng
the
S
DN
c
o
ntrol
l
er
-
a
c
om
pl
e
tel
y
di
s
tr
i
bu
te
d
i
mp
l
e
me
nt
ati
on
of
S
DN
c
on
tr
o
l
l
er
arc
hi
tec
ture
c
an
s
ol
v
e
th
e
probl
em
wi
t
h
c
e
ntral
i
z
ed
S
DN
c
on
tr
o
l
l
er.
H
owev
er,
th
e
c
om
pl
ex
i
ty
of
n
etwo
r
k
ma
n
ag
e
me
n
t
wi
l
l
i
nc
r
ea
s
e
as
a
r
e
s
ul
t
o
f
S
DN
c
o
ntrol
l
er
di
s
tr
i
b
uti
on
.
T
he
d
i
s
tr
i
bu
ted
S
DN
c
on
tr
o
l
l
er
arc
hi
tec
t
ure i
s
de
m
on
s
t
r
ate
d
i
n
F
i
gu
r
e
2.
Cent
r
a
l
i
z
e
d
arc
hi
t
ec
ture
o
f
the
S
DN
c
on
tr
ol
l
er
c
r
ea
tes
ad
di
t
i
on
al
c
o
mp
l
ex
i
t
y
an
d
c
ha
l
l
en
g
es
for
s
ec
ur
i
ty
c
o
ntrol
s
o
n
t
he
c
o
ntrol
l
ay
er
.
A
s
s
ho
r
t
l
i
s
ted
i
n
[26
]
,
t
he
r
e
ar
e
thre
e
op
ti
on
s
to
i
mp
l
em
en
t
th
e
S
DN
c
on
tr
ol
l
er
arc
hi
t
ec
tures
,
c
en
tr
al
i
z
ed
,
d
ec
en
tr
a
l
i
z
e
d
or
di
s
tr
i
bu
t
ed
Evaluation Warning : The document was created with Spire.PDF for Python.
◼
IS
S
N: 16
93
-
6
93
0
T
E
L
KO
MNIK
A
V
ol
.
1
7
,
No
.
6
,
D
ec
em
b
er
20
19
:
31
68
-
31
74
3172
an
d
mu
l
t
i
-
l
ay
er
arc
hi
t
ec
ture
s
bu
t,
i
t
i
s
c
om
m
on
to
c
ou
pl
e
s
oft
w
are
de
f
i
ne
d
n
etw
o
r
k
arc
hi
tec
ture
wi
th
a c
en
tr
a
l
i
z
ed
S
DN c
o
n
tr
ol
to
de
pl
oy
ne
tw
ork
s
erv
i
c
es
or app
l
i
c
at
i
o
ns
.
A
s
s
ho
wn
i
n
F
i
gu
r
e
1,
the
s
oft
war
e
de
fi
n
ed
n
etwo
r
k
a
r
c
hi
tec
ture,
wh
i
c
h
i
s
prop
o
s
ed
by
the
o
pe
n
ne
t
wor
k
fou
nd
a
ti
on
(
O
NF
)
,
c
on
s
i
s
ts
of
thre
e
l
ay
ers
,
n
am
el
y
th
e
a
pp
l
i
c
ati
o
n,
t
he
S
DN
c
on
tr
ol
l
er
an
d
th
e
d
ata
for
wa
r
di
ng
l
ay
er
an
d
t
he
s
e
l
ay
ers
are
v
u
l
ne
r
ab
l
e
t
o
at
tac
k
.
A
n
d
t
hi
s
v
ul
ne
r
a
bi
l
i
ty
s
pe
c
i
al
l
y
,
t
he
c
on
tr
o
l
l
ay
er
v
ul
n
erab
i
l
i
t
y
c
an
be
us
ed
by
att
ac
k
ers
to
g
ai
n
un
au
tho
r
i
z
ed
ac
c
es
s
to
t
h
e
S
DN
c
o
ntrol
l
er,
to
i
n
ter
c
ep
t
a
nd
ma
ni
p
ul
ate
ne
tw
ork
tr
aff
i
c
.
F
or
ex
am
p
l
e,
t
h
e
us
e
of
pre
-
c
on
fi
gu
r
e
d
c
l
ea
r
t
ex
t
s
he
l
l
a
c
c
es
s
on
s
wi
tc
h
es
r
un
ni
ng
on
L
i
nu
x
an
d
the
ou
tda
t
ed
S
S
L
i
mp
l
e
me
nta
t
i
on
p
uts
the
e
nti
r
e
s
of
t
war
e
de
f
i
ne
d
ne
t
wor
k
s
y
s
tem
at
r
i
s
k
.
A
pa
r
t
fr
om
th
at,
the
i
n
tr
od
uc
t
i
on
o
f s
oft
war
e
de
fi
n
ed
ne
tw
ork
f
un
c
ti
o
ns
c
an
i
nc
r
ea
s
e
th
e a
tta
c
k
s
urfac
e.
A
s
ec
urit
y
breac
h
i
n
th
es
e
ap
p
l
i
c
at
i
on
s
e
na
b
l
es
an
att
ac
k
er
to
ev
ad
e
i
s
o
l
at
i
o
n
m
ec
ha
n
i
s
ms
an
d
c
om
prom
i
s
e t
he
c
om
pl
ete
ne
twork
or
ex
ec
ute
i
l
l
e
ga
l
a
c
ti
on
s
o
n o
t
he
r
n
etwo
r
k
s
[2
7].
T
he
c
en
tr
a
l
i
z
a
ti
o
n
o
f
th
e
c
on
tr
ol
l
o
gi
c
c
r
ea
t
es
ad
d
i
t
i
on
al
s
ec
ur
i
ty
r
i
s
k
s
to
th
e
S
DN
c
on
tr
ol
l
er,
i
f
thi
s
c
ore
c
o
mp
on
en
t
of
the
s
o
ftware
de
fi
ne
d
ne
tw
ork
i
s
c
om
promi
s
e
d,
th
en
the
en
ti
r
e
S
DN
n
etwo
r
k
i
s
a
t
r
i
s
k
of
fai
l
ure.
T
h
ere
are
t
wo
s
ec
urit
y
r
i
s
k
s
wi
th
th
e
c
en
tr
al
i
z
at
i
on
of
S
DN
c
o
ntrol
l
er,
t
he
s
e
are
,
1)
th
e
c
on
t
r
o
l
l
er
i
ts
e
l
f
i
s
prone
to
att
ac
k
s
,
s
uc
h
a
s
DDO
S
a
nd
fl
oo
di
ng
,
2)
ma
l
i
c
i
ou
s
f
l
ow
r
ul
es
c
an
be
ge
n
erate
d
a
n
d
forwar
d
ed
t
o
t
he
f
orw
ard
i
ng
pl
an
e,
as
the
r
e
i
s
n
o
me
c
ha
ni
s
m
us
e
d
to
i
de
nt
i
fy
w
hi
c
h
fl
ow
po
l
i
c
es
are
g
en
u
i
n
e
a
nd
wh
i
c
h
are
ma
l
i
c
i
ou
s
,
thi
s
c
r
ea
tes
a
p
r
ob
l
em
o
n
the
ne
t
wor
k
.
T
h
i
s
i
s
b
ec
au
s
e,
o
nc
e
t
he
c
on
tr
o
l
l
er
i
s
c
om
pro
mi
s
e
d
i
t
c
an
trans
m
i
t a
ma
l
i
c
i
ou
s
f
l
o
w r
ul
es
t
o t
h
e n
e
twork
e
l
em
en
ts
i
n s
oft
w
are d
efi
ne
d
ne
t
wor
k
.
In
[28
],
c
om
prehe
ns
i
v
e
s
ec
urit
y
arc
hi
t
ec
ture
was
r
ec
o
mm
e
nd
e
d
to
pr
ov
i
de
a
v
ari
ety
of
s
ec
u
r
i
ty
s
erv
i
c
es
whi
c
h
al
s
o
i
nc
l
u
de
s
the
i
mp
l
e
me
nt
a
ti
on
o
f
r
eq
u
i
r
ed
n
etwo
r
k
s
ec
urit
y
po
l
i
c
i
es
,
pa
c
k
et
d
ata
s
c
an
d
ete
c
ti
on
m
ec
ha
n
i
s
ms
,
a
l
ter
i
n
g
ne
twork
p
ol
i
c
i
es
i
nt
o
fl
o
w
e
ntri
es
,
au
th
en
t
i
c
ati
on
an
d
au
t
ho
r
i
z
ati
on
for
ad
dres
s
i
ng
th
e
s
ec
urit
y
c
ha
l
l
en
g
es
r
el
ate
d
to
p
ol
i
c
y
en
forc
em
en
t
an
d
at
t
ac
k
de
t
ec
ti
on
i
n
a
s
oft
war
e
de
f
i
ne
d
ne
tw
ork
.
F
i
gu
r
e
2
.
T
h
e
d
i
s
tr
i
bu
ted
S
DN
c
on
tr
o
l
l
er ar
c
hi
t
ec
ture
[
29
]
4.
S
DN
S
ec
u
r
it
y Fr
amew
o
r
k
A
s
di
s
c
us
s
ed
i
n
ea
r
l
i
er
s
ec
ti
on
s
,
the
us
e
o
f
s
oft
w
are
de
fi
n
ed
ne
tw
ork
,
es
p
ec
i
al
l
y
the
c
e
ntra
l
i
z
ed
S
DN
c
on
tr
ol
l
er
arc
h
i
tec
ture
ex
p
os
es
the
c
o
ntro
l
l
er
to
d
i
ffe
r
en
t
f
orms
of
at
tac
k
s
l
i
k
e,
D
DO
S
,
s
wi
tc
h
fl
ow
tab
l
e
fl
oo
d
i
n
g,
i
ns
erti
o
n
o
f
fak
e
fl
ow
r
ul
e
an
d
s
o
on
.
T
h
i
s
ha
s
en
c
ou
r
a
ge
d
the
r
es
ea
r
c
he
r
s
to
the
de
pl
oy
me
nt
of
a
v
arie
ty
of
n
etwo
r
k
s
e
c
u
r
i
ty
fun
c
t
i
on
s
,
i
ntrus
i
on
de
t
ec
ti
o
n
a
nd
prev
en
ti
on
s
y
s
tem
s
,
an
d
ac
c
es
s
c
on
tr
ol
a
nd
i
d
en
t
i
ty
ma
na
ge
me
nt
i
n
the
s
oft
w
are
de
f
i
n
ed
n
etw
ork
to
protec
t
th
e
S
DN
c
on
tr
ol
l
er
a
nd
ev
e
n
al
l
of
t
he
l
ay
ers
form
di
ff
erent
forms
of
a
tta
c
k
s
.
T
he
arc
h
i
tec
ture
of
the
pre
l
i
mi
na
r
y
s
oft
w
are
de
f
i
ne
d
n
etwo
r
k
s
ec
urit
y
fr
am
ew
ork
foc
us
es
on
th
e
fun
c
ti
on
s
of
the
fr
a
me
wor
k
s
[30
]
de
p
l
oy
me
nt
a
r
c
hi
tec
ture
i
s
de
mo
ns
tr
ate
d i
n
F
i
gu
r
e
3 a
nd
s
om
e o
f
the
fr
am
e
wor
k
s
are d
i
s
c
us
s
ed
be
l
ow
:
Evaluation Warning : The document was created with Spire.PDF for Python.
T
E
L
KO
MNIK
A
IS
S
N: 1
69
3
-
6
93
0
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[31]
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two
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;
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74
-
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8
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2
]
O
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9
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work
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;
3
2
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):
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-
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.
[3
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]
Rom
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.
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