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Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

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Defending Against Low-rate TCP Attack: Dynamic Detection and Protection. Prof. John C.S. Lui CSE Dept. CUHK. Introduction to Low-rate TCP Attack Formal Description of Low-rate TCP Attack Distributed Dynamic Detection Low-rate Attack Defense Mechanism Fluid Model of TCP Flows - PowerPoint PPT Presentation
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Defending Against Low-rate TCP Attack: Dynamic Detection and Protection Prof. John C.S. Lui CSE Dept. CUHK
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Page 1: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

Defending Against Low-rate TCP Attack:Dynamic Detection and Protection

Prof. John C.S. LuiCSE Dept. CUHK

Page 2: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.2.

Outline

Introduction to Low-rate TCP Attack Formal Description of Low-rate TCP AttackDistributed Dynamic Detection Low-rate Attack Defense Mechanism Fluid Model of TCP FlowsDefence ExperimentsRelated Work & Conclusion

Page 3: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.3.

Introduction to the Low-rate TCP Attack

Common DoS attackConsume resources (bandwidth, buffer …etc) Keep legitimate users away form serviceLarge number of machines or agents are involvedHarmful, but relatively easy to be detected

Consume resources (bandwidth, buffer …etc) Keep legitimate users away form serviceLarge number of machines or agents are involvedHarmful, but relatively easy to be detected

Low-rate DoS attackAim to deny the bandwidth of legitimate TCP flowsAttacker sends the attack stream with low volumeExploit the TCP congestion control feature Attacker sends a periodic short burst to

victim/router

Aim to deny the bandwidth of legitimate TCP flowsAttacker sends the attack stream with low volumeExploit the TCP congestion control feature Attacker sends a periodic short burst to

victim/router

Page 4: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.4.

TCP Retransmission Mechanism

TCP congestion control

If under severe network congestion:Wait till transmission timeout (RTO) Reduce the congestion window

double the RTO

retransmit the packetIf succeed, enter slow start phase

else, exponential back off again

If under severe network congestion:Wait till transmission timeout (RTO) Reduce the congestion window

double the RTO

retransmit the packetIf succeed, enter slow start phase

else, exponential back off again

Calculation of RTO

In RFC 2988:

RTO=max(minRTO,SRTT+max(G,4RTTVAR))

Usually, RTO = minRTO when slow start

minRTO=1 second (recommended in RFC 2988)

In RFC 2988:

RTO=max(minRTO,SRTT+max(G,4RTTVAR))

Usually, RTO = minRTO when slow start

minRTO=1 second (recommended in RFC 2988)

Page 5: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.5.

Low-rate DoS Attack to TCP Flow A example of low-rate DoS attack

Sufficiently large attack burstPacket loss at congested routerTCP waits until timeout & retransmit after RTO Attack period = RTO of TCP flow,TCP continually incurs loss & achieves zero or

very low throughput.

Sufficiently large attack burstPacket loss at congested routerTCP waits until timeout & retransmit after RTO Attack period = RTO of TCP flow,TCP continually incurs loss & achieves zero or

very low throughput.

TCP

Avg BW= lR/T

Page 6: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.6.

What is the next?

Introduction to Low-rate TCP Attack Formal Description of Low-rate TCP AttackDistributed Dynamic Detection Low-rate Attack Defense Mechanism Fluid Model of TCP FlowsDefence ExperimentsRelated Work & Conclusion

Page 7: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.7.

T: Attack period

l: Length of burst

R: Rate of burst

N: Background noise

S: Time shift

T: Attack period

l: Length of burst

R: Rate of burst

N: Background noise

S: Time shift

l

Formal Description

Mathematical Description

N

R

T

S

Page 8: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.8.

Low-rate DoS Traffic Pattern The periodic burst may have different patterns:

Step-like double rate stream (Kuzmanovic & Knightly in Sigcomm 03)

Simple Square wave (Kuzmanovic & Knightly in Sigcomm 03)

General peaks with background noise

Page 9: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.9.

Low-rate DoS Traffic Pattern

Attack traffic is not easy to remain the same as the original at the victim router.Attack traffic between different period may not be the same, thus T, l, R may vary.

We need a “We need a “ROBUST ROBUST ” method ” method to identify all possible forms to identify all possible forms of attackof attack

Page 10: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.10.

Low-rate DoS Traffic Pattern Multiple distributed attack sources

Long Period combination

Small Burst combination

Page 11: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.11.

What is the next?

Introduction to Low-rate TCP Attack Formal Description of Low-rate TCP AttackDistributed Dynamic Detection Low-rate Attack Defense Mechanism Fluid Model of TCP FlowsDefence ExperimentsRelated Work & Conclusion

Page 12: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.12.

Dynamic DetectionOverall Idea of Dynamic Detection

Page 13: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.13.

Dynamic Detection

Traffic signature DetectionSmall average throughput => Throughput based IDS

No signature in packet => “per packet” approaches

Extract the essential signature of attack traffic

Small average throughput => Throughput based IDS

No signature in packet => “per packet” approaches

Extract the essential signature of attack traffic

X

X

√√

Page 14: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.15.

Pattern

match

Pattern

matchPattern

match

Pattern

matchExtract the

signature

Extract the

signatureExtract the

signature

Extract the

signatureFilter the

noise

Filter the

noiseFilter the

noise

Filter the

noiseSample

the traffic

Sample

the trafficSample

the traffic

Sample

the traffic

Algorithm of Detection

Sample the throughput of link interface at a

constant rate(The rate should be frequent enough but not over burden

system)

Each time of detection consists of a sequence of

sampled throughput(The length of sequence should also be properly adjusted)

Normalization is necessary

Normalized _Throughput =Instantaneous_ throughput

Maximum _ link _bandwidth

The background noise of samples need to be filtered

Background noise(UDP flows and other TCP flows that less sensitive to attack)

For simplicity, a threshold filter can be used.

Autocorrelation is adopted to extract the periodic signature of input signal.periodic input => special pattern of its autocorrelation.Autocorrelation can also mask the difference of time shift SUnbiased normalizationM: length of input sequencem: index of autocorrelation

n

mM

nnmx XX

mMmA ×

−= ∑

+−

=+

1

0

1)(

)min(),(1∑=

=K

kkwInputTemplateDTW

Similarity between the template and input should

be calculated.

We use Dynamic Time Warping (DTW).

(The detail algorithm of DTW is provided in the paper)

The smaller the DTW value is, the more similar

they are.

DTW values will clustered; threshold can be set to

distinguish them.

Page 15: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.16.

Robustness of Detection

DTW Value

0

5

10

15

20

25

30

35

40

0 2000 4000 6000 8000 10000 12000

  SPSB RPSB SPGB RPGB

Max 34.88 35.66 34.08 34.69

Min 0 0.80 0.84 1.20

Mean 10.68 9.63 10.89 10.48

Stdv 7.83 6.86 6.77 5.26

Attack traffic simulations DTW values for low-rate attack

4 types of attack traffic:

Strictly Periodic Square Burst (SPSB),

Random Periodic Square Burst (RPSB),

Strictly Periodic General Burst (SPGB),

Random Periodic General Burst (RPGB) T ,l : Uniformly distributed s.t. :l /T<=0.25 R : 1 (full bandwidth)N,S : Uniformly distributedAround 3000 simulations /type

4 types of attack traffic:

Strictly Periodic Square Burst (SPSB),

Random Periodic Square Burst (RPSB),

Strictly Periodic General Burst (SPGB),

Random Periodic General Burst (RPGB) T ,l : Uniformly distributed s.t. :l /T<=0.25 R : 1 (full bandwidth)N,S : Uniformly distributedAround 3000 simulations /type

Page 16: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.17.

Robustness of Detection

DTW values of legitimate trafficLegitimate traffic composition.Legitimate traffic simulation using

Gaussian model:

C+ Gaussian(0, N)Run more than 8000 simulations

DTW values of legitimate trafficLegitimate traffic composition.Legitimate traffic simulation using

Gaussian model:

C+ Gaussian(0, N)Run more than 8000 simulations

Max286.

53

Min113.

50

Mean236.

95

Stdv43.1

0

DTW values for Legitimate traffic

(Gaussian)

Page 17: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.18.

Attack flows V.S.

legitimate

(Gaussian) flows

Expect a

separation between

them.

Attack flows V.S.

legitimate

(Gaussian) flows

Expect a

separation between

them.

Robustness of Detection

Probability distribution of DTW values

Page 18: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.19.

Robustness of Detection

More accurate network traffic model

(Ethernet traffic, WWW traffic) Use FARIMA model to generate self-

similar traffic.Hurst Parameter H: [0.75-0.85] Run more than 10,000 simulations

More accurate network traffic model

(Ethernet traffic, WWW traffic) Use FARIMA model to generate self-

similar traffic.Hurst Parameter H: [0.75-0.85] Run more than 10,000 simulations

Max238.

16

Min28.0

1

Mean130.

73

Stdv51.4

4

DTW values for Legitimate traffic (Self-similar)

Page 19: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.20.

Attack flows V.S.

Self-similar flows

Small Overlap

(Around 30)

Attack flows V.S.

Self-similar flows

Small Overlap

(Around 30)

Robustness of DetectionProbability distribution of DTW values (Self-similar)

False Self-similar 141

Total Self-similar

11000

False Positive

1.28%

False Attack 378

Total Attack1149

2

False Negative

3.54%

Page 20: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.21.

What is the next?

Introduction to Low-rate TCP Attack Formal Description of Low-rate TCP AttackDistributed Dynamic Detection Low-rate Attack Defense Mechanism Fluid Model of TCP FlowsDefence ExperimentsRelated Work & Conclusion

Page 21: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.22.

Pushback detection Pushback to

outmost deployed router

distributed attackDeficit Round Robin (DRR)

Pushback detection Pushback to

outmost deployed router

distributed attackDeficit Round Robin (DRR)

Defense Mechanism

Router deployment

}Resource Management

Page 22: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.23.

Deficit Round Robin (DRR)

Defense Mechanism

1500

300

600 600

500

2000 1000

SecondRound

FirstRound

Head ofQueue

A

B

C

0

Quantum[i]=1000 bytes 1st Round

A’s counter : 1000

B’s counter : 200 (served twice)

C’s counter : 400

2nd Round

A’s counter: 500 (served)

B’s counter: 0

C’s counter: 800 (served)

Classify packets according to the input port [i].deficit_counter[i]=0 ; deficit_counter[i] += Quantum[i] If packet’s size<= deficit_counter[i] , serve the packetdeficit_counter[i] -=packet’s size.If no packet[i], deficit_counter[i] =0.

Classify packets according to the input port [i].deficit_counter[i]=0 ; deficit_counter[i] += Quantum[i] If packet’s size<= deficit_counter[i] , serve the packetdeficit_counter[i] -=packet’s size.If no packet[i], deficit_counter[i] =0.

Page 23: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.24.

Definitions in DRR algorithm

Fairness Analysis of DRR Algorithm

Backlogged:A port i is backlogged during an interval (t1; t2)

of a DRR execution if the queue for port i is never empty durin

g the interval.

Flow Share: We assume there is some quantity fi that expresses the ideal share obtained by the port i that

fi = Quantum[i]/Quantum where Quantum = Min(Quantum[i]).

Sent Packets: Let senti(t1; t2) be the total number of bytes se

nt on the output port i in the interval (t1; t2)

Backlogged:A port i is backlogged during an interval (t1; t2)

of a DRR execution if the queue for port i is never empty durin

g the interval.

Flow Share: We assume there is some quantity fi that expresses the ideal share obtained by the port i that

fi = Quantum[i]/Quantum where Quantum = Min(Quantum[i]).

Sent Packets: Let senti(t1; t2) be the total number of bytes se

nt on the output port i in the interval (t1; t2)

Fairness Measurement: Let Fairness Measurement

FM(t1; t2) be the maximum of (senti(t1; t2)/fi - sentj(t1; t2)/fj)

over all ports i,j that are backlogged in the interval (t1; t2).

Now we can define a service discipline to be fair if FM(t1; t2)

is bounded by a small constant.

Fairness Measurement: Let Fairness Measurement

FM(t1; t2) be the maximum of (senti(t1; t2)/fi - sentj(t1; t2)/fj)

over all ports i,j that are backlogged in the interval (t1; t2).

Now we can define a service discipline to be fair if FM(t1; t2)

is bounded by a small constant.

Page 24: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.25.

Lemmas of DRR Fairness

Fairness Analysis of DRR Algorithm

Lemma 1: For any port i ,during the execution of DRR

algorithm, the deficit_counter[i] is within the range [0;Max) at

the end of each round, where Max is the maximum size of all

possible packets.

0 ≤deficit_counter[i] < Max Proof: Initially deficit_counter[i] = 0. After queue i is serviced in each round: 1) If there are packet(s) left in the queue for port i 0 ≤deficit_counter[i] < Max 2) If no packets are left in the queue deficit_counter[i] is reset to zero

Lemma 1: For any port i ,during the execution of DRR

algorithm, the deficit_counter[i] is within the range [0;Max) at

the end of each round, where Max is the maximum size of all

possible packets.

0 ≤deficit_counter[i] < Max Proof: Initially deficit_counter[i] = 0. After queue i is serviced in each round: 1) If there are packet(s) left in the queue for port i 0 ≤deficit_counter[i] < Max 2) If no packets are left in the queue deficit_counter[i] is reset to zero

Page 25: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.26.

Proof: Let deficit_counter[i][k] be the value of deficit_counter[i] at the end of k round DRR executions. Let bytesi(k) be the bytes sent by port i in round k.

And let senti(k) be the bytes sent by port i from round 1 through k.Thus, senti(k) = ∑ bytesi(k)

Obviously: bytesi(k)+deficit_counter[i][k] = Quantum[i]+deficit_counter[i][k-1]

bytesi(k)= Quantum[i]+deficit_counter[i][k-1]- deficit_counter[i][k]

Proof: Let deficit_counter[i][k] be the value of deficit_counter[i] at the end of k round DRR executions. Let bytesi(k) be the bytes sent by port i in round k.

And let senti(k) be the bytes sent by port i from round 1 through k.Thus, senti(k) = ∑ bytesi(k)

Obviously: bytesi(k)+deficit_counter[i][k] = Quantum[i]+deficit_counter[i][k-1]

bytesi(k)= Quantum[i]+deficit_counter[i][k-1]- deficit_counter[i][k]

Lemmas of DRR Fairness

Summing this equation over m rounds of servicing of port i: We have:

senti(m) = m×Quantum[i] + deficit_counter[i][0] – deficit_counter[i][m]

Since deficit_counter[i] is always non negative and upper bounded by Max (Lemma1), the result follows.

Summing this equation over m rounds of servicing of port i: We have:

senti(m) = m×Quantum[i] + deficit_counter[i][0] – deficit_counter[i][m]

Since deficit_counter[i] is always non negative and upper bounded by Max (Lemma1), the result follows.

Fairness Analysis of DRR Algorithm

Lemma 2: m×Quantum[i]-Max ≤ senti(t1; t2) ≤ m×Quantum[i] +Max

Lemma 2: m×Quantum[i]-Max ≤ senti(t1; t2) ≤ m×Quantum[i] +Max

Lemma 2: During any period in which port i is backlogged

the number of bytes sent on the behalf of port i is roughly equal

to m×Quantum[i] ,specifically bounded as follows:

m×Quantum[i]-Max ≤ senti(t1; t2) ≤ m×Quantum[i] +Max where m is the number of round-robin service round received

by port i during this interval.

Lemma 2: During any period in which port i is backlogged

the number of bytes sent on the behalf of port i is roughly equal

to m×Quantum[i] ,specifically bounded as follows:

m×Quantum[i]-Max ≤ senti(t1; t2) ≤ m×Quantum[i] +Max where m is the number of round-robin service round received

by port i during this interval.

Page 26: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.27.

Theorem of DRR Fairness

Fairness Analysis of DRR Algorithm

Theorem 1: For an interval (t1; t2) in any execution of the

DRR service discipline

FM(t1; t2) ≤ 2×Max + Quantum;

where Quantum = Min(Quantum[i])

Theorem 1: For an interval (t1; t2) in any execution of the

DRR service discipline

FM(t1; t2) ≤ 2×Max + Quantum;

where Quantum = Min(Quantum[i])

Proof:

let m be the number of DRR execution rounds given to port i in interval (t1; t2),

let m’ be the number of DRR execution rounds given to port j in the same interval.

As each class is serviced in a strict round-robin mode, then: | m – m’ | ≤ 1

Proof:

let m be the number of DRR execution rounds given to port i in interval (t1; t2),

let m’ be the number of DRR execution rounds given to port j in the same interval.

As each class is serviced in a strict round-robin mode, then: | m – m’ | ≤ 1

From Lemma 2: senti(t1; t2) ≤ m×Quantum[i] +Max since Ideal Share fi = Quantum[i]/Quantum We have the normalized service received by port i: senti(t1; t2)/fi ≤ m×Quantum + Max/fi (1)

Similarly for port j: sentj(t1; t2)/fj ≥ m’×Quantum - Max/fj (2)

From Lemma 2: senti(t1; t2) ≤ m×Quantum[i] +Max since Ideal Share fi = Quantum[i]/Quantum We have the normalized service received by port i: senti(t1; t2)/fi ≤ m×Quantum + Max/fi (1)

Similarly for port j: sentj(t1; t2)/fj ≥ m’×Quantum - Max/fj (2)

Thus: FM(t1; t2) = senti(t1; t2)/fi- sentj(t1; t2)/fj

≤ (m-m’) ×Quantum + Max/fi + Max/fj

≤ Quantum+2Max ■

Thus: FM(t1; t2) = senti(t1; t2)/fi- sentj(t1; t2)/fj

≤ (m-m’) ×Quantum + Max/fi + Max/fj

≤ Quantum+2Max ■

Page 27: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.28.

Analytical Results for DRR Algorithm

Analysis of DRR Algorithm

Fairness: Using Golestani's fairness definition, difference in

the normalized bytes sent between ports within a certain interv

al (t1; t2) is bounded by a small constant.

Implementation Cost: DRR algorithm can be implemente

d with less work compared with other scheduling algorithm.

In general, the processing cost of DRR is O(1) per packet.

As a result, DRR can provide not only a fairness scheduling

method, but also work with a low implementation cost.

Fairness: Using Golestani's fairness definition, difference in

the normalized bytes sent between ports within a certain interv

al (t1; t2) is bounded by a small constant.

Implementation Cost: DRR algorithm can be implemente

d with less work compared with other scheduling algorithm.

In general, the processing cost of DRR is O(1) per packet.

As a result, DRR can provide not only a fairness scheduling

method, but also work with a low implementation cost.

Page 28: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.29.

What is the next?

Introduction to Low-rate TCP Attack Formal Description of Low-rate TCP AttackDistributed Dynamic Detection Low-rate Attack Defense Mechanism Fluid Model of TCP FlowsDefence ExperimentsRelated Work & Conclusion

Page 29: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.30.

In a Congested Droptail Router:1. N TCP flows go through

2. Droptail queue at output interface Dropping Function:

P: Drop Prob. xi: length of queue i; Qi: Size of queue i

Behavior of Queue Length: C: Capacity of the link

In a Congested Droptail Router:1. N TCP flows go through

2. Droptail queue at output interface Dropping Function:

P: Drop Prob. xi: length of queue i; Qi: Size of queue i

Behavior of Queue Length: C: Capacity of the link

Model of TCP on a Droptail Router

Fluid Model of TCP Flows

⎩⎨⎧

>≤

= )1(,1

,0)(

ii

iii

Qx

Qxxp

)2(1))]((1[)( )(

1

Ctxptdt

dxtxi

N

i

ii

i−−×=∑−

ρ

Page 30: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.31.

Throughput of TCP flow i:Wi(t) :Window Size

Ri(t) : Round Trip Time

Round Trip Time:

ai :Propagation delay

Throughput of TCP flow i:Wi(t) :Window Size

Ri(t) : Round Trip Time

Round Trip Time:

ai :Propagation delay

Model of TCP on a Droptail Router

Fluid Model of TCP Flows

)3()(

)()(

tR

tWt

i

ii =ρ

)4()(

)(C

txatR

iii +=

Page 31: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.32.

Slow start/ Congestion Avoidance: Hi :threshold

Retransmission Time Out:

where u(n) is a unit step function:

q(W) denotes the Prob. of that loss is caused by timeout

Slow start/ Congestion Avoidance: Hi :threshold

Retransmission Time Out:

where u(n) is a unit step function:

q(W) denotes the Prob. of that loss is caused by timeout

Model of TCP on a Droptail Router

Fluid Model of TCP Flows

)5())'((2

)())]'((1[)'()( ttxp

tWttxpttHtH i

iiii −+−−×−=

)6())](1([))(())'(())(()(

tTtutWqttxptTtdt

tdTiii

i+−××−×−=

)7(0,1

0,0)(

⎩⎨⎧

≥<

=i

ii

nn

nu

)8())(

3,1())((

tWMintWq

ii =

Finally, the behavior of TCP window size:

Overview of TCP droptail scheduling:

Numerical result of differential equations (1-9)

Finally, the behavior of TCP window size:

Overview of TCP droptail scheduling:

Numerical result of differential equations (1-9)

))'(()'(

)'()1)((

)9())'(()'(2

)'()](1[

)]1([])[1

][(

ttxpttR

ttWWWq

ttxpttR

ttWWWq

TtuHWuR

WHuR

W

dt

dW

ii

iii

ii

ii

iiii

iii

ii

i

−−−

−−

−−−×

−−

+−×−+−=

Page 32: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.33.

Modification based on the Droptail Model Different Queue Management may cause:

1. Change of the behavior of Queue Length

2. Change of the calculation of round trip time

Modification based on the Droptail Model Different Queue Management may cause:

1. Change of the behavior of Queue Length

2. Change of the calculation of round trip time

Model of TCP on a DRR Router

Fluid Model of TCP Flows

Behavior of Queue Length in DRR:

where τt : time length for each round

Behavior of Queue Length in DRR:

where τt : time length for each round

)10())(,(

1))]((1[)( )(t

iitxii

i txQuantumMintxpt

dt

dxi τρ −−×=

)11())(,(

C

txQuantumMinN

i

ii

t

∑=τ

Calculation of round trip time :

Fluid Model of TCP on DRR router: Replace the corresponding two equations in Droptail Model

Calculation of round trip time :

Fluid Model of TCP on DRR router: Replace the corresponding two equations in Droptail Model

)12()(

)(C

txNatR

iii

×+=

Page 33: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.34.

Attack with Single TCP Flow

(Droptail Router):Settings:

T = 1.1s,l = 0.1s R = 300kb/sC = 100kb/s Propagation delay=0.1s

Attack starts 2s later

Attack with Single TCP Flow

(Droptail Router):Settings:

T = 1.1s,l = 0.1s R = 300kb/sC = 100kb/s Propagation delay=0.1s

Attack starts 2s later

Simulation of TCP fluid model

Fluid Model of TCP Flows

Droptail Queue

Attack

TCP

Page 34: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.35.

Attack with Single TCP Flow

(DRR Router):Settings:

T = 1.1s,l = 0.1s R = 300kb/sC = 100kb/s Propagation delay=0.1sQuantum = 1kb Buffer size =10kbAttack starts 2s later

Attack with Single TCP Flow

(DRR Router):Settings:

T = 1.1s,l = 0.1s R = 300kb/sC = 100kb/s Propagation delay=0.1sQuantum = 1kb Buffer size =10kbAttack starts 2s later

Simulation of TCP fluid model

Fluid Model of TCP Flows

Attack

TCP

DRR Queues

Page 35: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.36.

Attack with Multiple TCP Flows

(Droptail Router):

Settings:

T = 1.1s,l = 0.1s R = 300kb/sC = 100kb/s Attack starts 2s laterPropagation delay=0.1s, 0.2s, 0.4s and 0.8s

Attack with Multiple TCP Flows

(Droptail Router):

Settings:

T = 1.1s,l = 0.1s R = 300kb/sC = 100kb/s Attack starts 2s laterPropagation delay=0.1s, 0.2s, 0.4s and 0.8s

Simulation of TCP fluid model

Fluid Model of TCP Flows

TCP1

Attack

TCP2

TCP3

TCP4

Droptail Queue

Page 36: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.37.

Attack with Multiple TCP Flows

(DRR Router):Settings:

T = 1.1s,l = 0.1s R = 300kb/sC = 100kb/s Quantum = 1kb Buffer size =10kbAttack starts 2s laterPropagation delay=0.1s, 0.2s, 0.4s and 0.8s

Attack with Multiple TCP Flows

(DRR Router):Settings:

T = 1.1s,l = 0.1s R = 300kb/sC = 100kb/s Quantum = 1kb Buffer size =10kbAttack starts 2s laterPropagation delay=0.1s, 0.2s, 0.4s and 0.8s

Simulation of TCP fluid model

Fluid Model of TCP Flows

Attack

TCP1

DRR Queues

TCP2

TCP3

TCP4

Page 37: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.38.

What is the next?

Introduction to Low-rate TCP Attack Formal Description of Low-rate TCP AttackDistributed Dynamic Detection Low-rate Attack Defense Mechanism Fluid Model of TCP FlowsDefence ExperimentsRelated Work & Conclusion

Page 38: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.39.

Experiment of Defense Mechanism

Single TCP flow vs. single source attacker

Go through the

same router Link Capacity

5Mbp/s

Go through the

same router Link Capacity

5Mbp/s

  Drop Tail DRR

  TCP (Kbps) Attack (Kbps) TCP (Kbps) Attack (Kbps)

Tahoe224.3

74.49

%1016.

5220.33

%3402.

0768.04

%780.3

915.61

%

Reno 26.300.53

%1022.

5520.45

%946.8

718.94

%1014.

9720.30

%

NewReno 23.62

0.47%

1022.04

20.44%

3690.32

73.81%

913.39

18.27%

Page 39: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.40.

Experiment of Defense Mechanism

Multiple TCP flows vs. single source attacker  Drop Tail DRR

  Throughput (Kbps)

% of link capacityThroughput (Kbps)

% of link capacity

Attack 928.76 18.58% 343.09 6.86%

TCP1 8.71 0.17% 965.91 19.32%

TCP2 210.77 4.22% 645.79 12.92%

TCP3 4.75 0.10% 629.15 12.58%

TCP4 11.09 0.22% 618.05 12.36%

TCP5 5.54 0.11% 468.3 9.37%

TCP6 267.82 5.36% 356.57 7.13%

TCP7 72.11 1.44% 293.97 5.88%

TCP8 3.17 0.06% 194.93 3.90%

TCP Sum

583.96 11.68% 4172.67 83.45%

Eight TCP flowsSingle low-rate

attackerGo through the

same router Link Capacity

5Mbp/s

Eight TCP flowsSingle low-rate

attackerGo through the

same router Link Capacity

5Mbp/s

Page 40: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.41.

Experiment of Defense MechanismNetwork model of attack vs. Multiple TCP flows   Drop Tail DRR on R6

DRR on R6,R4

DRR on R6,R4,R2

DRR on R6,R4,R2,R

1

  ρ(Kbps) ρ(Kbps) ρ(Kbps) ρ(Kbps) ρ(Kbps)

Attack 640.00 561.00 453.00 419.00 404.00

TCP1 386.00 358.00 311.00 314.00 778.00

TCP2 264.00 329.00 282.00 874.00 763.00

TCP3 324.00 251.00 1245.00 924.00 788.00

TCP4 425.00 1719.00 1154.00 966.00 765.00

Total TCP 1399.00 2657.00 2992.00 3078.00 3094.00

4 TCP flows Single attacker7 routers network R1,R2,R4,R6 may

run DRRLink capacity 5 Mb/s

4 TCP flows Single attacker7 routers network R1,R2,R4,R6 may

run DRRLink capacity 5 Mb/s

Page 41: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.42.

What is the next?

Introduction to Low-rate TCP Attack Formal Description of Low-rate TCP AttackDistributed Dynamic Detection Low-rate Attack Defense Mechanism Fluid Model of TCP FlowsDefence ExperimentsRelated Work & Conclusion

Page 42: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.43.

Related Work & Conclusion

Related Work

Another solution to this attack:

Randomizing RTO 1. Intuitive solution

2. Widespread updates of end user software3. May reduce the performance of TCP

Reduction of Quality (RoQ) Attack1. General class of attack exploiting the transi

ents of adaptation.

2. Similar attack form

Another solution to this attack:

Randomizing RTO 1. Intuitive solution

2. Widespread updates of end user software3. May reduce the performance of TCP

Reduction of Quality (RoQ) Attack1. General class of attack exploiting the transi

ents of adaptation.

2. Similar attack form

Conclusions

Formal model to describe low-rate TCP attack.

Distributed detection mechanism using

Dynamic Time Wrapping

The push back mechanism

DRR approach protection and isolation

Formal model to describe low-rate TCP attack.

Distributed detection mechanism using

Dynamic Time Wrapping

The push back mechanism

DRR approach protection and isolation

Page 43: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.44.

Major References

HaiBin Sun, John C.S. Lui, David K.Y. Yau. “Defending Against Low-rate TCP Attack: Dynamic Detection and Protection” IEEE International Conference on Network Protocols (ICNP), Berlin, Germany, October, 2004.

HaiBin Sun, John C.S. Lui, David K.Y. Yau. “Distributed Mechanism in Detecting and Defending Against Low-rate TCP Attack” Computer Networks Journal (Elsevier), July,2005.

Page 44: Defending Against Low-rate TCP Attack: Dynamic Detection and Protection

.45.

Thank you for your attention!

Q & A


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