09-Security Configuration Examples

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06-H3C_Attack_Protection_Configuration_Examples
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H3C Attack Protection Configuration Examples

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Software version: Release 7595

Document version: 6W100-20201031

 

Copyright © 2020 New H3C Technologies Co., Ltd. All rights reserved.

No part of this manual may be reproduced or transmitted in any form or by any means without prior written consent of New H3C Technologies Co., Ltd.

Except for the trademarks of New H3C Technologies Co., Ltd., any trademarks that may be mentioned in this document are the property of their respective owners.

The information in this document is subject to change without notice.



Introduction

This document provides configuration examples of link layer attack protection, ARP attack protection, network layer attack protection, and transport layer attack protection, as defined in Table 1.

Table 1 Attack protection types

Attack protection types

Description

Link layer attack protection

MAC address attack protection

Prevents the attack of packets with different source MAC addresses or VLANs by configuring the maximum number of MAC addresses that an interface can learn.

STP packet attack protection

Provides protection measures such as BPDU guard, root guard, loop guard, and TC-BPDU guard.

ARP attack protection

ARP source suppression

Prevents IP attack packets from fixed sources.

ARP black hole routing

Prevents IP attack packets from sources that are not fixed.

ARP active acknowledgement

Prevents user spoofing.

Source MAC-based ARP attack detection

Prevents ARP packet attacks from the same source MAC.

ARP packet source MAC consistency check

Prevents attacks from ARP packets whose source MAC address in the Ethernet header is different from the sender MAC address in the message body.

Network layer attack protection

uRPF check

Protects a network against source spoofing attacks.

TTL attack protection

Prevents an attack by disabling sending ICMP time exceeded messages.

Transport layer attack protection

SYN flood attack protection

Enables the server to return a SYN ACK message when it receives a TCP connection request, without establishing a half-open TCP connection.

 

Prerequisites

The configuration examples in this document were created and verified in a lab environment, and all the devices were started with the factory default configuration. When you are working on a live network, make sure you understand the potential impact of every command on your network.

This document assumes that you have basic knowledge of attack protection.

Example: Configuring link layer attack protection

Network configuration

As shown in Figure 1, Device A, Device B, and Device C run MSTP. Device B acts as the root bridge, and Ten-GigabitEthernet 1/0/1 on Device C is blocked.

Configure the following features to prevent link layer attacks:

·     Configure root guard on Ten-GigabitEthernet 1/0/1 and Ten-GigabitEthernet 1/0/2 of Device B for Device B to act as the root bridge.

·     Configure loop guard on Ten-GigabitEthernet 1/0/2 of Device C to prevent temporary loops. The loop guard feature keeps the port in Discarding state in all MSTIs when it receives no BPDU.

·     Configure BPDU guard on ports at the access side of Device A and Device C. The BPDU guard feature prevents the ports from performing spanning tree calculations when it receives forged BPDUs with a higher priority.

·     Enable TC-BPDU guard on Device A, Device B, and Device C. The TC-BPDU guard feature prevents a large number of TC-BPDUs from affecting the network in a short time.

·     Set the maximum number of MAC addresses that can be learned by ports at the access side of Device A and Device C. This configuration protects the devices from a large number of attack packets that have different source MAC addresses. The attack packets might cause a large MAC table and low forwarding performance.

·     Configure broadcast and multicast suppression on the designated ports of Device B and all ports on Device A and Device C. When incoming broadcast or multicast traffic exceeds the threshold, an interface discards broadcast or multicast packets until the traffic drops below the threshold.

Figure 1 Network diagram

 

Analysis

For the ports at the access side of Device A and Device C to rapidly transit to the forwarding state, use the stp edged-port command to configure these ports as edge ports.

This example uses Ten-GigabitEthernet 1/0/3 to illustrate the configuration on the ports at the access side on Device A and Device C.

Restrictions and guidelines

When you configure link layer attack protection, follow these restrictions and guidelines:

·     On a port, the loop guard feature is mutually exclusive with the root guard feature or the edge port setting.

·     Do not configure the loop guard feature on ports at the access side. Otherwise, the ports stay in Discarding state in all MSTIs because they cannot receive BPDUs.

Procedures

Configuring Device B

# Specify IP addresses for interfaces. (Details not shown.)

# Configure root guard on Ten-GigabitEthernet 1/0/1 and Ten-GigabitEthernet 1/0/2.

<DeviceB> system-view

[DeviceB] interface range Ten-GigabitEthernet 1/0/1 to Ten-GigabitEthernet 1/0/2

[DeviceB-if-range] stp root-protection

[DeviceB-if-range] quit

# Configure TC-BPDU guard.

[DeviceB] stp tc-protection

[DeviceB] stp tc-protection threshold 10

# Configure broadcast and multicast suppression on Ten-GigabitEthernet 1/0/1 and Ten-GigabitEthernet 1/0/2.

[DeviceB] interface range Ten-GigabitEthernet 1/0/1 to Ten-GigabitEthernet 1/0/2

[DeviceB-if-range] broadcast-suppression pps 6400

[DeviceB-if-range] multicast-suppression pps 6400

[DeviceB-if-range] quit

Configuring Device A

# Specify IP addresses for interfaces. (Details not shown.)

# Configure STP BPDU guard.

<DeviceA> system-view

[DeviceA] stp bpdu-protection

# Configure Ten-GigabitEthernet 1/0/3 as an edge port.

[DeviceA] interface Ten-GigabitEthernet 1/0/3

[DeviceA-Ten-GigabitEthernet1/0/3] stp edged-port

[DeviceA-Ten-GigabitEthernet1/0/3] quit

# Configure TC-BPDU guard.

[DeviceA] stp tc-protection

[DeviceA] stp tc-protection threshold 10

# Set the maximum number of MAC addresses that Ten-GigabitEthernet 1/0/3 can learn.

[DeviceA] interface Ten-GigabitEthernet 1/0/3

[DeviceA-Ten-GigabitEthernet1/0/3] mac-address max-mac-count 1024

[DeviceA-Ten-GigabitEthernet1/0/3] quit

# Configure broadcast and multicast suppression on all ports.

[DeviceA] interface range Ten-GigabitEthernet 1/0/1 to Ten-GigabitEthernet 1/0/3

[DeviceA-if-range] broadcast-suppression pps 6400

[DeviceA-if-range] multicast-suppression pps 6400

[DeviceA-if-range] quit

Configuring Device C

# Specify IP addresses for interfaces. (Details not shown.)

# Configure STP BPDU guard.

<DeviceC> system-view

[DeviceC] stp bpdu-protection

# Configure Ten-GigabitEthernet 1/0/3 as an edge port.

[DeviceC] interface Ten-GigabitEthernet 1/0/3

[DeviceC-Ten-GigabitEthernet1/0/3] stp edged-port

[DeviceC-Ten-GigabitEthernet1/0/3] quit

# Configure root guard on Ten-GigabitEthernet 1/0/1.

[DeviceC] interface Ten-GigabitEthernet 1/0/1

[DeviceC-Ten-GigabitEthernet1/0/1] stp root-protection

[DeviceC-Ten-GigabitEthernet1/0/1] quit

# Configure loop guard on Ten-GigabitEthernet 1/0/2.

[DeviceC] interface Ten-GigabitEthernet 1/0/2

[DeviceC-Ten-GigabitEthernet1/0/2] stp loop-protection

[DeviceC-Ten-GigabitEthernet1/0/2] quit

# Configure TC-BPDU guard.

[DeviceC] stp tc-protection

[DeviceC] stp tc-protection threshold 10

# Set the maximum number of MAC addresses that Ten-GigabitEthernet 1/0/3 can learn.

[DeviceC] interface Ten-GigabitEthernet 1/0/3

[DeviceC-Ten-GigabitEthernet1/0/3] mac-address max-mac-count 1024

[DeviceC-Ten-GigabitEthernet1/0/3] quit

# Configure broadcast and multicast suppression on all ports.

[DeviceC] interface range Ten-GigabitEthernet 1/0/1 to Ten-GigabitEthernet 1/0/3

[DeviceC-if-range] broadcast-suppression pps 6400

[DeviceC-if-range] multicast-suppression pps 6400

[DeviceC-if-range] quit

Verifying the configuration

# Verify that the edge ports go down after they receives STP BPDUs. (Details not shown.)

# Bring the edge ports up by using the undo shutdown command. (Details not shown.)

# Verify that the root ports do not change and that the STP topology remains stable after STP BPDUs with higher priority are sent to the designated ports. (Details not shown.)

# Verify that the devices do not refresh the FIB table frequently and that no serious packet loss occurs after a large number of various TC BPDUs are sent to the devices. (Details not shown.)

# Verify that the uplink ports are not flooded after a large number of broadcasts are sent to the edge ports on device A and Device C. (Details not shown.)

Configuration files

·     Device A:

#

stp bpdu-protection

stp tc-protection

stp tc-protection threshold 10

#

interface Ten-GigabitEthernet 1/0/1

 port link-mode bridge   

broadcast-suppression pps 6400

 multicast-suppression pps 6400

#

interface Ten-GigabitEthernet 1/0/2

port link-mode bridge   

broadcast-suppression pps 6400

multicast-suppression pps 6400

#

interface Ten-GigabitEthernet 1/0/3

 port link-mode bridge   

mac-address max-mac-count 1024

 stp edged-port

 broadcast-suppression pps 6400

multicast-suppression pps 6400

#

·     Device B:

#

stp tc-protection

stp tc-protection threshold 10

#

 interface Ten-GigabitEthernet 1/0/1

port link-mode bridge      

stp root-protection

broadcast-suppression pps 6400

multicast-suppression pps 6400

#

 interface Ten-GigabitEthernet 1/0/2

  port link-mode bridge   

stp root-protection

  broadcast-suppression pps 6400

multicast-suppression pps 6400

#

interface Ten-GigabitEthernet 1/0/3

port link-mode bridge   

stp edged-port

#

·     Device C:

#

stp bpdu-protection

stp tc-protection

stp tc-protection threshold 10

#

interface Ten-GigabitEthernet 1/0/1

port link-mode bridge   

stp root-protection

broadcast-suppression pps 6400

multicast-suppression pps 6400

#

interface Ten-GigabitEthernet 1/0/2

port link-mode bridge   

stp loop-protection

broadcast-suppression pps 6400

multicast-suppression pps 6400

#

interface Ten-GigabitEthernet 1/0/3

port link-mode bridge   

 mac-address max-mac-count 1024

broadcast-suppression pps 6400

multicast-suppression pps 6400

#

Example: Configuring ARP attack protection

Network configuration

As shown in Figure 2, the device is the gateway for the internal network. Configure ARP attack protection on the device to prevent ARP attacks.

Figure 2 Network diagram

 

Procedures

# Specify IP addresses for interfaces. (Details not shown.)

# Enable ARP source suppression.

<Device> system-view

[Device] arp source-suppression enable

# Configure the device to accept a maximum of 8 unresolvable packets per source IP address in 5 seconds.

[Device] arp source-suppression limit 8

# Enable ARP black hole routing to prevent unresolvable IP packet attacks.

[Device] arp resolving-route enable

# Enable ARP active acknowledgment to prevent user spoofing.

[Device] arp active-ack enable

# Configure source MAC-based ARP attack detection to prevent ARP packet attacks from the same source MAC.

[Device] arp source-mac filter

[Device] arp source-mac threshold 25

# Enable ARP packet source MAC address consistency check to prevent attacks from ARP packets with different source MAC addresses in the Ethernet header and in the message body.

[Device] arp valid-check enable

Verifying the configuration

1.     Verify that ARP attack protection functions on the device:

# Send ARP attack packets to the device. (Details not shown.)

# Verify that the CPU usage does not surge. (Details not shown.)

2.     Verify that each ARP attack protection feature functions on the device (this example uses the ARP source suppression feature):

# Send the device 20 forged packets with the same source IP address and unresolvable destination IP addresses. (Details not shown.)

# Verify that the device stops resolving the packets after receiving 8 forged packets within 5 seconds. (Details not shown.)

# Verify the ARP source suppression configuration.

<Sysname> display arp source-suppression

 ARP source suppression is enabled

 Current suppression limit: 8

Configuration files

#

 arp valid-check enable

 arp source-mac filter

 arp source-mac threshold 25

 arp active-ack enable

 arp source-suppression enable

 arp source-suppression limit 8

#

Example: Configuring network layer attack protection

Network configuration

As shown in Figure 3, Device A is the gateway for the internal network. To protect Device A against IP packet attacks from internal and external networks, configure the following network layer attack protection features:

·     Configure strict uRPF check to prevent source address spoofing attacks.

·     Disabling sending ICMP time exceeded messages. The device will not be flooded by ICMP time exceeded messages when receiving a large number of packets in which the TTL is 1.

Figure 3 Network diagram

 

Restrictions and guidelines

After you disable sending ICMP time exceeded messages, the traceroute feature will not be available.

Procedures

# Specify IP addresses for interfaces. (Details not shown.)

# Enable strict uRPF check.

[DeviceA] ip urpf strict

# Disable sending ICMP time exceeded messages. Sending ICMP time exceeded messages is disabled by default.

[DeviceA] undo ip ttl-expires enable

Verifying the configuration

1.     Verify that Device A can prevent source address spoofing attacks:

# Verify that Device A can filter out packets with forged source IP addresses. (Details not shown.)

# Verify the uRPF configuration.

<DeviceA> display ip urpf

Global uRPF configuration information:

   Check type: strict  

2.     Verify that TTL attack protection functions on Device A:

# Enable ICMP debugging by executing the debugging ip icmp command on Device A. (Details not shown.)

# Use a PC to send packets in which the TTL is 1 to Device A. (Details not shown.)

# Verify that Device A does not display any debugging information and that the PC does not receive any ICMP time exceeded messages. (Details not shown.)

# Enable sending ICMP time exceeded messages and send packets in which the TTL is 1 to Device A. (Details not shown.)

# Verify that Device A responds with ICMP time exceeded messages.

<DeviceA> *Aug 14 16:43:31:068 2020 NM-3 SOCKET/7/ICMP: -MDC=1-Slot=2;

Time(s):1371221011  ICMP Output:

 ICMP Packet: src = 6.0.0.1, dst = 202.101.0.2

              type = 11, code = 0 (ttl-exceeded)

 Original IP: src = 202.101.0.2, dst = 192.168.0.2

              proto = 253, first 8 bytes = 00000000 00000000

Configuration files

#

ip urpf strict

#

Example: Configuring transport layer attack protection

Network configuration

As shown in Figure 4, the device is the gateway for the internal network. Configure SYN Cookie protection on the device to protect against SYN flood attacks. With this feature enabled, the device responds to a SYN packet with a SYN ACK packet without establishing a TCP semi-connection. The device establishes a TCP connection only when it receives an ACK packet from the sender.

Figure 4 Network diagram

 

Procedures

# Specify IP addresses for interfaces. (Details not shown.)

# Enable SYN Cookie.

<Device> system-view

[Device] tcp syn-cookie enable

Verifying the configuration

# Verify that the device does not have any TCP semi-connections. The state "SYN_RECEIVED" represents semi-connections.

[Device] display tcp

 *: TCP Connection with authentication

 Local Addr:port       Foreign Addr:port     State       Slot  Cpu PCB

 0.0.0.0:21            0.0.0.0:0             LISTEN      1     0   0xfffffffffff

fff9d

 0.0.0.0:23            0.0.0.0:0             LISTEN      1     0   0xfffffffffff

fff9f

 192.168.2.88:23       192.168.2.79:2197     ESTABLISHED 1     0   0xfffffffffff

fffa3

 192.168.2.88:23       192.168.2.89:2710     ESTABLISHED 1     0   0xfffffffffff

fffa2

 192.168.2.88:23       192.168.2.110:50199   ESTABLISHED 1     0   0xfffffffffff

fff

Configuration files

#

   tcp syn-cookie enable

#

Related documentation

·     H3C S7500X Switch Series Layer 2—LAN Switching Configuration Guide-R759X

·     H3C S7500X Switch Series Layer 2—LAN Switching Command Reference-R759X

·     H3C S7500X Switch Series Layer 3—IP Services Configuration Guide-R759X

·     H3C S7500X Switch Series Layer 3—IP Services Command Reference-R759X

·     H3C S7500X Switch Series Security Configuration Guide-R759X

·     H3C S7500X Switch Series Security Command Reference-R759X