Chapter 15: Denial of Service Defenses
182
Section II: Advanced Operations
Land Attack
In this attack, an attacker sends a bogus IP packet where the source and
destination IP addresses are the same. This leaves the victim thinking that
it is sending a message to itself.
The most direct approach for defending against this form of attack is for
the AT-S63 Management Software to check the source and destination IP
addresses in the IP packets, searching for and discarding those with
identical source and destination addresses. However, this would require
too much processing by the switch’s CPU and would adversely impact
switch performance.
Instead, the switch examines the IP packets that are entering and leaving
your network. IP packets that are generated within your network and
contain a local IP address as the destination address are not allowed to
leave the network, and IP packets that are generated outside the network
but contain a local IP address as the source address are not allowed into
the network.
In order for this defense mechanism to work, you need to specify an uplink
port. This is the port on the switch that is connected to a device, such as a
DSL router, that leads outside your network. You can specify only one
uplink port.
Note
You should not use this defense mechanism on a switch that is not
connected to a device that leads outside your network.
You also need to enter the IP address of one of your network devices as
well as a mask which the switch uses to differentiate between the network
portion and node portion of the address. The switch uses the IP address
and mask to determine which IP addresses are local to your network and
which are from outside you network.
The following is a overview of how the process works. This example
assumes that you have activated the feature on port 4, which is connected
to a device local to your network, and that you specified port 1 as the
uplink port, which is connected to the device that leads outside your
network. The steps below review what happens when an ingress IP
packet from the local device arrives on port 4:
1. When port 4 receives an ingress IP packet with a destination MAC
address learned on uplink port 1, it examines the packet’s source IP
address.
Содержание AT-S63
Страница 14: ...Figures 14 ...
Страница 18: ...Tables 18 ...
Страница 28: ...28 Section I Basic Operations ...
Страница 58: ...Chapter 1 Overview 58 ...
Страница 76: ...Chapter 2 AT 9400Ts Stacks 76 Section I Basic Operations ...
Страница 96: ...Chapter 5 MAC Address Table 96 Section I Basic Operations ...
Страница 114: ...Chapter 8 Port Mirror 114 Section I Basic Operations ...
Страница 116: ...116 Section II Advanced Operations ...
Страница 146: ...Chapter 12 Access Control Lists 146 Section II Advanced Operations ...
Страница 176: ...Chapter 14 Quality of Service 176 Section II Advanced Operations ...
Страница 196: ...196 Section III Snooping Protocols ...
Страница 204: ...Chapter 18 Multicast Listener Discovery Snooping 204 Section III Snooping Protocols ...
Страница 216: ...Chapter 20 Ethernet Protection Switching Ring Snooping 216 Section III Snooping Protocols ...
Страница 218: ...218 Section IV SNMPv3 ...
Страница 234: ...234 Section V Spanning Tree Protocols ...
Страница 268: ...268 Section VI Virtual LANs ...
Страница 306: ...Chapter 27 Protected Ports VLANs 306 Section VI Virtual LANs ...
Страница 320: ...320 Section VII Internet Protocol Routing ...
Страница 360: ...Chapter 30 BOOTP Relay Agent 360 Section VII Routing ...
Страница 370: ...Chapter 31 Virtual Router Redundancy Protocol 370 Section VII Routing ...
Страница 372: ...372 Section VIII Port Security ...
Страница 402: ...Chapter 33 802 1x Port based Network Access Control 402 Section VIII Port Security ...
Страница 404: ...404 Section IX Management Security ...
Страница 436: ...Chapter 36 PKI Certificates and SSL 436 Section IX Management Security ...
Страница 454: ...Chapter 38 TACACS and RADIUS Protocols 454 Section IX Management Security ...
Страница 462: ...Chapter 39 Management Access Control List 462 Section IX Management Security ...
Страница 504: ...Appendix B SNMPv3 Configuration Examples 504 Security Model Security Level Storage Type SNMPv3 Parameters Continued ...
Страница 532: ...Appendix D MIB Objects 532 ...