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PowerConnect B-Series FCX Configuration Guide
53-1002266-01
Using ACLs to filter ARP packets
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Specify the
<port>
variable in the following formats:
•
PowerConnect B-Series FCX stackable switches –
<stack-unit/slotnum/portnum>
Using ACLs to filter ARP packets
You can use ACLs to filter ARP packets. Without this feature, ACLs cannot be used to permit or deny
incoming ARP packets. Although an ARP packet contains an IP address just as an IP packet does,
an ARP packet is not an IP packet; therefore, it is not subject to normal filtering provided by ACLs.
When a Dell PowerConnect device receives an ARP request, the source MAC and IP addresses are
stored in the device ARP table. A new record in the ARP table overwrites existing records that
contain the same IP address. This behavior can cause a condition called "ARP hijacking", when two
hosts with the same IP address try to send an ARP request to the device.
Normally ARP hijacking is not a problem because IP assignments are done dynamically; however, in
some cases, ARP hijacking can occur, such as when a configuration allows a router interface to
share the IP address of another router interface. Since multiple VLANs and the router interfaces
that are associated with each of the VLANs share the same IP segment, it is possible for two hosts
in two different VLANs to fight for the same IP address in that segment. ARP filtering using ACLs
protects an IP host record in the ARP table from being overwritten by a hijacking host. Using ACLs to
filter ARP requests checks the source IP address in the received ARP packet. Only packets with the
permitted IP address will be allowed to be to be written in the ARP table; others are dropped.
Configuration considerations
•
This feature is available on devices running Layer 3 code. This filtering occurs on the
management processor.
•
The feature is available on physical interfaces and virtual routing interfaces. It is supported on
the following physical interface types Ethernet and trunks.
•
ACLs used to filter ARP packets on a virtual routing interface can be inherited from a previous
interface if the virtual routing interface is defined as a follower virtual routing interface.
Configuring ACLs for ARP filtering
To implement the ACL ARP filtering feature, enter commands such as the following.
PowerConnect(config)# access-list 101 permit ip host 192.168.2.2 any
PowerConnect(config)# access-list 102 permit ip host 192.168.2.3 any
PowerConnect(config)# access-list 103 permit ip host 192.168.2.4 any
PowerConnect(config)# vlan 2
PowerConnect(config-vlan-2)# tag ethe 1/1 to 1/2
PowerConnect(config-vlan-2)# router-interface ve 2
PowerConnect(config-vlan-2)# vlan 3
PowerConnect(config-vlan-3)# tag ethe 1/1 to 1/2
PowerConnect(config-vlan-3)#router-int ve 3
PowerConnect(config-vlan-3)# vlan 4
PowerConnect(config-vlan-4)# tag ethe 1/1 to 1/2
PowerConnect(config-vlan-4)# router-int ve 4
PowerConnect(config-vlan-4)# interface ve 2
PowerConnect(config-ve-2)# ip access-group 101 in
PowerConnect(config-ve-2)# ip address 192.168.2.1/24
PowerConnect(config-ve-2)# ip use-ACL-on-arp 103
Содержание PowerConnect B-FCXs
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Страница 228: ...186 PowerConnect B Series FCX Configuration Guide 53 1002266 01 PowerConnect B Series FCX hitless stacking 5 ...
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Страница 248: ...206 PowerConnect B Series FCX Configuration Guide 53 1002266 01 IPv6 management commands 7 ...
Страница 346: ...304 PowerConnect B Series FCX Configuration Guide 53 1002266 01 802 1s Multiple Spanning Tree Protocol 8 ...
Страница 374: ...332 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Jumbo frame support 9 ...
Страница 424: ...382 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Virtual Switch Redundancy Protocol VSRP 10 ...
Страница 568: ...526 PowerConnect B Series FCX Configuration Guide 53 1002266 01 CLI examples 14 ...
Страница 588: ...546 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Sample application 15 ...
Страница 674: ...632 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Enabling or disabling layer 2 switching 19 ...
Страница 684: ...642 PowerConnect B Series FCX Configuration Guide 53 1002266 01 VLAN based mirroring 20 ...
Страница 724: ...682 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Reading CDP packets 23 ...
Страница 768: ...726 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Clearing cached LLDP neighbor information 24 ...
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Страница 948: ...906 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Configuring MLD snooping 27 ...
Страница 962: ...920 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Displaying CPU utilization statistics 28 ...
Страница 1022: ...980 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Displaying OSPF information 29 ...
Страница 1142: ...1100 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Clearing diagnostic buffers 30 ...
Страница 1258: ...1216 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Using Secure copy with SSH2 33 ...
Страница 1314: ...1272 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Displaying port security information 35 ...
Страница 1348: ...1306 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Example configurations 36 ...
Страница 1406: ...1364 PowerConnect B Series FCX Configuration Guide 53 1002266 01 IP source guard 39 ...
Страница 1422: ...1380 PowerConnect B Series FCX Configuration Guide 53 1002266 01 SNMP v3 Configuration examples 40 ...