Difference between revisions of "DHCP spoof attack"
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| − | A DHCP Spoof attack is a illegal DHCP server setup in a LAN environment which configures the clients with wrong IP information. The illegal DHCP server can configure the clients with it self as the default gateway, in which case all non-local traffic will be sent to the illegal DHCP server where the intruder can inspect or alter the packets before they are sent on to the real gateway. this is known as a ''man in the middle'' attack | + | A DHCP Spoof attack is a illegal DHCP server setup in a LAN environment which configures the clients with wrong IP information. The illegal DHCP server can configure the clients with it self as the default gateway, in which case all non-local traffic will be sent to the illegal DHCP server where the intruder can inspect or alter the packets before they are sent on to the real gateway. this is known as a ''man in the middle'' attack. |
| + | = Protecting against DHCP spoof attack = | ||
| + | On the ''access'' switches you can protect against spoofing | ||
| + | <source lang="cli"> | ||
| + | ip dhcp spoofing | ||
| + | interface GigabitEthernet0/1 | ||
| + | description Trunk to Distribution layer and DHCP server | ||
| + | ip dhcp snooping trust | ||
| + | </source> | ||
| + | = Show command = | ||
| + | <source lang="cli"> | ||
| + | Switch# <input>show ip dhcp snooping</input> | ||
| + | Switch DHCP snooping is enabled | ||
| + | DHCP Snooping is configured on the following VLANs: | ||
| + | 10 30-40 100 200-220 | ||
| + | Insertion of option 82 information is enabled | ||
| + | Interface Trusted Rate limit (pps) | ||
| + | --------- ------- ---------------- | ||
| + | FastEthernet0/1 no 20 | ||
| + | FastEthernet0/2 no 20 | ||
| + | GigabitEthernet0/1 yes none | ||
| + | </source> | ||
| + | *See example [[Netband Project - DHCP Snooping]] | ||
| + | *See hackipedia [http://www.hakipedia.com/index.php/DHCP_Starvation DHCP_Starvation] | ||
| + | {{Source cli}} | ||
| + | |||
[[Category:Network]][[Category:Security]][[Category:CCNP]][[Category:CCNP3]] | [[Category:Network]][[Category:Security]][[Category:CCNP]][[Category:CCNP3]] | ||
Latest revision as of 18:18, 28 February 2010
A DHCP Spoof attack is a illegal DHCP server setup in a LAN environment which configures the clients with wrong IP information. The illegal DHCP server can configure the clients with it self as the default gateway, in which case all non-local traffic will be sent to the illegal DHCP server where the intruder can inspect or alter the packets before they are sent on to the real gateway. this is known as a man in the middle attack.
Protecting against DHCP spoof attack
On the access switches you can protect against spoofing
ip dhcp spoofing
interface GigabitEthernet0/1
description Trunk to Distribution layer and DHCP server
ip dhcp snooping trustShow command
Switch# <input>show ip dhcp snooping</input>
Switch DHCP snooping is enabled
DHCP Snooping is configured on the following VLANs:
10 30-40 100 200-220
Insertion of option 82 information is enabled
Interface Trusted Rate limit (pps)
--------- ------- ----------------
FastEthernet0/1 no 20
FastEthernet0/2 no 20
GigabitEthernet0/1 yes none- See example Netband Project - DHCP Snooping
- See hackipedia DHCP_Starvation