Planet Networking & Communication WGSW-50040, Configuration Manual, Page: 148 / 267

19-5
debug ip dhcp snooping packet
debug ip dhcp snooping event
debug ip dhcp snooping update
debug ip dhcp snooping binding
Please refer to the chapter on system
troubleshooting.
19.3 DHCP Snooping Typical Application
Figure 19-1 Sketch Map of TRUNK
As showed in the above chart, Mac-AA device is the normal user, connected to the non-trusted port 1/1 of the
switch. It operates via DHCP Client, IP 1.1.1.5; DHCP Server and GateWay are connected to the trusted ports
1/11 and 1/12 of the switch; the malicious user Mac-BB is connected to the non-trusted port 1/10, trying to
fake a DHCP Server
（
by sending DHCPACK
）
. Setting DHCP Snooping on the switch will effectively detect
and block this kind of network attack.
Configuration sequence is:
switch#
switch#config
switch(config)#ip dhcp snooping enable
switch(config)#interface ethernet 1/11
switch(Config-If-Ethernet1/11)#ip dhcp snooping trust
switch(Config-If-Ethernet1/11)#exit
switch(config)#interface ethernet 1/12
switch(Config-If-Ethernet1/12)#ip dhcp snooping trust
switch(Config-If-Ethernet1/12)#exit
switch(config)#interface ethernet 1/1-10
switch(Config-Port-Range)#ip dhcp snooping action shutdown
switch(Config-Port-Range)#