Dhcp-Server Detect - 3Com 5500-EI PWR Reference Manual

To improve security and avoid malicious attack to the unused SOCKETs, S5500-EI Ethernet switches
provide the following functions:
UDP 67 and UDP 68 ports used by DHCP are enabled only when DHCP is enabled.
UDP 67 and UDP 68 ports are disabled when DHCP is disabled.
The corresponding implementation is as follows.
When a VLAN interface is mapped to a DHCP server group with the dhcp-server command, the
DHCP relay agent is enabled. At the same time, UDP 67 and UDP 68 ports used by DHCP are
enabled.
When the mapping between a VLAN interface and a DHCP server group is removed with the undo
dhcp-server command, DHCP services are disabled. At the same time, UDP 67 and UDP 68
ports used by DHCP are disabled.
Examples
# Enter system view.
<Sysname> system-view
System View: return to User View with Ctrl+Z.
# Enter VLAN-interface 1 view.
[Sysname] interface vlan-interface 1
# Specify that VLAN-interface 1 corresponds to DHCP server group 1.
[Sysname-Vlan-interface1] dhcp-server 1

dhcp-server detect

Syntax
dhcp-server detect
undo dhcp-server detect
View
System view
Parameters
None
Description
Use the dhcp-server detect command to enable the switch serving as a DHCP relay agent to detect
unauthorized DHCP servers.
Use the undo dhcp-server detect command to disable the unauthorized DHCP server detection
function.
By default, the unauthorized DHCP server detection function is disabled
Related commands: dhcp server, display dhcp-server.
2-6