Configuration Prerequisites; Enabling Unauthorized Dhcp Server Detection; Configuring Ip Address Conflict Detection - 3Com MSR 50 Series Configuration Manual

Configuration
Prerequisites
Enabling Unauthorized
DHCP Server Detection
n
Configuring IP Address
Conflict Detection
Before performing this configuration, complete the following configuration on the
DHCP server:
Enable DHCP
■
Configure the DHCP address pool
■
There are unauthorized DHCP servers on networks, which reply DHCP clients with
wrong IP addresses.
With this feature enabled, when receiving a DHCP message with the siaddr field
not being 0 from a client, the DHCP server will record the value of the siaddr field
in the message and the receiving interface. The administrator can use this
information to check out any DHCP unauthorized servers.
To enable unauthorized DHCP server detection, use the following commands:
To do...
Enter system view
Enable unauthorized DHCP
server detection
With the unauthorized DHCP server detection enabled, the device puts a record
once for each DHCP server. The administrator needs to find unauthorized DHCP
servers from the log information.
To avoid IP address conflicts, the DHCP server checks whether the address to be
assigned is in use via sending ping packets.
The DHCP server pings the IP address to be assigned using ICMP. If the server gets
a response within the specified period, the server will ping another IP address;
otherwise, the server will ping the IP addresses once again until the specified
number of ping packets are sent. If still no response, the server will assign the IP
address to the requesting client (The DHCP client probes the IP address by sending
gratuitous ARP packets).
To configure IP address conflict detection, use the following commands:
To do... Use the command...
Enter system view system-view
Specify the number of dhcp server ping
ping packets packets number
Configure the timeout dhcp server ping
value for ping packets timeout milliseconds
Configuring the DHCP Server Security Functions
Use the command...
system-view
dhcp server detect
Remarks
-
Optional
One ping packet by default.
The value "0" indicates that the DHCP
server does not perform any ping collision
detection.
Optional
500 ms by default.
The value "0" indicates that the DHCP
server does not perform any ping collision
detection.
583
Remarks
-
Required
Disabled by default