Port Filtering; Figure 27 Dhcp Relay - WaveRider LMS4000 User Manual

The gateway router can provide DHCP server functionality, or you can implement a dedicated
DHCP server, as shown in
Internet

3.6.2 Port Filtering

The CCU and EUM both support TCP and UDP port filtering. The IP protocol suite is made up
of many subcomponents consisting of ports and protocols. Up-to-date listings of TCP and
UDP ports can be obtained off the Web. Some of these ports are required for normal LMS4000
operation, but most are not. The system operator can configure the CCU and EUM to filter
packets on specific TCP or UDP ports to improve network performance, security, or privacy.
For example, to prevent end-users from having visibility of, and access to, other end-users
through Windows Network Neighborhood, filter the following ports at the CCU for both UDP
and TCP packets:
• Port 137
• Port 138
• Port 139
• Port 1512
APCD-LM043-4.0
Figure 27.
NMS Station
Router Switch
DHCP DHCP
Request Response
(UDP) (UDP)
(with DHCP Relay enabled)
Figure 27
NETBIOS Name Service
NETBIOS Datagram Service
NETBIOS Session Service
Microsoft's Windows Internet Name Service
CAUTION: The EUM is delivered with port filtering enabled.
CAUTION: Do not enable filters to block Telnet (port 23), FTP
(ports 20 and 21), or SNMP (ports 161 and 162); otherwise, you
will not be able to manage your network.
DHCP Server
EUM3000
Antenna
DHCP
Request
DHCP
Response
(layer-2
messages)
CCU3000
DHCP Relay
3 Detailed Description
End-user Computer
(with DHCP enabled)
49