Network Router User Manual

SmartSwitch Router User Reference Manual 85
Chapter 8: IP Routing Configuration Guide
• BOOTP/DHCP (port 67 and 68)
• DNS (port 37)
• NetBIOS Name Server (port 137)
• NetBIOS Datagram Server (port 138)
• TACACS Server (port 49)
• Time Service (port 37)
To forward UDP broadcast packets received on interface int1 to the host 10.1.4.5 for the six
default UDP services:
To forward UDP broadcast packets received on interface int2 to the host 10.2.48.8 for
packets with the destination port 111 (port mapper):
To forward UDP broadcast packets received on interface int3 to all other interfaces:
Configuring Direct Broadcast
Directed broadcast packets are network or subnet broadcast packets which are sent to a
router to be forwarded as broadcast packets. They can be misused to create Denial Of
Service attacks. The SSR protects against this possibility by not forwarding directed
broadcasts, by default. To enable the forwarding of directed broadcasts, use the ip enable
directed-broadcast command.
You can configure the SSR to forward all directed broadcast traffic from the local subnet to
a specified IP address or all associated IP addresses. This is a more efficient method than
defining only one local interface and remote IP address destination at a time with the ip-
helper command when you are forwarding traffic from more than one interface in the
local subnet to a remote destination IP address.
To enable directed broadcast forwarding on the “int4” network interface:
ssr(config)# ip helper-address interface int1 10.1.4.5
ssr(config)# ip helper-address interface int2 10.2.48.8 111
ssr(config)# ip helper-address interface int3 all-interfaces
ssr(config)# ip enable directed-broadcast interface int4