When you select a UDP port, select an available 16-bit integer from the range that follows:
Use available ports in the private range 49152 to 65535
To check which ports are defined as defaults for a node, examine the file /etc/services. You should also use the netstat command to list the UDP ports currently in use. For example:
# netstat -au | more Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State udp 0 0 *:32768 *:* udp 0 0 *:956 *:* udp 0 0 *:tftp *:* udp 0 0 *:sunrpc *:* udp 0 0 *:ipp *:*
Look in the UDP section of the output; the UDP ports that are listed under Local Address are already in use. If a port is listed in the /etc/services file, its associated name is displayed rather than the port number in the output.