The linux nmap command can be used to test UDP connectivity to a specific UDP port or range of ports. Please refer to the examples below for UDP port connectivity testing from linux servers.
Example 1
nmap UDP port test;
nmap -sU -p <port_number(s)> <IP_address or host_name>Example 2
nmap UDP port test on UDP port 53 (DNS);
nmap -sU -p 53 ns1.testdnsserverbbb123.com