= nmap - Network exploration tool and security scanner =

It might be installed as default. If not: apt-get install nmap

nmap -P0 -sT -F -o -A ip.address.here

// -P0 = do not try to ping ipaddress. Some firewalls block ICMP // -sT = TCP scan // -F = Fast scan. Only scan specified ports via default nmap // -A = additional info // -o = clean output (not needed)

So telnet will not check to see if a UDP port is open on a host. You'll need nmap for this.

nmap -p udpport -sU ipaddress #You may have to try the above a few times to check and see

Ref: http://techgurulive.com/2008/09/16/how-to-test-udp-connectivity/