yum install nc

# nc -z -v [hostname/IP address] [port number]

# nc -z -v 192.168.10.12 22
Connection to 192.118.20.95 22 port [tcp/ssh] succeeded!

# nc -z -v 192.168.10.12 22
nc: connect to 192.118.20.95 port 22 (tcp) failed: No route to host

# nc -z -v -u [hostname/IP address] [port number]

# nc -z -v -u 192.168.10.12 123
Connection to 192.118.20.95 123 port [udp/ntp] succeeded!