Checking port available on a remote machine using nc command instead of telnet. Same command can be used to check on a remote server as well, change the 127.0.0.1 with IP address of the server.
Single Port Check
nc -zv 127.0.0.1 80
Range of ports:
nc -zv 127.0.0.1 20-30
Output :
root@server ~]# nc -zv 127.0.0.1 443
Connection to 127.0.0.1 443 port [tcp/https] succeeded!
[root@server ~]# nc -zv 127.0.0.1 443-445
Connection to 127.0.0.1 443 port [tcp/https] succeeded!
Connection to 127.0.0.1 444 port [tcp/snpp] succeeded!
nc: connect to 127.0.0.1 port 445 (tcp) failed: Connection refused
[root@server ~]#