Dear All Can you please do me favor and let me know how can I solve my problem with nmap , as described below : "My CentOS server can ping the network element , but when I try to scan its open ports to see which ones are open at now the nmap cannot distinguish them and returned as they are being filtered : #nmap -sS -p 20-80 172.18.0.1 Can you please let me know how can I modify my nmap command to get through ? Thank you in advance