ICMP Echo Ping The -PE option performs an ICMP (Internet Control Message Protocol) echo ping on the specified system. Usage syntax: nmap -PE [target] # nmap -PE 192.168.1.254 Starting Nmap 5.00 ( http://nmap.org ) at 2009-08-16 13:26 CDT Interesting ports on home (192.168.1.254): Not shown: 998 closed ports PORT STATE SERVICE 80/tcp open 443/tcp open http https MAC Address: 00:25:3C:5F:5A:89 (2Wire) Nmap done: 1 IP address (1 host up) scanned in 1.89 seconds Performing an ICMP echo ping The -PE option sends a standard ICMP ping to the target to see if it replies. This type of discovery works best on local networks where ICMP packets can be transmitted with few restrictions. Many internet hosts, however, are configured not respond to ICMP packets for security reasons. Note The -PE option is automatically implied if no other ping options are specified.