When a privileged user tries to scan targets on a local Ethernet network, ARP requests are used unless -send-ip was specified. When executed by an unprivileged user, only SYN packets are sent (using a connect call) to ports 80 and 443 on the target.

The default host discovery done with -sn consists of an ICMP echo request, TCP SYN to port 443, TCP ACK to port 80, and an ICMP timestamp request by default. Often called a ping sweep, and is more reliable than pinging the broadcast address because many hosts do not reply to broadcast queries. It can easily be used to count available machines on a network or monitor server availability. Systems administrators often find this option valuable as well. Knowing how many hosts are up is more valuable to attackers than the list provided by a list scan of every single IP address and host name. It allows light reconnaissance of a target network without attracting much attention. This is by default one step more intrusive than the list scan, and can often be used for the same purposes. This is often known as a “ping scan”, but you can also request that traceroute and NSE host scripts be run. This option tells Nmap not to do a port scan after host discovery, and only print out the available hosts that responded to the scan. Here is a little quote from the man page, nmap(1): -sn (No port scan) Network ID is 192.168.3.0, just substitute the last number by 0. Here at point 2, I have the wlan0 device. Inet6 fe80::c685:8ff:fe94:ee9a/64 scope link valid_lft forever preferred_lft forever Inet6 ::1/128 scope host valid_lft forever preferred_lft foreverĢ: wlan0: mtu 1500 qdisc mq state UP qlen 1000

Please substitute your network identifier and subnet mask.ġ: lo: mtu 65536 qdisc noqueue state UNKNOWN

On my network mac address 446ab79714d5