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Nmap Network Scanning

General Operation

Unlike other ping and packet generation tools, Nping supports multiple target host and port specifications. While this provides great flexibility, it is not obvious how Nping handles situations where there is more than one host and/or more than one port to send probes to. This section explains how Nping behaves in these cases.

When multiple target hosts are specified, Nping rotates among them in round-robin fashion. This gives slow hosts more time to send their responses before another probe is sent to them. Ports are also scheduled using round robin. So, unless only one port is specified, Nping never sends two probes to the same target host and port consecutively.

The loop around targets is the inner loop and the loop around ports is the outer loop. All targets will be sent a probe for a given port before moving on to the next port. Between probes, Nping waits a configurable amount of time called the inter-probe delay, which is controlled by the --delay option. These examples show how it works.

One target, three ports, and two rounds.

# nping --tcp -c 2 1.1.1.1 -p 100-102

Starting Nping ( http://nmap.org/nping )
SENT (0.0210s) TCP 192.168.1.77 > 1.1.1.1:100
SENT (1.0230s) TCP 192.168.1.77 > 1.1.1.1:101
SENT (2.0250s) TCP 192.168.1.77 > 1.1.1.1:102
SENT (3.0280s) TCP 192.168.1.77 > 1.1.1.1:100
SENT (4.0300s) TCP 192.168.1.77 > 1.1.1.1:101
SENT (5.0320s) TCP 192.168.1.77 > 1.1.1.1:102

Three targets, one port, and two rounds.

# nping --tcp -c 2 1.1.1.1 2.2.2.2 3.3.3.3 -p 8080

Starting Nping ( http://nmap.org/nping )
SENT (0.0230s) TCP 192.168.0.21 > 1.1.1.1:8080
SENT (1.0240s) TCP 192.168.0.21 > 2.2.2.2:8080
SENT (2.0260s) TCP 192.168.0.21 > 3.3.3.3:8080
SENT (3.0270s) TCP 192.168.0.21 > 1.1.1.1:8080
SENT (4.0290s) TCP 192.168.0.21 > 2.2.2.2:8080
SENT (5.0310s) TCP 192.168.0.21 > 3.3.3.3:8080

Three hosts, three ports, one round, inter-probe delay of 500 ms.

# nping --tcp -c 1 --delay 500ms 1.1.1.1 2.2.2.2 3.3.3.3 -p 137-139

Starting Nping ( http://nmap.org/nping )
SENT (0.0230s) TCP 192.168.0.21 > 1.1.1.1:137
SENT (0.5250s) TCP 192.168.0.21 > 2.2.2.2:137
SENT (1.0250s) TCP 192.168.0.21 > 3.3.3.3:137
SENT (1.5280s) TCP 192.168.0.21 > 1.1.1.1:138
SENT (2.0280s) TCP 192.168.0.21 > 2.2.2.2:138
SENT (2.5310s) TCP 192.168.0.21 > 3.3.3.3:138
SENT (3.0300s) TCP 192.168.0.21 > 1.1.1.1:139
SENT (3.5330s) TCP 192.168.0.21 > 2.2.2.2:139
SENT (4.0330s) TCP 192.168.0.21 > 3.3.3.3:139
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