Ping Sweeps

Ping Sweeps
ping, gping and fping
Having identified potential targets, it is useful to initiate a ping sweep
to see which hosts appear to be alive. This may simply be a series of
ICMP echo-reply exchanges from a standard ping application, or the
ping sweep function of an application, for example:
• fping
• WS Ping Pro
• nmap
Although this will immediately identify readily available hosts, a
negative result will require further examination, possible reasons being:
• The host could truly be down or disconnected from the network.
• The packet has simply been rejected.
• An up-stream filter may have silently dropped the packet.
fping
fping has certain advantages over a batched set of standard pings, as it
is designed to initiate multiple requests, processing the results in
parallel. When combined with its accompanying IP generator, gping,
fping represents a fast and flexible tool for a ping sweep.
Risk Level
Whilst a small number of pings would likely be overlooked, and
therefore carry a Low risk, automated ping sweeps with short time outs
could become visible both to an administrator and to security devices,
and therefore carry a High risk. By increasing the timeout between
checking each host, the risk of discovery would be greatly reduced,
although the scan time would obviously increase.